1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2b20a3503SChristoph Lameter /* 314e0f9bcSHugh Dickins * Memory Migration functionality - linux/mm/migrate.c 4b20a3503SChristoph Lameter * 5b20a3503SChristoph Lameter * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter 6b20a3503SChristoph Lameter * 7b20a3503SChristoph Lameter * Page migration was first developed in the context of the memory hotplug 8b20a3503SChristoph Lameter * project. The main authors of the migration code are: 9b20a3503SChristoph Lameter * 10b20a3503SChristoph Lameter * IWAMOTO Toshihiro <iwamoto@valinux.co.jp> 11b20a3503SChristoph Lameter * Hirokazu Takahashi <taka@valinux.co.jp> 12b20a3503SChristoph Lameter * Dave Hansen <haveblue@us.ibm.com> 13cde53535SChristoph Lameter * Christoph Lameter 14b20a3503SChristoph Lameter */ 15b20a3503SChristoph Lameter 16b20a3503SChristoph Lameter #include <linux/migrate.h> 17b95f1b31SPaul Gortmaker #include <linux/export.h> 18b20a3503SChristoph Lameter #include <linux/swap.h> 190697212aSChristoph Lameter #include <linux/swapops.h> 20b20a3503SChristoph Lameter #include <linux/pagemap.h> 21e23ca00bSChristoph Lameter #include <linux/buffer_head.h> 22b20a3503SChristoph Lameter #include <linux/mm_inline.h> 23b488893aSPavel Emelyanov #include <linux/nsproxy.h> 24b20a3503SChristoph Lameter #include <linux/pagevec.h> 25e9995ef9SHugh Dickins #include <linux/ksm.h> 26b20a3503SChristoph Lameter #include <linux/rmap.h> 27b20a3503SChristoph Lameter #include <linux/topology.h> 28b20a3503SChristoph Lameter #include <linux/cpu.h> 29b20a3503SChristoph Lameter #include <linux/cpuset.h> 3004e62a29SChristoph Lameter #include <linux/writeback.h> 31742755a1SChristoph Lameter #include <linux/mempolicy.h> 32742755a1SChristoph Lameter #include <linux/vmalloc.h> 3386c3a764SDavid Quigley #include <linux/security.h> 3442cb14b1SHugh Dickins #include <linux/backing-dev.h> 35bda807d4SMinchan Kim #include <linux/compaction.h> 364f5ca265SAdrian Bunk #include <linux/syscalls.h> 377addf443SDominik Brodowski #include <linux/compat.h> 38290408d4SNaoya Horiguchi #include <linux/hugetlb.h> 398e6ac7faSAneesh Kumar K.V #include <linux/hugetlb_cgroup.h> 405a0e3ad6STejun Heo #include <linux/gfp.h> 41a520110eSChristoph Hellwig #include <linux/pagewalk.h> 42df6ad698SJérôme Glisse #include <linux/pfn_t.h> 43a5430ddaSJérôme Glisse #include <linux/memremap.h> 448315ada7SJérôme Glisse #include <linux/userfaultfd_k.h> 45bf6bddf1SRafael Aquini #include <linux/balloon_compaction.h> 46f714f4f2SMel Gorman #include <linux/mmu_notifier.h> 4733c3fc71SVladimir Davydov #include <linux/page_idle.h> 48d435edcaSVlastimil Babka #include <linux/page_owner.h> 496e84f315SIngo Molnar #include <linux/sched/mm.h> 50197e7e52SLinus Torvalds #include <linux/ptrace.h> 5134290e2cSRalph Campbell #include <linux/oom.h> 52884a6e5dSDave Hansen #include <linux/memory.h> 53b20a3503SChristoph Lameter 540d1836c3SMichal Nazarewicz #include <asm/tlbflush.h> 550d1836c3SMichal Nazarewicz 567b2a2d4aSMel Gorman #define CREATE_TRACE_POINTS 577b2a2d4aSMel Gorman #include <trace/events/migrate.h> 587b2a2d4aSMel Gorman 59b20a3503SChristoph Lameter #include "internal.h" 60b20a3503SChristoph Lameter 619e5bcd61SYisheng Xie int isolate_movable_page(struct page *page, isolate_mode_t mode) 62bda807d4SMinchan Kim { 63bda807d4SMinchan Kim struct address_space *mapping; 64bda807d4SMinchan Kim 65bda807d4SMinchan Kim /* 66bda807d4SMinchan Kim * Avoid burning cycles with pages that are yet under __free_pages(), 67bda807d4SMinchan Kim * or just got freed under us. 68bda807d4SMinchan Kim * 69bda807d4SMinchan Kim * In case we 'win' a race for a movable page being freed under us and 70bda807d4SMinchan Kim * raise its refcount preventing __free_pages() from doing its job 71bda807d4SMinchan Kim * the put_page() at the end of this block will take care of 72bda807d4SMinchan Kim * release this page, thus avoiding a nasty leakage. 73bda807d4SMinchan Kim */ 74bda807d4SMinchan Kim if (unlikely(!get_page_unless_zero(page))) 75bda807d4SMinchan Kim goto out; 76bda807d4SMinchan Kim 77bda807d4SMinchan Kim /* 78bda807d4SMinchan Kim * Check PageMovable before holding a PG_lock because page's owner 79bda807d4SMinchan Kim * assumes anybody doesn't touch PG_lock of newly allocated page 808bb4e7a2SWei Yang * so unconditionally grabbing the lock ruins page's owner side. 81bda807d4SMinchan Kim */ 82bda807d4SMinchan Kim if (unlikely(!__PageMovable(page))) 83bda807d4SMinchan Kim goto out_putpage; 84bda807d4SMinchan Kim /* 85bda807d4SMinchan Kim * As movable pages are not isolated from LRU lists, concurrent 86bda807d4SMinchan Kim * compaction threads can race against page migration functions 87bda807d4SMinchan Kim * as well as race against the releasing a page. 88bda807d4SMinchan Kim * 89bda807d4SMinchan Kim * In order to avoid having an already isolated movable page 90bda807d4SMinchan Kim * being (wrongly) re-isolated while it is under migration, 91bda807d4SMinchan Kim * or to avoid attempting to isolate pages being released, 92bda807d4SMinchan Kim * lets be sure we have the page lock 93bda807d4SMinchan Kim * before proceeding with the movable page isolation steps. 94bda807d4SMinchan Kim */ 95bda807d4SMinchan Kim if (unlikely(!trylock_page(page))) 96bda807d4SMinchan Kim goto out_putpage; 97bda807d4SMinchan Kim 98bda807d4SMinchan Kim if (!PageMovable(page) || PageIsolated(page)) 99bda807d4SMinchan Kim goto out_no_isolated; 100bda807d4SMinchan Kim 101bda807d4SMinchan Kim mapping = page_mapping(page); 102bda807d4SMinchan Kim VM_BUG_ON_PAGE(!mapping, page); 103bda807d4SMinchan Kim 104bda807d4SMinchan Kim if (!mapping->a_ops->isolate_page(page, mode)) 105bda807d4SMinchan Kim goto out_no_isolated; 106bda807d4SMinchan Kim 107bda807d4SMinchan Kim /* Driver shouldn't use PG_isolated bit of page->flags */ 108bda807d4SMinchan Kim WARN_ON_ONCE(PageIsolated(page)); 109bda807d4SMinchan Kim __SetPageIsolated(page); 110bda807d4SMinchan Kim unlock_page(page); 111bda807d4SMinchan Kim 1129e5bcd61SYisheng Xie return 0; 113bda807d4SMinchan Kim 114bda807d4SMinchan Kim out_no_isolated: 115bda807d4SMinchan Kim unlock_page(page); 116bda807d4SMinchan Kim out_putpage: 117bda807d4SMinchan Kim put_page(page); 118bda807d4SMinchan Kim out: 1199e5bcd61SYisheng Xie return -EBUSY; 120bda807d4SMinchan Kim } 121bda807d4SMinchan Kim 122606a6f71SMiaohe Lin static void putback_movable_page(struct page *page) 123bda807d4SMinchan Kim { 124bda807d4SMinchan Kim struct address_space *mapping; 125bda807d4SMinchan Kim 126bda807d4SMinchan Kim mapping = page_mapping(page); 127bda807d4SMinchan Kim mapping->a_ops->putback_page(page); 128bda807d4SMinchan Kim __ClearPageIsolated(page); 129bda807d4SMinchan Kim } 130bda807d4SMinchan Kim 131b20a3503SChristoph Lameter /* 1325733c7d1SRafael Aquini * Put previously isolated pages back onto the appropriate lists 1335733c7d1SRafael Aquini * from where they were once taken off for compaction/migration. 1345733c7d1SRafael Aquini * 13559c82b70SJoonsoo Kim * This function shall be used whenever the isolated pageset has been 13659c82b70SJoonsoo Kim * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range() 13759c82b70SJoonsoo Kim * and isolate_huge_page(). 1385733c7d1SRafael Aquini */ 1395733c7d1SRafael Aquini void putback_movable_pages(struct list_head *l) 1405733c7d1SRafael Aquini { 1415733c7d1SRafael Aquini struct page *page; 1425733c7d1SRafael Aquini struct page *page2; 1435733c7d1SRafael Aquini 1445733c7d1SRafael Aquini list_for_each_entry_safe(page, page2, l, lru) { 14531caf665SNaoya Horiguchi if (unlikely(PageHuge(page))) { 14631caf665SNaoya Horiguchi putback_active_hugepage(page); 14731caf665SNaoya Horiguchi continue; 14831caf665SNaoya Horiguchi } 1495733c7d1SRafael Aquini list_del(&page->lru); 150bda807d4SMinchan Kim /* 151bda807d4SMinchan Kim * We isolated non-lru movable page so here we can use 152bda807d4SMinchan Kim * __PageMovable because LRU page's mapping cannot have 153bda807d4SMinchan Kim * PAGE_MAPPING_MOVABLE. 154bda807d4SMinchan Kim */ 155b1123ea6SMinchan Kim if (unlikely(__PageMovable(page))) { 156bda807d4SMinchan Kim VM_BUG_ON_PAGE(!PageIsolated(page), page); 157bda807d4SMinchan Kim lock_page(page); 158bda807d4SMinchan Kim if (PageMovable(page)) 159bda807d4SMinchan Kim putback_movable_page(page); 160bf6bddf1SRafael Aquini else 161bda807d4SMinchan Kim __ClearPageIsolated(page); 162bda807d4SMinchan Kim unlock_page(page); 163bda807d4SMinchan Kim put_page(page); 164bda807d4SMinchan Kim } else { 165e8db67ebSNaoya Horiguchi mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + 1666c357848SMatthew Wilcox (Oracle) page_is_file_lru(page), -thp_nr_pages(page)); 167fc280fe8SRabin Vincent putback_lru_page(page); 168b20a3503SChristoph Lameter } 169b20a3503SChristoph Lameter } 170bda807d4SMinchan Kim } 171b20a3503SChristoph Lameter 1720697212aSChristoph Lameter /* 1730697212aSChristoph Lameter * Restore a potential migration pte to a working pte entry 1740697212aSChristoph Lameter */ 175e4b82222SMinchan Kim static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, 176e9995ef9SHugh Dickins unsigned long addr, void *old) 1770697212aSChristoph Lameter { 1783fe87967SKirill A. Shutemov struct page_vma_mapped_walk pvmw = { 1793fe87967SKirill A. Shutemov .page = old, 1803fe87967SKirill A. Shutemov .vma = vma, 1813fe87967SKirill A. Shutemov .address = addr, 1823fe87967SKirill A. Shutemov .flags = PVMW_SYNC | PVMW_MIGRATION, 1833fe87967SKirill A. Shutemov }; 1843fe87967SKirill A. Shutemov struct page *new; 1853fe87967SKirill A. Shutemov pte_t pte; 1860697212aSChristoph Lameter swp_entry_t entry; 1870697212aSChristoph Lameter 1883fe87967SKirill A. Shutemov VM_BUG_ON_PAGE(PageTail(page), page); 1893fe87967SKirill A. Shutemov while (page_vma_mapped_walk(&pvmw)) { 1904b0ece6fSNaoya Horiguchi if (PageKsm(page)) 1914b0ece6fSNaoya Horiguchi new = page; 1924b0ece6fSNaoya Horiguchi else 1933fe87967SKirill A. Shutemov new = page - pvmw.page->index + 1943fe87967SKirill A. Shutemov linear_page_index(vma, pvmw.address); 1950697212aSChristoph Lameter 196616b8371SZi Yan #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 197616b8371SZi Yan /* PMD-mapped THP migration entry */ 198616b8371SZi Yan if (!pvmw.pte) { 199616b8371SZi Yan VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page); 200616b8371SZi Yan remove_migration_pmd(&pvmw, new); 201616b8371SZi Yan continue; 202616b8371SZi Yan } 203616b8371SZi Yan #endif 204616b8371SZi Yan 2050697212aSChristoph Lameter get_page(new); 2066d2329f8SAndrea Arcangeli pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot))); 2073fe87967SKirill A. Shutemov if (pte_swp_soft_dirty(*pvmw.pte)) 208c3d16e16SCyrill Gorcunov pte = pte_mksoft_dirty(pte); 209d3cb8bf6SMel Gorman 2103fe87967SKirill A. Shutemov /* 2113fe87967SKirill A. Shutemov * Recheck VMA as permissions can change since migration started 2123fe87967SKirill A. Shutemov */ 2133fe87967SKirill A. Shutemov entry = pte_to_swp_entry(*pvmw.pte); 2144dd845b5SAlistair Popple if (is_writable_migration_entry(entry)) 215d3cb8bf6SMel Gorman pte = maybe_mkwrite(pte, vma); 216f45ec5ffSPeter Xu else if (pte_swp_uffd_wp(*pvmw.pte)) 217f45ec5ffSPeter Xu pte = pte_mkuffd_wp(pte); 218d3cb8bf6SMel Gorman 2196128763fSRalph Campbell if (unlikely(is_device_private_page(new))) { 2204dd845b5SAlistair Popple if (pte_write(pte)) 2214dd845b5SAlistair Popple entry = make_writable_device_private_entry( 2224dd845b5SAlistair Popple page_to_pfn(new)); 2234dd845b5SAlistair Popple else 2244dd845b5SAlistair Popple entry = make_readable_device_private_entry( 2254dd845b5SAlistair Popple page_to_pfn(new)); 226a5430ddaSJérôme Glisse pte = swp_entry_to_pte(entry); 2273d321bf8SRalph Campbell if (pte_swp_soft_dirty(*pvmw.pte)) 2283d321bf8SRalph Campbell pte = pte_swp_mksoft_dirty(pte); 229f45ec5ffSPeter Xu if (pte_swp_uffd_wp(*pvmw.pte)) 230ebdf8321SAlistair Popple pte = pte_swp_mkuffd_wp(pte); 231df6ad698SJérôme Glisse } 232a5430ddaSJérôme Glisse 2333ef8fd7fSAndi Kleen #ifdef CONFIG_HUGETLB_PAGE 234be7517d6STony Lu if (PageHuge(new)) { 23579c1c594SChristophe Leroy unsigned int shift = huge_page_shift(hstate_vma(vma)); 23679c1c594SChristophe Leroy 237290408d4SNaoya Horiguchi pte = pte_mkhuge(pte); 23879c1c594SChristophe Leroy pte = arch_make_huge_pte(pte, shift, vma->vm_flags); 239383321abSAneesh Kumar K.V set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); 24004e62a29SChristoph Lameter if (PageAnon(new)) 2413fe87967SKirill A. Shutemov hugepage_add_anon_rmap(new, vma, pvmw.address); 242290408d4SNaoya Horiguchi else 24353f9263bSKirill A. Shutemov page_dup_rmap(new, true); 244383321abSAneesh Kumar K.V } else 245383321abSAneesh Kumar K.V #endif 246383321abSAneesh Kumar K.V { 247383321abSAneesh Kumar K.V set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); 248383321abSAneesh Kumar K.V 249383321abSAneesh Kumar K.V if (PageAnon(new)) 2503fe87967SKirill A. Shutemov page_add_anon_rmap(new, vma, pvmw.address, false); 25104e62a29SChristoph Lameter else 252dd78feddSKirill A. Shutemov page_add_file_rmap(new, false); 253383321abSAneesh Kumar K.V } 254e388466dSKirill A. Shutemov if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new)) 25551afb12bSHugh Dickins mlock_vma_page(new); 25651afb12bSHugh Dickins 257e125fe40SKirill A. Shutemov if (PageTransHuge(page) && PageMlocked(page)) 258e125fe40SKirill A. Shutemov clear_page_mlock(page); 259e125fe40SKirill A. Shutemov 26004e62a29SChristoph Lameter /* No need to invalidate - it was non-present before */ 2613fe87967SKirill A. Shutemov update_mmu_cache(vma, pvmw.address, pvmw.pte); 2623fe87967SKirill A. Shutemov } 2633fe87967SKirill A. Shutemov 264e4b82222SMinchan Kim return true; 2650697212aSChristoph Lameter } 2660697212aSChristoph Lameter 2670697212aSChristoph Lameter /* 26804e62a29SChristoph Lameter * Get rid of all migration entries and replace them by 26904e62a29SChristoph Lameter * references to the indicated page. 27004e62a29SChristoph Lameter */ 271e388466dSKirill A. Shutemov void remove_migration_ptes(struct page *old, struct page *new, bool locked) 27204e62a29SChristoph Lameter { 273051ac83aSJoonsoo Kim struct rmap_walk_control rwc = { 274051ac83aSJoonsoo Kim .rmap_one = remove_migration_pte, 275051ac83aSJoonsoo Kim .arg = old, 276051ac83aSJoonsoo Kim }; 277051ac83aSJoonsoo Kim 278e388466dSKirill A. Shutemov if (locked) 279e388466dSKirill A. Shutemov rmap_walk_locked(new, &rwc); 280e388466dSKirill A. Shutemov else 281051ac83aSJoonsoo Kim rmap_walk(new, &rwc); 28204e62a29SChristoph Lameter } 28304e62a29SChristoph Lameter 28404e62a29SChristoph Lameter /* 2850697212aSChristoph Lameter * Something used the pte of a page under migration. We need to 2860697212aSChristoph Lameter * get to the page and wait until migration is finished. 2870697212aSChristoph Lameter * When we return from this function the fault will be retried. 2880697212aSChristoph Lameter */ 289e66f17ffSNaoya Horiguchi void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, 29030dad309SNaoya Horiguchi spinlock_t *ptl) 2910697212aSChristoph Lameter { 29230dad309SNaoya Horiguchi pte_t pte; 2930697212aSChristoph Lameter swp_entry_t entry; 2940697212aSChristoph Lameter struct page *page; 2950697212aSChristoph Lameter 29630dad309SNaoya Horiguchi spin_lock(ptl); 2970697212aSChristoph Lameter pte = *ptep; 2980697212aSChristoph Lameter if (!is_swap_pte(pte)) 2990697212aSChristoph Lameter goto out; 3000697212aSChristoph Lameter 3010697212aSChristoph Lameter entry = pte_to_swp_entry(pte); 3020697212aSChristoph Lameter if (!is_migration_entry(entry)) 3030697212aSChristoph Lameter goto out; 3040697212aSChristoph Lameter 305af5cdaf8SAlistair Popple page = pfn_swap_entry_to_page(entry); 306ffc90cbbSXu Yu page = compound_head(page); 3070697212aSChristoph Lameter 308e286781dSNick Piggin /* 30989eb946aSMatthew Wilcox * Once page cache replacement of page migration started, page_count 3109a1ea439SHugh Dickins * is zero; but we must not call put_and_wait_on_page_locked() without 3119a1ea439SHugh Dickins * a ref. Use get_page_unless_zero(), and just fault again if it fails. 312e286781dSNick Piggin */ 313e286781dSNick Piggin if (!get_page_unless_zero(page)) 314e286781dSNick Piggin goto out; 3150697212aSChristoph Lameter pte_unmap_unlock(ptep, ptl); 31648054625SMatthew Wilcox (Oracle) put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE); 3170697212aSChristoph Lameter return; 3180697212aSChristoph Lameter out: 3190697212aSChristoph Lameter pte_unmap_unlock(ptep, ptl); 3200697212aSChristoph Lameter } 3210697212aSChristoph Lameter 32230dad309SNaoya Horiguchi void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, 32330dad309SNaoya Horiguchi unsigned long address) 32430dad309SNaoya Horiguchi { 32530dad309SNaoya Horiguchi spinlock_t *ptl = pte_lockptr(mm, pmd); 32630dad309SNaoya Horiguchi pte_t *ptep = pte_offset_map(pmd, address); 32730dad309SNaoya Horiguchi __migration_entry_wait(mm, ptep, ptl); 32830dad309SNaoya Horiguchi } 32930dad309SNaoya Horiguchi 330cb900f41SKirill A. Shutemov void migration_entry_wait_huge(struct vm_area_struct *vma, 331cb900f41SKirill A. Shutemov struct mm_struct *mm, pte_t *pte) 33230dad309SNaoya Horiguchi { 333cb900f41SKirill A. Shutemov spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); 33430dad309SNaoya Horiguchi __migration_entry_wait(mm, pte, ptl); 33530dad309SNaoya Horiguchi } 33630dad309SNaoya Horiguchi 337616b8371SZi Yan #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 338616b8371SZi Yan void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd) 339616b8371SZi Yan { 340616b8371SZi Yan spinlock_t *ptl; 341616b8371SZi Yan struct page *page; 342616b8371SZi Yan 343616b8371SZi Yan ptl = pmd_lock(mm, pmd); 344616b8371SZi Yan if (!is_pmd_migration_entry(*pmd)) 345616b8371SZi Yan goto unlock; 346af5cdaf8SAlistair Popple page = pfn_swap_entry_to_page(pmd_to_swp_entry(*pmd)); 347616b8371SZi Yan if (!get_page_unless_zero(page)) 348616b8371SZi Yan goto unlock; 349616b8371SZi Yan spin_unlock(ptl); 35048054625SMatthew Wilcox (Oracle) put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE); 351616b8371SZi Yan return; 352616b8371SZi Yan unlock: 353616b8371SZi Yan spin_unlock(ptl); 354616b8371SZi Yan } 355616b8371SZi Yan #endif 356616b8371SZi Yan 357f900482dSJan Kara static int expected_page_refs(struct address_space *mapping, struct page *page) 3580b3901b3SJan Kara { 3590b3901b3SJan Kara int expected_count = 1; 3600b3901b3SJan Kara 3610b3901b3SJan Kara /* 362f1f4f3abSRalph Campbell * Device private pages have an extra refcount as they are 3630b3901b3SJan Kara * ZONE_DEVICE pages. 3640b3901b3SJan Kara */ 3650b3901b3SJan Kara expected_count += is_device_private_page(page); 366f900482dSJan Kara if (mapping) 3676c357848SMatthew Wilcox (Oracle) expected_count += thp_nr_pages(page) + page_has_private(page); 3680b3901b3SJan Kara 3690b3901b3SJan Kara return expected_count; 3700b3901b3SJan Kara } 3710b3901b3SJan Kara 372b20a3503SChristoph Lameter /* 373c3fcf8a5SChristoph Lameter * Replace the page in the mapping. 3745b5c7120SChristoph Lameter * 3755b5c7120SChristoph Lameter * The number of remaining references must be: 3765b5c7120SChristoph Lameter * 1 for anonymous pages without a mapping 3775b5c7120SChristoph Lameter * 2 for pages with a mapping 378266cf658SDavid Howells * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. 379b20a3503SChristoph Lameter */ 38036bc08ccSGu Zheng int migrate_page_move_mapping(struct address_space *mapping, 38137109694SKeith Busch struct page *newpage, struct page *page, int extra_count) 382b20a3503SChristoph Lameter { 38389eb946aSMatthew Wilcox XA_STATE(xas, &mapping->i_pages, page_index(page)); 38442cb14b1SHugh Dickins struct zone *oldzone, *newzone; 38542cb14b1SHugh Dickins int dirty; 386f900482dSJan Kara int expected_count = expected_page_refs(mapping, page) + extra_count; 3875c447d27SShakeel Butt int nr = thp_nr_pages(page); 3888763cb45SJérôme Glisse 3896c5240aeSChristoph Lameter if (!mapping) { 3900e8c7d0fSChristoph Lameter /* Anonymous page without mapping */ 3918e321fefSBenjamin LaHaise if (page_count(page) != expected_count) 3926c5240aeSChristoph Lameter return -EAGAIN; 393cf4b769aSHugh Dickins 394cf4b769aSHugh Dickins /* No turning back from here */ 395cf4b769aSHugh Dickins newpage->index = page->index; 396cf4b769aSHugh Dickins newpage->mapping = page->mapping; 397cf4b769aSHugh Dickins if (PageSwapBacked(page)) 398fa9949daSHugh Dickins __SetPageSwapBacked(newpage); 399cf4b769aSHugh Dickins 40078bd5209SRafael Aquini return MIGRATEPAGE_SUCCESS; 4016c5240aeSChristoph Lameter } 4026c5240aeSChristoph Lameter 40342cb14b1SHugh Dickins oldzone = page_zone(page); 40442cb14b1SHugh Dickins newzone = page_zone(newpage); 40542cb14b1SHugh Dickins 40689eb946aSMatthew Wilcox xas_lock_irq(&xas); 40789eb946aSMatthew Wilcox if (page_count(page) != expected_count || xas_load(&xas) != page) { 40889eb946aSMatthew Wilcox xas_unlock_irq(&xas); 409e23ca00bSChristoph Lameter return -EAGAIN; 410b20a3503SChristoph Lameter } 411b20a3503SChristoph Lameter 412fe896d18SJoonsoo Kim if (!page_ref_freeze(page, expected_count)) { 41389eb946aSMatthew Wilcox xas_unlock_irq(&xas); 414e286781dSNick Piggin return -EAGAIN; 415e286781dSNick Piggin } 416e286781dSNick Piggin 417b20a3503SChristoph Lameter /* 418cf4b769aSHugh Dickins * Now we know that no one else is looking at the page: 419cf4b769aSHugh Dickins * no turning back from here. 420b20a3503SChristoph Lameter */ 421cf4b769aSHugh Dickins newpage->index = page->index; 422cf4b769aSHugh Dickins newpage->mapping = page->mapping; 4235c447d27SShakeel Butt page_ref_add(newpage, nr); /* add cache reference */ 4246326fec1SNicholas Piggin if (PageSwapBacked(page)) { 4256326fec1SNicholas Piggin __SetPageSwapBacked(newpage); 426b20a3503SChristoph Lameter if (PageSwapCache(page)) { 427b20a3503SChristoph Lameter SetPageSwapCache(newpage); 428b20a3503SChristoph Lameter set_page_private(newpage, page_private(page)); 429b20a3503SChristoph Lameter } 4306326fec1SNicholas Piggin } else { 4316326fec1SNicholas Piggin VM_BUG_ON_PAGE(PageSwapCache(page), page); 4326326fec1SNicholas Piggin } 433b20a3503SChristoph Lameter 43442cb14b1SHugh Dickins /* Move dirty while page refs frozen and newpage not yet exposed */ 43542cb14b1SHugh Dickins dirty = PageDirty(page); 43642cb14b1SHugh Dickins if (dirty) { 43742cb14b1SHugh Dickins ClearPageDirty(page); 43842cb14b1SHugh Dickins SetPageDirty(newpage); 43942cb14b1SHugh Dickins } 44042cb14b1SHugh Dickins 44189eb946aSMatthew Wilcox xas_store(&xas, newpage); 442e71769aeSNaoya Horiguchi if (PageTransHuge(page)) { 443e71769aeSNaoya Horiguchi int i; 444e71769aeSNaoya Horiguchi 4455c447d27SShakeel Butt for (i = 1; i < nr; i++) { 44689eb946aSMatthew Wilcox xas_next(&xas); 4474101196bSMatthew Wilcox (Oracle) xas_store(&xas, newpage); 448e71769aeSNaoya Horiguchi } 449e71769aeSNaoya Horiguchi } 4507cf9c2c7SNick Piggin 4517cf9c2c7SNick Piggin /* 452937a94c9SJacobo Giralt * Drop cache reference from old page by unfreezing 453937a94c9SJacobo Giralt * to one less reference. 4547cf9c2c7SNick Piggin * We know this isn't the last reference. 4557cf9c2c7SNick Piggin */ 4565c447d27SShakeel Butt page_ref_unfreeze(page, expected_count - nr); 4577cf9c2c7SNick Piggin 45889eb946aSMatthew Wilcox xas_unlock(&xas); 45942cb14b1SHugh Dickins /* Leave irq disabled to prevent preemption while updating stats */ 46042cb14b1SHugh Dickins 4610e8c7d0fSChristoph Lameter /* 4620e8c7d0fSChristoph Lameter * If moved to a different zone then also account 4630e8c7d0fSChristoph Lameter * the page for that zone. Other VM counters will be 4640e8c7d0fSChristoph Lameter * taken care of when we establish references to the 4650e8c7d0fSChristoph Lameter * new page and drop references to the old page. 4660e8c7d0fSChristoph Lameter * 4670e8c7d0fSChristoph Lameter * Note that anonymous pages are accounted for 4684b9d0fabSMel Gorman * via NR_FILE_PAGES and NR_ANON_MAPPED if they 4690e8c7d0fSChristoph Lameter * are mapped to swap space. 4700e8c7d0fSChristoph Lameter */ 47142cb14b1SHugh Dickins if (newzone != oldzone) { 4720d1c2072SJohannes Weiner struct lruvec *old_lruvec, *new_lruvec; 4730d1c2072SJohannes Weiner struct mem_cgroup *memcg; 4740d1c2072SJohannes Weiner 4750d1c2072SJohannes Weiner memcg = page_memcg(page); 4760d1c2072SJohannes Weiner old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat); 4770d1c2072SJohannes Weiner new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat); 4780d1c2072SJohannes Weiner 4795c447d27SShakeel Butt __mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr); 4805c447d27SShakeel Butt __mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr); 48142cb14b1SHugh Dickins if (PageSwapBacked(page) && !PageSwapCache(page)) { 4825c447d27SShakeel Butt __mod_lruvec_state(old_lruvec, NR_SHMEM, -nr); 4835c447d27SShakeel Butt __mod_lruvec_state(new_lruvec, NR_SHMEM, nr); 4844b02108aSKOSAKI Motohiro } 485b6038942SShakeel Butt #ifdef CONFIG_SWAP 486b6038942SShakeel Butt if (PageSwapCache(page)) { 487b6038942SShakeel Butt __mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr); 488b6038942SShakeel Butt __mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr); 489b6038942SShakeel Butt } 490b6038942SShakeel Butt #endif 491f56753acSChristoph Hellwig if (dirty && mapping_can_writeback(mapping)) { 4925c447d27SShakeel Butt __mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr); 4935c447d27SShakeel Butt __mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr); 4945c447d27SShakeel Butt __mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr); 4955c447d27SShakeel Butt __mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr); 49642cb14b1SHugh Dickins } 49742cb14b1SHugh Dickins } 49842cb14b1SHugh Dickins local_irq_enable(); 499b20a3503SChristoph Lameter 50078bd5209SRafael Aquini return MIGRATEPAGE_SUCCESS; 501b20a3503SChristoph Lameter } 5021118dce7SRichard Weinberger EXPORT_SYMBOL(migrate_page_move_mapping); 503b20a3503SChristoph Lameter 504b20a3503SChristoph Lameter /* 505290408d4SNaoya Horiguchi * The expected number of remaining references is the same as that 506290408d4SNaoya Horiguchi * of migrate_page_move_mapping(). 507290408d4SNaoya Horiguchi */ 508290408d4SNaoya Horiguchi int migrate_huge_page_move_mapping(struct address_space *mapping, 509290408d4SNaoya Horiguchi struct page *newpage, struct page *page) 510290408d4SNaoya Horiguchi { 51189eb946aSMatthew Wilcox XA_STATE(xas, &mapping->i_pages, page_index(page)); 512290408d4SNaoya Horiguchi int expected_count; 513290408d4SNaoya Horiguchi 51489eb946aSMatthew Wilcox xas_lock_irq(&xas); 515290408d4SNaoya Horiguchi expected_count = 2 + page_has_private(page); 51689eb946aSMatthew Wilcox if (page_count(page) != expected_count || xas_load(&xas) != page) { 51789eb946aSMatthew Wilcox xas_unlock_irq(&xas); 518290408d4SNaoya Horiguchi return -EAGAIN; 519290408d4SNaoya Horiguchi } 520290408d4SNaoya Horiguchi 521fe896d18SJoonsoo Kim if (!page_ref_freeze(page, expected_count)) { 52289eb946aSMatthew Wilcox xas_unlock_irq(&xas); 523290408d4SNaoya Horiguchi return -EAGAIN; 524290408d4SNaoya Horiguchi } 525290408d4SNaoya Horiguchi 526cf4b769aSHugh Dickins newpage->index = page->index; 527cf4b769aSHugh Dickins newpage->mapping = page->mapping; 5286a93ca8fSJohannes Weiner 529290408d4SNaoya Horiguchi get_page(newpage); 530290408d4SNaoya Horiguchi 53189eb946aSMatthew Wilcox xas_store(&xas, newpage); 532290408d4SNaoya Horiguchi 533fe896d18SJoonsoo Kim page_ref_unfreeze(page, expected_count - 1); 534290408d4SNaoya Horiguchi 53589eb946aSMatthew Wilcox xas_unlock_irq(&xas); 5366a93ca8fSJohannes Weiner 53778bd5209SRafael Aquini return MIGRATEPAGE_SUCCESS; 538290408d4SNaoya Horiguchi } 539290408d4SNaoya Horiguchi 540290408d4SNaoya Horiguchi /* 541b20a3503SChristoph Lameter * Copy the page to its new location 542b20a3503SChristoph Lameter */ 5432916ecc0SJérôme Glisse void migrate_page_states(struct page *newpage, struct page *page) 544b20a3503SChristoph Lameter { 5457851a45cSRik van Riel int cpupid; 5467851a45cSRik van Riel 547b20a3503SChristoph Lameter if (PageError(page)) 548b20a3503SChristoph Lameter SetPageError(newpage); 549b20a3503SChristoph Lameter if (PageReferenced(page)) 550b20a3503SChristoph Lameter SetPageReferenced(newpage); 551b20a3503SChristoph Lameter if (PageUptodate(page)) 552b20a3503SChristoph Lameter SetPageUptodate(newpage); 553894bc310SLee Schermerhorn if (TestClearPageActive(page)) { 554309381feSSasha Levin VM_BUG_ON_PAGE(PageUnevictable(page), page); 555b20a3503SChristoph Lameter SetPageActive(newpage); 556418b27efSLee Schermerhorn } else if (TestClearPageUnevictable(page)) 557418b27efSLee Schermerhorn SetPageUnevictable(newpage); 5581899ad18SJohannes Weiner if (PageWorkingset(page)) 5591899ad18SJohannes Weiner SetPageWorkingset(newpage); 560b20a3503SChristoph Lameter if (PageChecked(page)) 561b20a3503SChristoph Lameter SetPageChecked(newpage); 562b20a3503SChristoph Lameter if (PageMappedToDisk(page)) 563b20a3503SChristoph Lameter SetPageMappedToDisk(newpage); 564b20a3503SChristoph Lameter 56542cb14b1SHugh Dickins /* Move dirty on pages not done by migrate_page_move_mapping() */ 56642cb14b1SHugh Dickins if (PageDirty(page)) 567752dc185SHugh Dickins SetPageDirty(newpage); 568b20a3503SChristoph Lameter 56933c3fc71SVladimir Davydov if (page_is_young(page)) 57033c3fc71SVladimir Davydov set_page_young(newpage); 57133c3fc71SVladimir Davydov if (page_is_idle(page)) 57233c3fc71SVladimir Davydov set_page_idle(newpage); 57333c3fc71SVladimir Davydov 5747851a45cSRik van Riel /* 5757851a45cSRik van Riel * Copy NUMA information to the new page, to prevent over-eager 5767851a45cSRik van Riel * future migrations of this same page. 5777851a45cSRik van Riel */ 5787851a45cSRik van Riel cpupid = page_cpupid_xchg_last(page, -1); 5797851a45cSRik van Riel page_cpupid_xchg_last(newpage, cpupid); 5807851a45cSRik van Riel 581e9995ef9SHugh Dickins ksm_migrate_page(newpage, page); 582c8d6553bSHugh Dickins /* 583c8d6553bSHugh Dickins * Please do not reorder this without considering how mm/ksm.c's 584c8d6553bSHugh Dickins * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). 585c8d6553bSHugh Dickins */ 586b3b3a99cSNaoya Horiguchi if (PageSwapCache(page)) 587b20a3503SChristoph Lameter ClearPageSwapCache(page); 588b20a3503SChristoph Lameter ClearPagePrivate(page); 589ad2fa371SMuchun Song 590ad2fa371SMuchun Song /* page->private contains hugetlb specific flags */ 591ad2fa371SMuchun Song if (!PageHuge(page)) 592b20a3503SChristoph Lameter set_page_private(page, 0); 593b20a3503SChristoph Lameter 594b20a3503SChristoph Lameter /* 595b20a3503SChristoph Lameter * If any waiters have accumulated on the new page then 596b20a3503SChristoph Lameter * wake them up. 597b20a3503SChristoph Lameter */ 598b20a3503SChristoph Lameter if (PageWriteback(newpage)) 599b20a3503SChristoph Lameter end_page_writeback(newpage); 600d435edcaSVlastimil Babka 6016aeff241SYang Shi /* 6026aeff241SYang Shi * PG_readahead shares the same bit with PG_reclaim. The above 6036aeff241SYang Shi * end_page_writeback() may clear PG_readahead mistakenly, so set the 6046aeff241SYang Shi * bit after that. 6056aeff241SYang Shi */ 6066aeff241SYang Shi if (PageReadahead(page)) 6076aeff241SYang Shi SetPageReadahead(newpage); 6086aeff241SYang Shi 609d435edcaSVlastimil Babka copy_page_owner(page, newpage); 61074485cf2SJohannes Weiner 611a333e3e7SHugh Dickins if (!PageHuge(page)) 61274485cf2SJohannes Weiner mem_cgroup_migrate(page, newpage); 613b20a3503SChristoph Lameter } 6142916ecc0SJérôme Glisse EXPORT_SYMBOL(migrate_page_states); 6152916ecc0SJérôme Glisse 6162916ecc0SJérôme Glisse void migrate_page_copy(struct page *newpage, struct page *page) 6172916ecc0SJérôme Glisse { 6182916ecc0SJérôme Glisse if (PageHuge(page) || PageTransHuge(page)) 6192916ecc0SJérôme Glisse copy_huge_page(newpage, page); 6202916ecc0SJérôme Glisse else 6212916ecc0SJérôme Glisse copy_highpage(newpage, page); 6222916ecc0SJérôme Glisse 6232916ecc0SJérôme Glisse migrate_page_states(newpage, page); 6242916ecc0SJérôme Glisse } 6251118dce7SRichard Weinberger EXPORT_SYMBOL(migrate_page_copy); 626b20a3503SChristoph Lameter 6271d8b85ccSChristoph Lameter /************************************************************ 6281d8b85ccSChristoph Lameter * Migration functions 6291d8b85ccSChristoph Lameter ***********************************************************/ 6301d8b85ccSChristoph Lameter 631b20a3503SChristoph Lameter /* 632bda807d4SMinchan Kim * Common logic to directly migrate a single LRU page suitable for 633266cf658SDavid Howells * pages that do not use PagePrivate/PagePrivate2. 634b20a3503SChristoph Lameter * 635b20a3503SChristoph Lameter * Pages are locked upon entry and exit. 636b20a3503SChristoph Lameter */ 6372d1db3b1SChristoph Lameter int migrate_page(struct address_space *mapping, 638a6bc32b8SMel Gorman struct page *newpage, struct page *page, 639a6bc32b8SMel Gorman enum migrate_mode mode) 640b20a3503SChristoph Lameter { 641b20a3503SChristoph Lameter int rc; 642b20a3503SChristoph Lameter 643b20a3503SChristoph Lameter BUG_ON(PageWriteback(page)); /* Writeback must be complete */ 644b20a3503SChristoph Lameter 64537109694SKeith Busch rc = migrate_page_move_mapping(mapping, newpage, page, 0); 646b20a3503SChristoph Lameter 64778bd5209SRafael Aquini if (rc != MIGRATEPAGE_SUCCESS) 648b20a3503SChristoph Lameter return rc; 649b20a3503SChristoph Lameter 6502916ecc0SJérôme Glisse if (mode != MIGRATE_SYNC_NO_COPY) 651b20a3503SChristoph Lameter migrate_page_copy(newpage, page); 6522916ecc0SJérôme Glisse else 6532916ecc0SJérôme Glisse migrate_page_states(newpage, page); 65478bd5209SRafael Aquini return MIGRATEPAGE_SUCCESS; 655b20a3503SChristoph Lameter } 656b20a3503SChristoph Lameter EXPORT_SYMBOL(migrate_page); 657b20a3503SChristoph Lameter 6589361401eSDavid Howells #ifdef CONFIG_BLOCK 65984ade7c1SJan Kara /* Returns true if all buffers are successfully locked */ 66084ade7c1SJan Kara static bool buffer_migrate_lock_buffers(struct buffer_head *head, 66184ade7c1SJan Kara enum migrate_mode mode) 66284ade7c1SJan Kara { 66384ade7c1SJan Kara struct buffer_head *bh = head; 66484ade7c1SJan Kara 66584ade7c1SJan Kara /* Simple case, sync compaction */ 66684ade7c1SJan Kara if (mode != MIGRATE_ASYNC) { 66784ade7c1SJan Kara do { 66884ade7c1SJan Kara lock_buffer(bh); 66984ade7c1SJan Kara bh = bh->b_this_page; 67084ade7c1SJan Kara 67184ade7c1SJan Kara } while (bh != head); 67284ade7c1SJan Kara 67384ade7c1SJan Kara return true; 67484ade7c1SJan Kara } 67584ade7c1SJan Kara 67684ade7c1SJan Kara /* async case, we cannot block on lock_buffer so use trylock_buffer */ 67784ade7c1SJan Kara do { 67884ade7c1SJan Kara if (!trylock_buffer(bh)) { 67984ade7c1SJan Kara /* 68084ade7c1SJan Kara * We failed to lock the buffer and cannot stall in 68184ade7c1SJan Kara * async migration. Release the taken locks 68284ade7c1SJan Kara */ 68384ade7c1SJan Kara struct buffer_head *failed_bh = bh; 68484ade7c1SJan Kara bh = head; 68584ade7c1SJan Kara while (bh != failed_bh) { 68684ade7c1SJan Kara unlock_buffer(bh); 68784ade7c1SJan Kara bh = bh->b_this_page; 68884ade7c1SJan Kara } 68984ade7c1SJan Kara return false; 69084ade7c1SJan Kara } 69184ade7c1SJan Kara 69284ade7c1SJan Kara bh = bh->b_this_page; 69384ade7c1SJan Kara } while (bh != head); 69484ade7c1SJan Kara return true; 69584ade7c1SJan Kara } 69684ade7c1SJan Kara 69789cb0888SJan Kara static int __buffer_migrate_page(struct address_space *mapping, 69889cb0888SJan Kara struct page *newpage, struct page *page, enum migrate_mode mode, 69989cb0888SJan Kara bool check_refs) 7001d8b85ccSChristoph Lameter { 7011d8b85ccSChristoph Lameter struct buffer_head *bh, *head; 7021d8b85ccSChristoph Lameter int rc; 703cc4f11e6SJan Kara int expected_count; 7041d8b85ccSChristoph Lameter 7051d8b85ccSChristoph Lameter if (!page_has_buffers(page)) 706a6bc32b8SMel Gorman return migrate_page(mapping, newpage, page, mode); 7071d8b85ccSChristoph Lameter 708cc4f11e6SJan Kara /* Check whether page does not have extra refs before we do more work */ 709f900482dSJan Kara expected_count = expected_page_refs(mapping, page); 710cc4f11e6SJan Kara if (page_count(page) != expected_count) 711cc4f11e6SJan Kara return -EAGAIN; 712cc4f11e6SJan Kara 7131d8b85ccSChristoph Lameter head = page_buffers(page); 714cc4f11e6SJan Kara if (!buffer_migrate_lock_buffers(head, mode)) 715cc4f11e6SJan Kara return -EAGAIN; 7161d8b85ccSChristoph Lameter 71789cb0888SJan Kara if (check_refs) { 71889cb0888SJan Kara bool busy; 71989cb0888SJan Kara bool invalidated = false; 72089cb0888SJan Kara 72189cb0888SJan Kara recheck_buffers: 72289cb0888SJan Kara busy = false; 72389cb0888SJan Kara spin_lock(&mapping->private_lock); 72489cb0888SJan Kara bh = head; 72589cb0888SJan Kara do { 72689cb0888SJan Kara if (atomic_read(&bh->b_count)) { 72789cb0888SJan Kara busy = true; 72889cb0888SJan Kara break; 72989cb0888SJan Kara } 73089cb0888SJan Kara bh = bh->b_this_page; 73189cb0888SJan Kara } while (bh != head); 73289cb0888SJan Kara if (busy) { 73389cb0888SJan Kara if (invalidated) { 73489cb0888SJan Kara rc = -EAGAIN; 73589cb0888SJan Kara goto unlock_buffers; 73689cb0888SJan Kara } 737ebdf4de5SJan Kara spin_unlock(&mapping->private_lock); 73889cb0888SJan Kara invalidate_bh_lrus(); 73989cb0888SJan Kara invalidated = true; 74089cb0888SJan Kara goto recheck_buffers; 74189cb0888SJan Kara } 74289cb0888SJan Kara } 74389cb0888SJan Kara 74437109694SKeith Busch rc = migrate_page_move_mapping(mapping, newpage, page, 0); 74578bd5209SRafael Aquini if (rc != MIGRATEPAGE_SUCCESS) 746cc4f11e6SJan Kara goto unlock_buffers; 7471d8b85ccSChristoph Lameter 748cd0f3715SGuoqing Jiang attach_page_private(newpage, detach_page_private(page)); 7491d8b85ccSChristoph Lameter 7501d8b85ccSChristoph Lameter bh = head; 7511d8b85ccSChristoph Lameter do { 7521d8b85ccSChristoph Lameter set_bh_page(bh, newpage, bh_offset(bh)); 7531d8b85ccSChristoph Lameter bh = bh->b_this_page; 7541d8b85ccSChristoph Lameter 7551d8b85ccSChristoph Lameter } while (bh != head); 7561d8b85ccSChristoph Lameter 7572916ecc0SJérôme Glisse if (mode != MIGRATE_SYNC_NO_COPY) 7581d8b85ccSChristoph Lameter migrate_page_copy(newpage, page); 7592916ecc0SJérôme Glisse else 7602916ecc0SJérôme Glisse migrate_page_states(newpage, page); 7611d8b85ccSChristoph Lameter 762cc4f11e6SJan Kara rc = MIGRATEPAGE_SUCCESS; 763cc4f11e6SJan Kara unlock_buffers: 764ebdf4de5SJan Kara if (check_refs) 765ebdf4de5SJan Kara spin_unlock(&mapping->private_lock); 7661d8b85ccSChristoph Lameter bh = head; 7671d8b85ccSChristoph Lameter do { 7681d8b85ccSChristoph Lameter unlock_buffer(bh); 7691d8b85ccSChristoph Lameter bh = bh->b_this_page; 7701d8b85ccSChristoph Lameter 7711d8b85ccSChristoph Lameter } while (bh != head); 7721d8b85ccSChristoph Lameter 773cc4f11e6SJan Kara return rc; 7741d8b85ccSChristoph Lameter } 77589cb0888SJan Kara 77689cb0888SJan Kara /* 77789cb0888SJan Kara * Migration function for pages with buffers. This function can only be used 77889cb0888SJan Kara * if the underlying filesystem guarantees that no other references to "page" 77989cb0888SJan Kara * exist. For example attached buffer heads are accessed only under page lock. 78089cb0888SJan Kara */ 78189cb0888SJan Kara int buffer_migrate_page(struct address_space *mapping, 78289cb0888SJan Kara struct page *newpage, struct page *page, enum migrate_mode mode) 78389cb0888SJan Kara { 78489cb0888SJan Kara return __buffer_migrate_page(mapping, newpage, page, mode, false); 78589cb0888SJan Kara } 7861d8b85ccSChristoph Lameter EXPORT_SYMBOL(buffer_migrate_page); 78789cb0888SJan Kara 78889cb0888SJan Kara /* 78989cb0888SJan Kara * Same as above except that this variant is more careful and checks that there 79089cb0888SJan Kara * are also no buffer head references. This function is the right one for 79189cb0888SJan Kara * mappings where buffer heads are directly looked up and referenced (such as 79289cb0888SJan Kara * block device mappings). 79389cb0888SJan Kara */ 79489cb0888SJan Kara int buffer_migrate_page_norefs(struct address_space *mapping, 79589cb0888SJan Kara struct page *newpage, struct page *page, enum migrate_mode mode) 79689cb0888SJan Kara { 79789cb0888SJan Kara return __buffer_migrate_page(mapping, newpage, page, mode, true); 79889cb0888SJan Kara } 7999361401eSDavid Howells #endif 8001d8b85ccSChristoph Lameter 80104e62a29SChristoph Lameter /* 80204e62a29SChristoph Lameter * Writeback a page to clean the dirty state 80304e62a29SChristoph Lameter */ 80404e62a29SChristoph Lameter static int writeout(struct address_space *mapping, struct page *page) 80504e62a29SChristoph Lameter { 80604e62a29SChristoph Lameter struct writeback_control wbc = { 80704e62a29SChristoph Lameter .sync_mode = WB_SYNC_NONE, 80804e62a29SChristoph Lameter .nr_to_write = 1, 80904e62a29SChristoph Lameter .range_start = 0, 81004e62a29SChristoph Lameter .range_end = LLONG_MAX, 81104e62a29SChristoph Lameter .for_reclaim = 1 81204e62a29SChristoph Lameter }; 81304e62a29SChristoph Lameter int rc; 81404e62a29SChristoph Lameter 81504e62a29SChristoph Lameter if (!mapping->a_ops->writepage) 81604e62a29SChristoph Lameter /* No write method for the address space */ 81704e62a29SChristoph Lameter return -EINVAL; 81804e62a29SChristoph Lameter 81904e62a29SChristoph Lameter if (!clear_page_dirty_for_io(page)) 82004e62a29SChristoph Lameter /* Someone else already triggered a write */ 82104e62a29SChristoph Lameter return -EAGAIN; 82204e62a29SChristoph Lameter 82304e62a29SChristoph Lameter /* 82404e62a29SChristoph Lameter * A dirty page may imply that the underlying filesystem has 82504e62a29SChristoph Lameter * the page on some queue. So the page must be clean for 82604e62a29SChristoph Lameter * migration. Writeout may mean we loose the lock and the 82704e62a29SChristoph Lameter * page state is no longer what we checked for earlier. 82804e62a29SChristoph Lameter * At this point we know that the migration attempt cannot 82904e62a29SChristoph Lameter * be successful. 83004e62a29SChristoph Lameter */ 831e388466dSKirill A. Shutemov remove_migration_ptes(page, page, false); 83204e62a29SChristoph Lameter 83304e62a29SChristoph Lameter rc = mapping->a_ops->writepage(page, &wbc); 83404e62a29SChristoph Lameter 83504e62a29SChristoph Lameter if (rc != AOP_WRITEPAGE_ACTIVATE) 83604e62a29SChristoph Lameter /* unlocked. Relock */ 83704e62a29SChristoph Lameter lock_page(page); 83804e62a29SChristoph Lameter 839bda8550dSHugh Dickins return (rc < 0) ? -EIO : -EAGAIN; 84004e62a29SChristoph Lameter } 84104e62a29SChristoph Lameter 84204e62a29SChristoph Lameter /* 84304e62a29SChristoph Lameter * Default handling if a filesystem does not provide a migration function. 84404e62a29SChristoph Lameter */ 8458351a6e4SChristoph Lameter static int fallback_migrate_page(struct address_space *mapping, 846a6bc32b8SMel Gorman struct page *newpage, struct page *page, enum migrate_mode mode) 8478351a6e4SChristoph Lameter { 848b969c4abSMel Gorman if (PageDirty(page)) { 849a6bc32b8SMel Gorman /* Only writeback pages in full synchronous migration */ 8502916ecc0SJérôme Glisse switch (mode) { 8512916ecc0SJérôme Glisse case MIGRATE_SYNC: 8522916ecc0SJérôme Glisse case MIGRATE_SYNC_NO_COPY: 8532916ecc0SJérôme Glisse break; 8542916ecc0SJérôme Glisse default: 855b969c4abSMel Gorman return -EBUSY; 8562916ecc0SJérôme Glisse } 85704e62a29SChristoph Lameter return writeout(mapping, page); 858b969c4abSMel Gorman } 8598351a6e4SChristoph Lameter 8608351a6e4SChristoph Lameter /* 8618351a6e4SChristoph Lameter * Buffers may be managed in a filesystem specific way. 8628351a6e4SChristoph Lameter * We must have no buffers or drop them. 8638351a6e4SChristoph Lameter */ 864266cf658SDavid Howells if (page_has_private(page) && 8658351a6e4SChristoph Lameter !try_to_release_page(page, GFP_KERNEL)) 866806031bbSMel Gorman return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY; 8678351a6e4SChristoph Lameter 868a6bc32b8SMel Gorman return migrate_page(mapping, newpage, page, mode); 8698351a6e4SChristoph Lameter } 8708351a6e4SChristoph Lameter 8711d8b85ccSChristoph Lameter /* 872e24f0b8fSChristoph Lameter * Move a page to a newly allocated page 873e24f0b8fSChristoph Lameter * The page is locked and all ptes have been successfully removed. 874b20a3503SChristoph Lameter * 875e24f0b8fSChristoph Lameter * The new page will have replaced the old page if this function 876e24f0b8fSChristoph Lameter * is successful. 877894bc310SLee Schermerhorn * 878894bc310SLee Schermerhorn * Return value: 879894bc310SLee Schermerhorn * < 0 - error code 88078bd5209SRafael Aquini * MIGRATEPAGE_SUCCESS - success 881b20a3503SChristoph Lameter */ 8823fe2011fSMel Gorman static int move_to_new_page(struct page *newpage, struct page *page, 8835c3f9a67SHugh Dickins enum migrate_mode mode) 884b20a3503SChristoph Lameter { 885e24f0b8fSChristoph Lameter struct address_space *mapping; 886bda807d4SMinchan Kim int rc = -EAGAIN; 887bda807d4SMinchan Kim bool is_lru = !__PageMovable(page); 888b20a3503SChristoph Lameter 8897db7671fSHugh Dickins VM_BUG_ON_PAGE(!PageLocked(page), page); 8907db7671fSHugh Dickins VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); 891b20a3503SChristoph Lameter 892b20a3503SChristoph Lameter mapping = page_mapping(page); 893bda807d4SMinchan Kim 894bda807d4SMinchan Kim if (likely(is_lru)) { 895b20a3503SChristoph Lameter if (!mapping) 896a6bc32b8SMel Gorman rc = migrate_page(mapping, newpage, page, mode); 8976c5240aeSChristoph Lameter else if (mapping->a_ops->migratepage) 898b20a3503SChristoph Lameter /* 899bda807d4SMinchan Kim * Most pages have a mapping and most filesystems 900bda807d4SMinchan Kim * provide a migratepage callback. Anonymous pages 901bda807d4SMinchan Kim * are part of swap space which also has its own 902bda807d4SMinchan Kim * migratepage callback. This is the most common path 903bda807d4SMinchan Kim * for page migration. 904b20a3503SChristoph Lameter */ 905bda807d4SMinchan Kim rc = mapping->a_ops->migratepage(mapping, newpage, 906bda807d4SMinchan Kim page, mode); 9078351a6e4SChristoph Lameter else 908bda807d4SMinchan Kim rc = fallback_migrate_page(mapping, newpage, 909bda807d4SMinchan Kim page, mode); 910bda807d4SMinchan Kim } else { 911bda807d4SMinchan Kim /* 912bda807d4SMinchan Kim * In case of non-lru page, it could be released after 913bda807d4SMinchan Kim * isolation step. In that case, we shouldn't try migration. 914bda807d4SMinchan Kim */ 915bda807d4SMinchan Kim VM_BUG_ON_PAGE(!PageIsolated(page), page); 916bda807d4SMinchan Kim if (!PageMovable(page)) { 917bda807d4SMinchan Kim rc = MIGRATEPAGE_SUCCESS; 918bda807d4SMinchan Kim __ClearPageIsolated(page); 919bda807d4SMinchan Kim goto out; 920bda807d4SMinchan Kim } 921bda807d4SMinchan Kim 922bda807d4SMinchan Kim rc = mapping->a_ops->migratepage(mapping, newpage, 923bda807d4SMinchan Kim page, mode); 924bda807d4SMinchan Kim WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS && 925bda807d4SMinchan Kim !PageIsolated(page)); 926bda807d4SMinchan Kim } 927b20a3503SChristoph Lameter 9285c3f9a67SHugh Dickins /* 9295c3f9a67SHugh Dickins * When successful, old pagecache page->mapping must be cleared before 9305c3f9a67SHugh Dickins * page is freed; but stats require that PageAnon be left as PageAnon. 9315c3f9a67SHugh Dickins */ 9325c3f9a67SHugh Dickins if (rc == MIGRATEPAGE_SUCCESS) { 933bda807d4SMinchan Kim if (__PageMovable(page)) { 934bda807d4SMinchan Kim VM_BUG_ON_PAGE(!PageIsolated(page), page); 935bda807d4SMinchan Kim 936bda807d4SMinchan Kim /* 937bda807d4SMinchan Kim * We clear PG_movable under page_lock so any compactor 938bda807d4SMinchan Kim * cannot try to migrate this page. 939bda807d4SMinchan Kim */ 940bda807d4SMinchan Kim __ClearPageIsolated(page); 941bda807d4SMinchan Kim } 942bda807d4SMinchan Kim 943bda807d4SMinchan Kim /* 944c23a0c99SRalph Campbell * Anonymous and movable page->mapping will be cleared by 945bda807d4SMinchan Kim * free_pages_prepare so don't reset it here for keeping 946bda807d4SMinchan Kim * the type to work PageAnon, for example. 947bda807d4SMinchan Kim */ 948bda807d4SMinchan Kim if (!PageMappingFlags(page)) 9495c3f9a67SHugh Dickins page->mapping = NULL; 950d2b2c6ddSLars Persson 95125b2995aSChristoph Hellwig if (likely(!is_zone_device_page(newpage))) 952d2b2c6ddSLars Persson flush_dcache_page(newpage); 953d2b2c6ddSLars Persson 9543fe2011fSMel Gorman } 955bda807d4SMinchan Kim out: 956e24f0b8fSChristoph Lameter return rc; 957e24f0b8fSChristoph Lameter } 958e24f0b8fSChristoph Lameter 9590dabec93SMinchan Kim static int __unmap_and_move(struct page *page, struct page *newpage, 9609c620e2bSHugh Dickins int force, enum migrate_mode mode) 961e24f0b8fSChristoph Lameter { 9620dabec93SMinchan Kim int rc = -EAGAIN; 963213ecb31SBaolin Wang bool page_was_mapped = false; 9643f6c8272SMel Gorman struct anon_vma *anon_vma = NULL; 965bda807d4SMinchan Kim bool is_lru = !__PageMovable(page); 96695a402c3SChristoph Lameter 967529ae9aaSNick Piggin if (!trylock_page(page)) { 968a6bc32b8SMel Gorman if (!force || mode == MIGRATE_ASYNC) 9690dabec93SMinchan Kim goto out; 9703e7d3449SMel Gorman 9713e7d3449SMel Gorman /* 9723e7d3449SMel Gorman * It's not safe for direct compaction to call lock_page. 9733e7d3449SMel Gorman * For example, during page readahead pages are added locked 9743e7d3449SMel Gorman * to the LRU. Later, when the IO completes the pages are 9753e7d3449SMel Gorman * marked uptodate and unlocked. However, the queueing 9763e7d3449SMel Gorman * could be merging multiple pages for one bio (e.g. 977d4388340SMatthew Wilcox (Oracle) * mpage_readahead). If an allocation happens for the 9783e7d3449SMel Gorman * second or third page, the process can end up locking 9793e7d3449SMel Gorman * the same page twice and deadlocking. Rather than 9803e7d3449SMel Gorman * trying to be clever about what pages can be locked, 9813e7d3449SMel Gorman * avoid the use of lock_page for direct compaction 9823e7d3449SMel Gorman * altogether. 9833e7d3449SMel Gorman */ 9843e7d3449SMel Gorman if (current->flags & PF_MEMALLOC) 9850dabec93SMinchan Kim goto out; 9863e7d3449SMel Gorman 987e24f0b8fSChristoph Lameter lock_page(page); 988e24f0b8fSChristoph Lameter } 989e24f0b8fSChristoph Lameter 990e24f0b8fSChristoph Lameter if (PageWriteback(page)) { 99111bc82d6SAndrea Arcangeli /* 992fed5b64aSJianguo Wu * Only in the case of a full synchronous migration is it 993a6bc32b8SMel Gorman * necessary to wait for PageWriteback. In the async case, 994a6bc32b8SMel Gorman * the retry loop is too short and in the sync-light case, 995a6bc32b8SMel Gorman * the overhead of stalling is too much 99611bc82d6SAndrea Arcangeli */ 9972916ecc0SJérôme Glisse switch (mode) { 9982916ecc0SJérôme Glisse case MIGRATE_SYNC: 9992916ecc0SJérôme Glisse case MIGRATE_SYNC_NO_COPY: 10002916ecc0SJérôme Glisse break; 10012916ecc0SJérôme Glisse default: 100211bc82d6SAndrea Arcangeli rc = -EBUSY; 10030a31bc97SJohannes Weiner goto out_unlock; 100411bc82d6SAndrea Arcangeli } 100511bc82d6SAndrea Arcangeli if (!force) 10060a31bc97SJohannes Weiner goto out_unlock; 1007e24f0b8fSChristoph Lameter wait_on_page_writeback(page); 1008e24f0b8fSChristoph Lameter } 100903f15c86SHugh Dickins 1010e24f0b8fSChristoph Lameter /* 101168a9843fSBaolin Wang * By try_to_migrate(), page->mapcount goes down to 0 here. In this case, 1012dc386d4dSKAMEZAWA Hiroyuki * we cannot notice that anon_vma is freed while we migrates a page. 10131ce82b69SHugh Dickins * This get_anon_vma() delays freeing anon_vma pointer until the end 1014dc386d4dSKAMEZAWA Hiroyuki * of migration. File cache pages are no problem because of page_lock() 1015989f89c5SKAMEZAWA Hiroyuki * File Caches may use write_page() or lock_page() in migration, then, 1016989f89c5SKAMEZAWA Hiroyuki * just care Anon page here. 10173fe2011fSMel Gorman * 101803f15c86SHugh Dickins * Only page_get_anon_vma() understands the subtleties of 101903f15c86SHugh Dickins * getting a hold on an anon_vma from outside one of its mms. 102003f15c86SHugh Dickins * But if we cannot get anon_vma, then we won't need it anyway, 102103f15c86SHugh Dickins * because that implies that the anon page is no longer mapped 102203f15c86SHugh Dickins * (and cannot be remapped so long as we hold the page lock). 10233fe2011fSMel Gorman */ 102403f15c86SHugh Dickins if (PageAnon(page) && !PageKsm(page)) 102503f15c86SHugh Dickins anon_vma = page_get_anon_vma(page); 102662e1c553SShaohua Li 10277db7671fSHugh Dickins /* 10287db7671fSHugh Dickins * Block others from accessing the new page when we get around to 10297db7671fSHugh Dickins * establishing additional references. We are usually the only one 10307db7671fSHugh Dickins * holding a reference to newpage at this point. We used to have a BUG 10317db7671fSHugh Dickins * here if trylock_page(newpage) fails, but would like to allow for 10327db7671fSHugh Dickins * cases where there might be a race with the previous use of newpage. 10337db7671fSHugh Dickins * This is much like races on refcount of oldpage: just don't BUG(). 10347db7671fSHugh Dickins */ 10357db7671fSHugh Dickins if (unlikely(!trylock_page(newpage))) 10367db7671fSHugh Dickins goto out_unlock; 10377db7671fSHugh Dickins 1038bda807d4SMinchan Kim if (unlikely(!is_lru)) { 1039bda807d4SMinchan Kim rc = move_to_new_page(newpage, page, mode); 1040bda807d4SMinchan Kim goto out_unlock_both; 1041bda807d4SMinchan Kim } 1042bda807d4SMinchan Kim 1043dc386d4dSKAMEZAWA Hiroyuki /* 104462e1c553SShaohua Li * Corner case handling: 104562e1c553SShaohua Li * 1. When a new swap-cache page is read into, it is added to the LRU 104662e1c553SShaohua Li * and treated as swapcache but it has no rmap yet. 104762e1c553SShaohua Li * Calling try_to_unmap() against a page->mapping==NULL page will 104862e1c553SShaohua Li * trigger a BUG. So handle it here. 1049d12b8951SYang Shi * 2. An orphaned page (see truncate_cleanup_page) might have 105062e1c553SShaohua Li * fs-private metadata. The page can be picked up due to memory 105162e1c553SShaohua Li * offlining. Everywhere else except page reclaim, the page is 105262e1c553SShaohua Li * invisible to the vm, so the page can not be migrated. So try to 105362e1c553SShaohua Li * free the metadata, so the page can be freed. 1054dc386d4dSKAMEZAWA Hiroyuki */ 105562e1c553SShaohua Li if (!page->mapping) { 1056309381feSSasha Levin VM_BUG_ON_PAGE(PageAnon(page), page); 10571ce82b69SHugh Dickins if (page_has_private(page)) { 105862e1c553SShaohua Li try_to_free_buffers(page); 10597db7671fSHugh Dickins goto out_unlock_both; 106062e1c553SShaohua Li } 10617db7671fSHugh Dickins } else if (page_mapped(page)) { 10627db7671fSHugh Dickins /* Establish migration ptes */ 106303f15c86SHugh Dickins VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma, 106403f15c86SHugh Dickins page); 1065a98a2f0cSAlistair Popple try_to_migrate(page, 0); 1066213ecb31SBaolin Wang page_was_mapped = true; 10672ebba6b7SHugh Dickins } 1068dc386d4dSKAMEZAWA Hiroyuki 1069e24f0b8fSChristoph Lameter if (!page_mapped(page)) 10705c3f9a67SHugh Dickins rc = move_to_new_page(newpage, page, mode); 1071e24f0b8fSChristoph Lameter 10725c3f9a67SHugh Dickins if (page_was_mapped) 10735c3f9a67SHugh Dickins remove_migration_ptes(page, 1074e388466dSKirill A. Shutemov rc == MIGRATEPAGE_SUCCESS ? newpage : page, false); 10753f6c8272SMel Gorman 10767db7671fSHugh Dickins out_unlock_both: 10777db7671fSHugh Dickins unlock_page(newpage); 10787db7671fSHugh Dickins out_unlock: 10793f6c8272SMel Gorman /* Drop an anon_vma reference if we took one */ 108076545066SRik van Riel if (anon_vma) 10819e60109fSPeter Zijlstra put_anon_vma(anon_vma); 1082b20a3503SChristoph Lameter unlock_page(page); 10830dabec93SMinchan Kim out: 1084c6c919ebSMinchan Kim /* 1085c6c919ebSMinchan Kim * If migration is successful, decrease refcount of the newpage 1086c6c919ebSMinchan Kim * which will not free the page because new page owner increased 1087c6c919ebSMinchan Kim * refcounter. As well, if it is LRU page, add the page to LRU 1088e0a352faSDavid Hildenbrand * list in here. Use the old state of the isolated source page to 1089e0a352faSDavid Hildenbrand * determine if we migrated a LRU page. newpage was already unlocked 1090e0a352faSDavid Hildenbrand * and possibly modified by its owner - don't rely on the page 1091e0a352faSDavid Hildenbrand * state. 1092c6c919ebSMinchan Kim */ 1093c6c919ebSMinchan Kim if (rc == MIGRATEPAGE_SUCCESS) { 1094e0a352faSDavid Hildenbrand if (unlikely(!is_lru)) 1095c6c919ebSMinchan Kim put_page(newpage); 1096c6c919ebSMinchan Kim else 1097c6c919ebSMinchan Kim putback_lru_page(newpage); 1098c6c919ebSMinchan Kim } 1099c6c919ebSMinchan Kim 11000dabec93SMinchan Kim return rc; 11010dabec93SMinchan Kim } 110295a402c3SChristoph Lameter 110379c28a41SDave Hansen 110479c28a41SDave Hansen /* 110579c28a41SDave Hansen * node_demotion[] example: 110679c28a41SDave Hansen * 110779c28a41SDave Hansen * Consider a system with two sockets. Each socket has 110879c28a41SDave Hansen * three classes of memory attached: fast, medium and slow. 110979c28a41SDave Hansen * Each memory class is placed in its own NUMA node. The 111079c28a41SDave Hansen * CPUs are placed in the node with the "fast" memory. The 111179c28a41SDave Hansen * 6 NUMA nodes (0-5) might be split among the sockets like 111279c28a41SDave Hansen * this: 111379c28a41SDave Hansen * 111479c28a41SDave Hansen * Socket A: 0, 1, 2 111579c28a41SDave Hansen * Socket B: 3, 4, 5 111679c28a41SDave Hansen * 111779c28a41SDave Hansen * When Node 0 fills up, its memory should be migrated to 111879c28a41SDave Hansen * Node 1. When Node 1 fills up, it should be migrated to 111979c28a41SDave Hansen * Node 2. The migration path start on the nodes with the 112079c28a41SDave Hansen * processors (since allocations default to this node) and 112179c28a41SDave Hansen * fast memory, progress through medium and end with the 112279c28a41SDave Hansen * slow memory: 112379c28a41SDave Hansen * 112479c28a41SDave Hansen * 0 -> 1 -> 2 -> stop 112579c28a41SDave Hansen * 3 -> 4 -> 5 -> stop 112679c28a41SDave Hansen * 112779c28a41SDave Hansen * This is represented in the node_demotion[] like this: 112879c28a41SDave Hansen * 112979c28a41SDave Hansen * { 1, // Node 0 migrates to 1 113079c28a41SDave Hansen * 2, // Node 1 migrates to 2 113179c28a41SDave Hansen * -1, // Node 2 does not migrate 113279c28a41SDave Hansen * 4, // Node 3 migrates to 4 113379c28a41SDave Hansen * 5, // Node 4 migrates to 5 113479c28a41SDave Hansen * -1} // Node 5 does not migrate 113579c28a41SDave Hansen */ 113679c28a41SDave Hansen 113779c28a41SDave Hansen /* 113879c28a41SDave Hansen * Writes to this array occur without locking. Cycles are 113979c28a41SDave Hansen * not allowed: Node X demotes to Y which demotes to X... 114079c28a41SDave Hansen * 114179c28a41SDave Hansen * If multiple reads are performed, a single rcu_read_lock() 114279c28a41SDave Hansen * must be held over all reads to ensure that no cycles are 114379c28a41SDave Hansen * observed. 114479c28a41SDave Hansen */ 114579c28a41SDave Hansen static int node_demotion[MAX_NUMNODES] __read_mostly = 114679c28a41SDave Hansen {[0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE}; 114779c28a41SDave Hansen 114879c28a41SDave Hansen /** 114979c28a41SDave Hansen * next_demotion_node() - Get the next node in the demotion path 115079c28a41SDave Hansen * @node: The starting node to lookup the next node 115179c28a41SDave Hansen * 1152c9bd7d18SRandy Dunlap * Return: node id for next memory node in the demotion path hierarchy 115379c28a41SDave Hansen * from @node; NUMA_NO_NODE if @node is terminal. This does not keep 115479c28a41SDave Hansen * @node online or guarantee that it *continues* to be the next demotion 115579c28a41SDave Hansen * target. 115679c28a41SDave Hansen */ 115779c28a41SDave Hansen int next_demotion_node(int node) 115879c28a41SDave Hansen { 115979c28a41SDave Hansen int target; 116079c28a41SDave Hansen 116179c28a41SDave Hansen /* 116279c28a41SDave Hansen * node_demotion[] is updated without excluding this 116379c28a41SDave Hansen * function from running. RCU doesn't provide any 116479c28a41SDave Hansen * compiler barriers, so the READ_ONCE() is required 116579c28a41SDave Hansen * to avoid compiler reordering or read merging. 116679c28a41SDave Hansen * 116779c28a41SDave Hansen * Make sure to use RCU over entire code blocks if 116879c28a41SDave Hansen * node_demotion[] reads need to be consistent. 116979c28a41SDave Hansen */ 117079c28a41SDave Hansen rcu_read_lock(); 117179c28a41SDave Hansen target = READ_ONCE(node_demotion[node]); 117279c28a41SDave Hansen rcu_read_unlock(); 117379c28a41SDave Hansen 117479c28a41SDave Hansen return target; 117579c28a41SDave Hansen } 117679c28a41SDave Hansen 11770dabec93SMinchan Kim /* 11780dabec93SMinchan Kim * Obtain the lock on page, remove all ptes and migrate the page 11790dabec93SMinchan Kim * to the newly allocated page in newpage. 11800dabec93SMinchan Kim */ 11816ec4476aSLinus Torvalds static int unmap_and_move(new_page_t get_new_page, 1182ef2a5153SGeert Uytterhoeven free_page_t put_new_page, 1183ef2a5153SGeert Uytterhoeven unsigned long private, struct page *page, 1184add05cecSNaoya Horiguchi int force, enum migrate_mode mode, 1185dd4ae78aSYang Shi enum migrate_reason reason, 1186dd4ae78aSYang Shi struct list_head *ret) 11870dabec93SMinchan Kim { 11882def7424SHugh Dickins int rc = MIGRATEPAGE_SUCCESS; 118974d4a579SYang Shi struct page *newpage = NULL; 11900dabec93SMinchan Kim 119194723aafSMichal Hocko if (!thp_migration_supported() && PageTransHuge(page)) 1192d532e2e5SYang Shi return -ENOSYS; 119394723aafSMichal Hocko 11940dabec93SMinchan Kim if (page_count(page) == 1) { 11950dabec93SMinchan Kim /* page was freed from under us. So we are done. */ 1196c6c919ebSMinchan Kim ClearPageActive(page); 1197c6c919ebSMinchan Kim ClearPageUnevictable(page); 1198bda807d4SMinchan Kim if (unlikely(__PageMovable(page))) { 1199bda807d4SMinchan Kim lock_page(page); 1200bda807d4SMinchan Kim if (!PageMovable(page)) 1201bda807d4SMinchan Kim __ClearPageIsolated(page); 1202bda807d4SMinchan Kim unlock_page(page); 1203bda807d4SMinchan Kim } 12040dabec93SMinchan Kim goto out; 12050dabec93SMinchan Kim } 12060dabec93SMinchan Kim 120774d4a579SYang Shi newpage = get_new_page(page, private); 120874d4a579SYang Shi if (!newpage) 120974d4a579SYang Shi return -ENOMEM; 121074d4a579SYang Shi 12119c620e2bSHugh Dickins rc = __unmap_and_move(page, newpage, force, mode); 1212c6c919ebSMinchan Kim if (rc == MIGRATEPAGE_SUCCESS) 12137cd12b4aSVlastimil Babka set_page_owner_migrate_reason(newpage, reason); 1214bf6bddf1SRafael Aquini 12150dabec93SMinchan Kim out: 1216e24f0b8fSChristoph Lameter if (rc != -EAGAIN) { 1217aaa994b3SChristoph Lameter /* 1218aaa994b3SChristoph Lameter * A page that has been migrated has all references 1219aaa994b3SChristoph Lameter * removed and will be freed. A page that has not been 1220c23a0c99SRalph Campbell * migrated will have kept its references and be restored. 1221aaa994b3SChristoph Lameter */ 1222aaa994b3SChristoph Lameter list_del(&page->lru); 1223e24f0b8fSChristoph Lameter } 122468711a74SDavid Rientjes 122595a402c3SChristoph Lameter /* 1226c6c919ebSMinchan Kim * If migration is successful, releases reference grabbed during 1227c6c919ebSMinchan Kim * isolation. Otherwise, restore the page to right list unless 1228c6c919ebSMinchan Kim * we want to retry. 122995a402c3SChristoph Lameter */ 1230c6c919ebSMinchan Kim if (rc == MIGRATEPAGE_SUCCESS) { 1231dd4ae78aSYang Shi /* 1232dd4ae78aSYang Shi * Compaction can migrate also non-LRU pages which are 1233dd4ae78aSYang Shi * not accounted to NR_ISOLATED_*. They can be recognized 1234dd4ae78aSYang Shi * as __PageMovable 1235dd4ae78aSYang Shi */ 1236dd4ae78aSYang Shi if (likely(!__PageMovable(page))) 1237dd4ae78aSYang Shi mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + 1238dd4ae78aSYang Shi page_is_file_lru(page), -thp_nr_pages(page)); 1239dd4ae78aSYang Shi 124079f5f8faSOscar Salvador if (reason != MR_MEMORY_FAILURE) 1241c6c919ebSMinchan Kim /* 124279f5f8faSOscar Salvador * We release the page in page_handle_poison. 1243c6c919ebSMinchan Kim */ 124479f5f8faSOscar Salvador put_page(page); 1245c6c919ebSMinchan Kim } else { 1246dd4ae78aSYang Shi if (rc != -EAGAIN) 1247dd4ae78aSYang Shi list_add_tail(&page->lru, ret); 1248bda807d4SMinchan Kim 1249cf4b769aSHugh Dickins if (put_new_page) 125068711a74SDavid Rientjes put_new_page(newpage, private); 1251c6c919ebSMinchan Kim else 1252d6d86c0aSKonstantin Khlebnikov put_page(newpage); 1253c6c919ebSMinchan Kim } 125468711a74SDavid Rientjes 1255e24f0b8fSChristoph Lameter return rc; 1256e24f0b8fSChristoph Lameter } 1257b20a3503SChristoph Lameter 1258e24f0b8fSChristoph Lameter /* 1259290408d4SNaoya Horiguchi * Counterpart of unmap_and_move_page() for hugepage migration. 1260290408d4SNaoya Horiguchi * 1261290408d4SNaoya Horiguchi * This function doesn't wait the completion of hugepage I/O 1262290408d4SNaoya Horiguchi * because there is no race between I/O and migration for hugepage. 1263290408d4SNaoya Horiguchi * Note that currently hugepage I/O occurs only in direct I/O 1264290408d4SNaoya Horiguchi * where no lock is held and PG_writeback is irrelevant, 1265290408d4SNaoya Horiguchi * and writeback status of all subpages are counted in the reference 1266290408d4SNaoya Horiguchi * count of the head page (i.e. if all subpages of a 2MB hugepage are 1267290408d4SNaoya Horiguchi * under direct I/O, the reference of the head page is 512 and a bit more.) 1268290408d4SNaoya Horiguchi * This means that when we try to migrate hugepage whose subpages are 1269290408d4SNaoya Horiguchi * doing direct I/O, some references remain after try_to_unmap() and 1270290408d4SNaoya Horiguchi * hugepage migration fails without data corruption. 1271290408d4SNaoya Horiguchi * 1272290408d4SNaoya Horiguchi * There is also no race when direct I/O is issued on the page under migration, 1273290408d4SNaoya Horiguchi * because then pte is replaced with migration swap entry and direct I/O code 1274290408d4SNaoya Horiguchi * will wait in the page fault for migration to complete. 1275290408d4SNaoya Horiguchi */ 1276290408d4SNaoya Horiguchi static int unmap_and_move_huge_page(new_page_t get_new_page, 127768711a74SDavid Rientjes free_page_t put_new_page, unsigned long private, 127868711a74SDavid Rientjes struct page *hpage, int force, 1279dd4ae78aSYang Shi enum migrate_mode mode, int reason, 1280dd4ae78aSYang Shi struct list_head *ret) 1281290408d4SNaoya Horiguchi { 12822def7424SHugh Dickins int rc = -EAGAIN; 12832ebba6b7SHugh Dickins int page_was_mapped = 0; 128432665f2bSJoonsoo Kim struct page *new_hpage; 1285290408d4SNaoya Horiguchi struct anon_vma *anon_vma = NULL; 1286c0d0381aSMike Kravetz struct address_space *mapping = NULL; 1287290408d4SNaoya Horiguchi 128883467efbSNaoya Horiguchi /* 12897ed2c31dSAnshuman Khandual * Migratability of hugepages depends on architectures and their size. 129083467efbSNaoya Horiguchi * This check is necessary because some callers of hugepage migration 129183467efbSNaoya Horiguchi * like soft offline and memory hotremove don't walk through page 129283467efbSNaoya Horiguchi * tables or check whether the hugepage is pmd-based or not before 129383467efbSNaoya Horiguchi * kicking migration. 129483467efbSNaoya Horiguchi */ 1295100873d7SNaoya Horiguchi if (!hugepage_migration_supported(page_hstate(hpage))) { 1296dd4ae78aSYang Shi list_move_tail(&hpage->lru, ret); 129783467efbSNaoya Horiguchi return -ENOSYS; 129832665f2bSJoonsoo Kim } 129983467efbSNaoya Horiguchi 130071a64f61SMuchun Song if (page_count(hpage) == 1) { 130171a64f61SMuchun Song /* page was freed from under us. So we are done. */ 130271a64f61SMuchun Song putback_active_hugepage(hpage); 130371a64f61SMuchun Song return MIGRATEPAGE_SUCCESS; 130471a64f61SMuchun Song } 130571a64f61SMuchun Song 1306666feb21SMichal Hocko new_hpage = get_new_page(hpage, private); 1307290408d4SNaoya Horiguchi if (!new_hpage) 1308290408d4SNaoya Horiguchi return -ENOMEM; 1309290408d4SNaoya Horiguchi 1310290408d4SNaoya Horiguchi if (!trylock_page(hpage)) { 13112916ecc0SJérôme Glisse if (!force) 1312290408d4SNaoya Horiguchi goto out; 13132916ecc0SJérôme Glisse switch (mode) { 13142916ecc0SJérôme Glisse case MIGRATE_SYNC: 13152916ecc0SJérôme Glisse case MIGRATE_SYNC_NO_COPY: 13162916ecc0SJérôme Glisse break; 13172916ecc0SJérôme Glisse default: 13182916ecc0SJérôme Glisse goto out; 13192916ecc0SJérôme Glisse } 1320290408d4SNaoya Horiguchi lock_page(hpage); 1321290408d4SNaoya Horiguchi } 1322290408d4SNaoya Horiguchi 1323cb6acd01SMike Kravetz /* 1324cb6acd01SMike Kravetz * Check for pages which are in the process of being freed. Without 1325cb6acd01SMike Kravetz * page_mapping() set, hugetlbfs specific move page routine will not 1326cb6acd01SMike Kravetz * be called and we could leak usage counts for subpools. 1327cb6acd01SMike Kravetz */ 13286acfb5baSMuchun Song if (hugetlb_page_subpool(hpage) && !page_mapping(hpage)) { 1329cb6acd01SMike Kravetz rc = -EBUSY; 1330cb6acd01SMike Kravetz goto out_unlock; 1331cb6acd01SMike Kravetz } 1332cb6acd01SMike Kravetz 1333746b18d4SPeter Zijlstra if (PageAnon(hpage)) 1334746b18d4SPeter Zijlstra anon_vma = page_get_anon_vma(hpage); 1335290408d4SNaoya Horiguchi 13367db7671fSHugh Dickins if (unlikely(!trylock_page(new_hpage))) 13377db7671fSHugh Dickins goto put_anon; 13387db7671fSHugh Dickins 13392ebba6b7SHugh Dickins if (page_mapped(hpage)) { 1340336bf30eSMike Kravetz bool mapping_locked = false; 1341a98a2f0cSAlistair Popple enum ttu_flags ttu = 0; 1342336bf30eSMike Kravetz 1343336bf30eSMike Kravetz if (!PageAnon(hpage)) { 1344c0d0381aSMike Kravetz /* 1345336bf30eSMike Kravetz * In shared mappings, try_to_unmap could potentially 1346336bf30eSMike Kravetz * call huge_pmd_unshare. Because of this, take 1347336bf30eSMike Kravetz * semaphore in write mode here and set TTU_RMAP_LOCKED 1348336bf30eSMike Kravetz * to let lower levels know we have taken the lock. 1349c0d0381aSMike Kravetz */ 1350c0d0381aSMike Kravetz mapping = hugetlb_page_mapping_lock_write(hpage); 1351c0d0381aSMike Kravetz if (unlikely(!mapping)) 1352c0d0381aSMike Kravetz goto unlock_put_anon; 1353c0d0381aSMike Kravetz 1354336bf30eSMike Kravetz mapping_locked = true; 1355336bf30eSMike Kravetz ttu |= TTU_RMAP_LOCKED; 1356336bf30eSMike Kravetz } 1357336bf30eSMike Kravetz 1358a98a2f0cSAlistair Popple try_to_migrate(hpage, ttu); 13592ebba6b7SHugh Dickins page_was_mapped = 1; 1360336bf30eSMike Kravetz 1361336bf30eSMike Kravetz if (mapping_locked) 1362336bf30eSMike Kravetz i_mmap_unlock_write(mapping); 13632ebba6b7SHugh Dickins } 1364290408d4SNaoya Horiguchi 1365290408d4SNaoya Horiguchi if (!page_mapped(hpage)) 13665c3f9a67SHugh Dickins rc = move_to_new_page(new_hpage, hpage, mode); 1367290408d4SNaoya Horiguchi 1368336bf30eSMike Kravetz if (page_was_mapped) 13695c3f9a67SHugh Dickins remove_migration_ptes(hpage, 1370336bf30eSMike Kravetz rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false); 1371290408d4SNaoya Horiguchi 1372c0d0381aSMike Kravetz unlock_put_anon: 13737db7671fSHugh Dickins unlock_page(new_hpage); 13747db7671fSHugh Dickins 13757db7671fSHugh Dickins put_anon: 1376fd4a4663SHugh Dickins if (anon_vma) 13779e60109fSPeter Zijlstra put_anon_vma(anon_vma); 13788e6ac7faSAneesh Kumar K.V 13792def7424SHugh Dickins if (rc == MIGRATEPAGE_SUCCESS) { 1380ab5ac90aSMichal Hocko move_hugetlb_state(hpage, new_hpage, reason); 13812def7424SHugh Dickins put_new_page = NULL; 13822def7424SHugh Dickins } 13838e6ac7faSAneesh Kumar K.V 1384cb6acd01SMike Kravetz out_unlock: 1385290408d4SNaoya Horiguchi unlock_page(hpage); 138609761333SHillf Danton out: 1387dd4ae78aSYang Shi if (rc == MIGRATEPAGE_SUCCESS) 1388b8ec1ceeSNaoya Horiguchi putback_active_hugepage(hpage); 1389a04840c6SMiaohe Lin else if (rc != -EAGAIN) 1390dd4ae78aSYang Shi list_move_tail(&hpage->lru, ret); 139168711a74SDavid Rientjes 139268711a74SDavid Rientjes /* 139368711a74SDavid Rientjes * If migration was not successful and there's a freeing callback, use 139468711a74SDavid Rientjes * it. Otherwise, put_page() will drop the reference grabbed during 139568711a74SDavid Rientjes * isolation. 139668711a74SDavid Rientjes */ 13972def7424SHugh Dickins if (put_new_page) 139868711a74SDavid Rientjes put_new_page(new_hpage, private); 139968711a74SDavid Rientjes else 14003aaa76e1SNaoya Horiguchi putback_active_hugepage(new_hpage); 140168711a74SDavid Rientjes 1402290408d4SNaoya Horiguchi return rc; 1403290408d4SNaoya Horiguchi } 1404290408d4SNaoya Horiguchi 1405d532e2e5SYang Shi static inline int try_split_thp(struct page *page, struct page **page2, 1406d532e2e5SYang Shi struct list_head *from) 1407d532e2e5SYang Shi { 1408d532e2e5SYang Shi int rc = 0; 1409d532e2e5SYang Shi 1410d532e2e5SYang Shi lock_page(page); 1411d532e2e5SYang Shi rc = split_huge_page_to_list(page, from); 1412d532e2e5SYang Shi unlock_page(page); 1413d532e2e5SYang Shi if (!rc) 1414d532e2e5SYang Shi list_safe_reset_next(page, *page2, lru); 1415d532e2e5SYang Shi 1416d532e2e5SYang Shi return rc; 1417d532e2e5SYang Shi } 1418d532e2e5SYang Shi 1419290408d4SNaoya Horiguchi /* 1420c73e5c9cSSrivatsa S. Bhat * migrate_pages - migrate the pages specified in a list, to the free pages 1421c73e5c9cSSrivatsa S. Bhat * supplied as the target for the page migration 1422e24f0b8fSChristoph Lameter * 1423c73e5c9cSSrivatsa S. Bhat * @from: The list of pages to be migrated. 1424c73e5c9cSSrivatsa S. Bhat * @get_new_page: The function used to allocate free pages to be used 1425c73e5c9cSSrivatsa S. Bhat * as the target of the page migration. 142668711a74SDavid Rientjes * @put_new_page: The function used to free target pages if migration 142768711a74SDavid Rientjes * fails, or NULL if no special handling is necessary. 1428c73e5c9cSSrivatsa S. Bhat * @private: Private data to be passed on to get_new_page() 1429c73e5c9cSSrivatsa S. Bhat * @mode: The migration mode that specifies the constraints for 1430c73e5c9cSSrivatsa S. Bhat * page migration, if any. 1431c73e5c9cSSrivatsa S. Bhat * @reason: The reason for page migration. 14325ac95884SYang Shi * @ret_succeeded: Set to the number of pages migrated successfully if 14335ac95884SYang Shi * the caller passes a non-NULL pointer. 1434e24f0b8fSChristoph Lameter * 1435c73e5c9cSSrivatsa S. Bhat * The function returns after 10 attempts or if no pages are movable any more 1436c73e5c9cSSrivatsa S. Bhat * because the list has become empty or no retryable pages exist any more. 1437dd4ae78aSYang Shi * It is caller's responsibility to call putback_movable_pages() to return pages 1438dd4ae78aSYang Shi * to the LRU or free list only if ret != 0. 1439e24f0b8fSChristoph Lameter * 1440c73e5c9cSSrivatsa S. Bhat * Returns the number of pages that were not migrated, or an error code. 1441e24f0b8fSChristoph Lameter */ 14429c620e2bSHugh Dickins int migrate_pages(struct list_head *from, new_page_t get_new_page, 144368711a74SDavid Rientjes free_page_t put_new_page, unsigned long private, 14445ac95884SYang Shi enum migrate_mode mode, int reason, unsigned int *ret_succeeded) 1445e24f0b8fSChristoph Lameter { 1446e24f0b8fSChristoph Lameter int retry = 1; 14471a5bae25SAnshuman Khandual int thp_retry = 1; 1448e24f0b8fSChristoph Lameter int nr_failed = 0; 14495647bc29SMel Gorman int nr_succeeded = 0; 14501a5bae25SAnshuman Khandual int nr_thp_succeeded = 0; 14511a5bae25SAnshuman Khandual int nr_thp_failed = 0; 14521a5bae25SAnshuman Khandual int nr_thp_split = 0; 1453e24f0b8fSChristoph Lameter int pass = 0; 14541a5bae25SAnshuman Khandual bool is_thp = false; 1455e24f0b8fSChristoph Lameter struct page *page; 1456e24f0b8fSChristoph Lameter struct page *page2; 1457e24f0b8fSChristoph Lameter int swapwrite = current->flags & PF_SWAPWRITE; 14581a5bae25SAnshuman Khandual int rc, nr_subpages; 1459dd4ae78aSYang Shi LIST_HEAD(ret_pages); 1460b0b515bfSYang Shi bool nosplit = (reason == MR_NUMA_MISPLACED); 14612d1db3b1SChristoph Lameter 14627bc1aec5SLiam Mark trace_mm_migrate_pages_start(mode, reason); 14637bc1aec5SLiam Mark 1464e24f0b8fSChristoph Lameter if (!swapwrite) 1465e24f0b8fSChristoph Lameter current->flags |= PF_SWAPWRITE; 1466e24f0b8fSChristoph Lameter 14671a5bae25SAnshuman Khandual for (pass = 0; pass < 10 && (retry || thp_retry); pass++) { 1468e24f0b8fSChristoph Lameter retry = 0; 14691a5bae25SAnshuman Khandual thp_retry = 0; 1470e24f0b8fSChristoph Lameter 1471e24f0b8fSChristoph Lameter list_for_each_entry_safe(page, page2, from, lru) { 147294723aafSMichal Hocko retry: 14731a5bae25SAnshuman Khandual /* 14741a5bae25SAnshuman Khandual * THP statistics is based on the source huge page. 14751a5bae25SAnshuman Khandual * Capture required information that might get lost 14761a5bae25SAnshuman Khandual * during migration. 14771a5bae25SAnshuman Khandual */ 14786c5c7b9fSZi Yan is_thp = PageTransHuge(page) && !PageHuge(page); 14796c357848SMatthew Wilcox (Oracle) nr_subpages = thp_nr_pages(page); 1480e24f0b8fSChristoph Lameter cond_resched(); 1481e24f0b8fSChristoph Lameter 148231caf665SNaoya Horiguchi if (PageHuge(page)) 148331caf665SNaoya Horiguchi rc = unmap_and_move_huge_page(get_new_page, 148468711a74SDavid Rientjes put_new_page, private, page, 1485dd4ae78aSYang Shi pass > 2, mode, reason, 1486dd4ae78aSYang Shi &ret_pages); 148731caf665SNaoya Horiguchi else 148868711a74SDavid Rientjes rc = unmap_and_move(get_new_page, put_new_page, 1489add05cecSNaoya Horiguchi private, page, pass > 2, mode, 1490dd4ae78aSYang Shi reason, &ret_pages); 1491dd4ae78aSYang Shi /* 1492dd4ae78aSYang Shi * The rules are: 1493dd4ae78aSYang Shi * Success: non hugetlb page will be freed, hugetlb 1494dd4ae78aSYang Shi * page will be put back 1495dd4ae78aSYang Shi * -EAGAIN: stay on the from list 1496dd4ae78aSYang Shi * -ENOMEM: stay on the from list 1497dd4ae78aSYang Shi * Other errno: put on ret_pages list then splice to 1498dd4ae78aSYang Shi * from list 1499dd4ae78aSYang Shi */ 1500e24f0b8fSChristoph Lameter switch(rc) { 150194723aafSMichal Hocko /* 150294723aafSMichal Hocko * THP migration might be unsupported or the 150394723aafSMichal Hocko * allocation could've failed so we should 150494723aafSMichal Hocko * retry on the same page with the THP split 150594723aafSMichal Hocko * to base pages. 150694723aafSMichal Hocko * 150794723aafSMichal Hocko * Head page is retried immediately and tail 150894723aafSMichal Hocko * pages are added to the tail of the list so 150994723aafSMichal Hocko * we encounter them after the rest of the list 151094723aafSMichal Hocko * is processed. 151194723aafSMichal Hocko */ 1512d532e2e5SYang Shi case -ENOSYS: 1513d532e2e5SYang Shi /* THP migration is unsupported */ 15146c5c7b9fSZi Yan if (is_thp) { 1515d532e2e5SYang Shi if (!try_split_thp(page, &page2, from)) { 1516d532e2e5SYang Shi nr_thp_split++; 1517d532e2e5SYang Shi goto retry; 1518d532e2e5SYang Shi } 1519d532e2e5SYang Shi 1520d532e2e5SYang Shi nr_thp_failed++; 1521d532e2e5SYang Shi nr_failed += nr_subpages; 1522d532e2e5SYang Shi break; 1523d532e2e5SYang Shi } 1524d532e2e5SYang Shi 1525d532e2e5SYang Shi /* Hugetlb migration is unsupported */ 1526d532e2e5SYang Shi nr_failed++; 1527d532e2e5SYang Shi break; 1528d532e2e5SYang Shi case -ENOMEM: 1529d532e2e5SYang Shi /* 1530d532e2e5SYang Shi * When memory is low, don't bother to try to migrate 1531d532e2e5SYang Shi * other pages, just exit. 1532b0b515bfSYang Shi * THP NUMA faulting doesn't split THP to retry. 1533d532e2e5SYang Shi */ 1534b0b515bfSYang Shi if (is_thp && !nosplit) { 1535d532e2e5SYang Shi if (!try_split_thp(page, &page2, from)) { 15361a5bae25SAnshuman Khandual nr_thp_split++; 153794723aafSMichal Hocko goto retry; 153894723aafSMichal Hocko } 15396c5c7b9fSZi Yan 15401a5bae25SAnshuman Khandual nr_thp_failed++; 15411a5bae25SAnshuman Khandual nr_failed += nr_subpages; 15421a5bae25SAnshuman Khandual goto out; 15431a5bae25SAnshuman Khandual } 1544dfef2ef4SDavid Rientjes nr_failed++; 154595a402c3SChristoph Lameter goto out; 1546e24f0b8fSChristoph Lameter case -EAGAIN: 15471a5bae25SAnshuman Khandual if (is_thp) { 15481a5bae25SAnshuman Khandual thp_retry++; 15491a5bae25SAnshuman Khandual break; 15501a5bae25SAnshuman Khandual } 1551b20a3503SChristoph Lameter retry++; 1552e24f0b8fSChristoph Lameter break; 155378bd5209SRafael Aquini case MIGRATEPAGE_SUCCESS: 15541a5bae25SAnshuman Khandual if (is_thp) { 15551a5bae25SAnshuman Khandual nr_thp_succeeded++; 15561a5bae25SAnshuman Khandual nr_succeeded += nr_subpages; 15571a5bae25SAnshuman Khandual break; 15581a5bae25SAnshuman Khandual } 15595647bc29SMel Gorman nr_succeeded++; 1560e24f0b8fSChristoph Lameter break; 1561e24f0b8fSChristoph Lameter default: 1562354a3363SNaoya Horiguchi /* 1563d532e2e5SYang Shi * Permanent failure (-EBUSY, etc.): 1564354a3363SNaoya Horiguchi * unlike -EAGAIN case, the failed page is 1565354a3363SNaoya Horiguchi * removed from migration page list and not 1566354a3363SNaoya Horiguchi * retried in the next outer loop. 1567354a3363SNaoya Horiguchi */ 15681a5bae25SAnshuman Khandual if (is_thp) { 15691a5bae25SAnshuman Khandual nr_thp_failed++; 15701a5bae25SAnshuman Khandual nr_failed += nr_subpages; 15711a5bae25SAnshuman Khandual break; 15721a5bae25SAnshuman Khandual } 1573b20a3503SChristoph Lameter nr_failed++; 1574e24f0b8fSChristoph Lameter break; 1575b20a3503SChristoph Lameter } 1576b20a3503SChristoph Lameter } 1577e24f0b8fSChristoph Lameter } 15781a5bae25SAnshuman Khandual nr_failed += retry + thp_retry; 15791a5bae25SAnshuman Khandual nr_thp_failed += thp_retry; 1580f2f81fb2SVlastimil Babka rc = nr_failed; 158195a402c3SChristoph Lameter out: 1582dd4ae78aSYang Shi /* 1583dd4ae78aSYang Shi * Put the permanent failure page back to migration list, they 1584dd4ae78aSYang Shi * will be put back to the right list by the caller. 1585dd4ae78aSYang Shi */ 1586dd4ae78aSYang Shi list_splice(&ret_pages, from); 1587dd4ae78aSYang Shi 15885647bc29SMel Gorman count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); 15895647bc29SMel Gorman count_vm_events(PGMIGRATE_FAIL, nr_failed); 15901a5bae25SAnshuman Khandual count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded); 15911a5bae25SAnshuman Khandual count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed); 15921a5bae25SAnshuman Khandual count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split); 15931a5bae25SAnshuman Khandual trace_mm_migrate_pages(nr_succeeded, nr_failed, nr_thp_succeeded, 15941a5bae25SAnshuman Khandual nr_thp_failed, nr_thp_split, mode, reason); 15957b2a2d4aSMel Gorman 1596b20a3503SChristoph Lameter if (!swapwrite) 1597b20a3503SChristoph Lameter current->flags &= ~PF_SWAPWRITE; 1598b20a3503SChristoph Lameter 15995ac95884SYang Shi if (ret_succeeded) 16005ac95884SYang Shi *ret_succeeded = nr_succeeded; 16015ac95884SYang Shi 160295a402c3SChristoph Lameter return rc; 1603b20a3503SChristoph Lameter } 1604b20a3503SChristoph Lameter 160519fc7bedSJoonsoo Kim struct page *alloc_migration_target(struct page *page, unsigned long private) 1606b4b38223SJoonsoo Kim { 160719fc7bedSJoonsoo Kim struct migration_target_control *mtc; 160819fc7bedSJoonsoo Kim gfp_t gfp_mask; 1609b4b38223SJoonsoo Kim unsigned int order = 0; 1610b4b38223SJoonsoo Kim struct page *new_page = NULL; 161119fc7bedSJoonsoo Kim int nid; 161219fc7bedSJoonsoo Kim int zidx; 161319fc7bedSJoonsoo Kim 161419fc7bedSJoonsoo Kim mtc = (struct migration_target_control *)private; 161519fc7bedSJoonsoo Kim gfp_mask = mtc->gfp_mask; 161619fc7bedSJoonsoo Kim nid = mtc->nid; 161719fc7bedSJoonsoo Kim if (nid == NUMA_NO_NODE) 161819fc7bedSJoonsoo Kim nid = page_to_nid(page); 1619b4b38223SJoonsoo Kim 1620d92bbc27SJoonsoo Kim if (PageHuge(page)) { 1621d92bbc27SJoonsoo Kim struct hstate *h = page_hstate(compound_head(page)); 1622d92bbc27SJoonsoo Kim 162319fc7bedSJoonsoo Kim gfp_mask = htlb_modify_alloc_mask(h, gfp_mask); 162419fc7bedSJoonsoo Kim return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask); 1625d92bbc27SJoonsoo Kim } 1626b4b38223SJoonsoo Kim 1627b4b38223SJoonsoo Kim if (PageTransHuge(page)) { 16289933a0c8SJoonsoo Kim /* 16299933a0c8SJoonsoo Kim * clear __GFP_RECLAIM to make the migration callback 16309933a0c8SJoonsoo Kim * consistent with regular THP allocations. 16319933a0c8SJoonsoo Kim */ 16329933a0c8SJoonsoo Kim gfp_mask &= ~__GFP_RECLAIM; 1633b4b38223SJoonsoo Kim gfp_mask |= GFP_TRANSHUGE; 1634b4b38223SJoonsoo Kim order = HPAGE_PMD_ORDER; 1635b4b38223SJoonsoo Kim } 163619fc7bedSJoonsoo Kim zidx = zone_idx(page_zone(page)); 163719fc7bedSJoonsoo Kim if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE) 1638b4b38223SJoonsoo Kim gfp_mask |= __GFP_HIGHMEM; 1639b4b38223SJoonsoo Kim 164084172f4bSMatthew Wilcox (Oracle) new_page = __alloc_pages(gfp_mask, order, nid, mtc->nmask); 1641b4b38223SJoonsoo Kim 1642b4b38223SJoonsoo Kim if (new_page && PageTransHuge(new_page)) 1643b4b38223SJoonsoo Kim prep_transhuge_page(new_page); 1644b4b38223SJoonsoo Kim 1645b4b38223SJoonsoo Kim return new_page; 1646b4b38223SJoonsoo Kim } 1647b4b38223SJoonsoo Kim 1648742755a1SChristoph Lameter #ifdef CONFIG_NUMA 1649742755a1SChristoph Lameter 1650a49bd4d7SMichal Hocko static int store_status(int __user *status, int start, int value, int nr) 1651742755a1SChristoph Lameter { 1652a49bd4d7SMichal Hocko while (nr-- > 0) { 1653a49bd4d7SMichal Hocko if (put_user(value, status + start)) 1654a49bd4d7SMichal Hocko return -EFAULT; 1655a49bd4d7SMichal Hocko start++; 1656a49bd4d7SMichal Hocko } 1657742755a1SChristoph Lameter 1658a49bd4d7SMichal Hocko return 0; 1659a49bd4d7SMichal Hocko } 1660742755a1SChristoph Lameter 1661a49bd4d7SMichal Hocko static int do_move_pages_to_node(struct mm_struct *mm, 1662a49bd4d7SMichal Hocko struct list_head *pagelist, int node) 1663a49bd4d7SMichal Hocko { 1664a49bd4d7SMichal Hocko int err; 1665a0976311SJoonsoo Kim struct migration_target_control mtc = { 1666a0976311SJoonsoo Kim .nid = node, 1667a0976311SJoonsoo Kim .gfp_mask = GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 1668a0976311SJoonsoo Kim }; 1669742755a1SChristoph Lameter 1670a0976311SJoonsoo Kim err = migrate_pages(pagelist, alloc_migration_target, NULL, 16715ac95884SYang Shi (unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL); 1672a49bd4d7SMichal Hocko if (err) 1673a49bd4d7SMichal Hocko putback_movable_pages(pagelist); 1674a49bd4d7SMichal Hocko return err; 1675742755a1SChristoph Lameter } 1676742755a1SChristoph Lameter 1677742755a1SChristoph Lameter /* 1678a49bd4d7SMichal Hocko * Resolves the given address to a struct page, isolates it from the LRU and 1679a49bd4d7SMichal Hocko * puts it to the given pagelist. 1680e0153fc2SYang Shi * Returns: 1681e0153fc2SYang Shi * errno - if the page cannot be found/isolated 1682e0153fc2SYang Shi * 0 - when it doesn't have to be migrated because it is already on the 1683e0153fc2SYang Shi * target node 1684e0153fc2SYang Shi * 1 - when it has been queued 1685742755a1SChristoph Lameter */ 1686a49bd4d7SMichal Hocko static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, 1687a49bd4d7SMichal Hocko int node, struct list_head *pagelist, bool migrate_all) 1688742755a1SChristoph Lameter { 1689742755a1SChristoph Lameter struct vm_area_struct *vma; 1690742755a1SChristoph Lameter struct page *page; 1691e8db67ebSNaoya Horiguchi unsigned int follflags; 1692a49bd4d7SMichal Hocko int err; 1693742755a1SChristoph Lameter 1694d8ed45c5SMichel Lespinasse mmap_read_lock(mm); 1695742755a1SChristoph Lameter err = -EFAULT; 1696a49bd4d7SMichal Hocko vma = find_vma(mm, addr); 1697a49bd4d7SMichal Hocko if (!vma || addr < vma->vm_start || !vma_migratable(vma)) 1698a49bd4d7SMichal Hocko goto out; 1699742755a1SChristoph Lameter 1700d899844eSKirill A. Shutemov /* FOLL_DUMP to ignore special (like zero) pages */ 1701e8db67ebSNaoya Horiguchi follflags = FOLL_GET | FOLL_DUMP; 1702a49bd4d7SMichal Hocko page = follow_page(vma, addr, follflags); 170389f5b7daSLinus Torvalds 170489f5b7daSLinus Torvalds err = PTR_ERR(page); 170589f5b7daSLinus Torvalds if (IS_ERR(page)) 1706a49bd4d7SMichal Hocko goto out; 170789f5b7daSLinus Torvalds 1708742755a1SChristoph Lameter err = -ENOENT; 1709742755a1SChristoph Lameter if (!page) 1710a49bd4d7SMichal Hocko goto out; 1711742755a1SChristoph Lameter 1712a49bd4d7SMichal Hocko err = 0; 1713a49bd4d7SMichal Hocko if (page_to_nid(page) == node) 1714a49bd4d7SMichal Hocko goto out_putpage; 1715742755a1SChristoph Lameter 1716742755a1SChristoph Lameter err = -EACCES; 1717a49bd4d7SMichal Hocko if (page_mapcount(page) > 1 && !migrate_all) 1718a49bd4d7SMichal Hocko goto out_putpage; 1719742755a1SChristoph Lameter 1720e632a938SNaoya Horiguchi if (PageHuge(page)) { 1721e8db67ebSNaoya Horiguchi if (PageHead(page)) { 1722a49bd4d7SMichal Hocko isolate_huge_page(page, pagelist); 1723e0153fc2SYang Shi err = 1; 1724e8db67ebSNaoya Horiguchi } 1725a49bd4d7SMichal Hocko } else { 1726a49bd4d7SMichal Hocko struct page *head; 1727e632a938SNaoya Horiguchi 1728e8db67ebSNaoya Horiguchi head = compound_head(page); 1729e8db67ebSNaoya Horiguchi err = isolate_lru_page(head); 1730a49bd4d7SMichal Hocko if (err) 1731a49bd4d7SMichal Hocko goto out_putpage; 1732a49bd4d7SMichal Hocko 1733e0153fc2SYang Shi err = 1; 1734a49bd4d7SMichal Hocko list_add_tail(&head->lru, pagelist); 1735e8db67ebSNaoya Horiguchi mod_node_page_state(page_pgdat(head), 17369de4f22aSHuang Ying NR_ISOLATED_ANON + page_is_file_lru(head), 17376c357848SMatthew Wilcox (Oracle) thp_nr_pages(head)); 17386d9c285aSKOSAKI Motohiro } 1739a49bd4d7SMichal Hocko out_putpage: 1740742755a1SChristoph Lameter /* 1741742755a1SChristoph Lameter * Either remove the duplicate refcount from 1742742755a1SChristoph Lameter * isolate_lru_page() or drop the page ref if it was 1743742755a1SChristoph Lameter * not isolated. 1744742755a1SChristoph Lameter */ 1745742755a1SChristoph Lameter put_page(page); 1746a49bd4d7SMichal Hocko out: 1747d8ed45c5SMichel Lespinasse mmap_read_unlock(mm); 1748742755a1SChristoph Lameter return err; 1749742755a1SChristoph Lameter } 1750742755a1SChristoph Lameter 17517ca8783aSWei Yang static int move_pages_and_store_status(struct mm_struct *mm, int node, 17527ca8783aSWei Yang struct list_head *pagelist, int __user *status, 17537ca8783aSWei Yang int start, int i, unsigned long nr_pages) 17547ca8783aSWei Yang { 17557ca8783aSWei Yang int err; 17567ca8783aSWei Yang 17575d7ae891SWei Yang if (list_empty(pagelist)) 17585d7ae891SWei Yang return 0; 17595d7ae891SWei Yang 17607ca8783aSWei Yang err = do_move_pages_to_node(mm, pagelist, node); 17617ca8783aSWei Yang if (err) { 17627ca8783aSWei Yang /* 17637ca8783aSWei Yang * Positive err means the number of failed 17647ca8783aSWei Yang * pages to migrate. Since we are going to 17657ca8783aSWei Yang * abort and return the number of non-migrated 1766ab9dd4f8SLong Li * pages, so need to include the rest of the 17677ca8783aSWei Yang * nr_pages that have not been attempted as 17687ca8783aSWei Yang * well. 17697ca8783aSWei Yang */ 17707ca8783aSWei Yang if (err > 0) 17717ca8783aSWei Yang err += nr_pages - i - 1; 17727ca8783aSWei Yang return err; 17737ca8783aSWei Yang } 17747ca8783aSWei Yang return store_status(status, start, node, i - start); 17757ca8783aSWei Yang } 17767ca8783aSWei Yang 1777742755a1SChristoph Lameter /* 17785e9a0f02SBrice Goglin * Migrate an array of page address onto an array of nodes and fill 17795e9a0f02SBrice Goglin * the corresponding array of status. 17805e9a0f02SBrice Goglin */ 17813268c63eSChristoph Lameter static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, 17825e9a0f02SBrice Goglin unsigned long nr_pages, 17835e9a0f02SBrice Goglin const void __user * __user *pages, 17845e9a0f02SBrice Goglin const int __user *nodes, 17855e9a0f02SBrice Goglin int __user *status, int flags) 17865e9a0f02SBrice Goglin { 1787a49bd4d7SMichal Hocko int current_node = NUMA_NO_NODE; 1788a49bd4d7SMichal Hocko LIST_HEAD(pagelist); 1789a49bd4d7SMichal Hocko int start, i; 1790a49bd4d7SMichal Hocko int err = 0, err1; 179135282a2dSBrice Goglin 1792361a2a22SMinchan Kim lru_cache_disable(); 179335282a2dSBrice Goglin 1794a49bd4d7SMichal Hocko for (i = start = 0; i < nr_pages; i++) { 17955e9a0f02SBrice Goglin const void __user *p; 1796a49bd4d7SMichal Hocko unsigned long addr; 17975e9a0f02SBrice Goglin int node; 17985e9a0f02SBrice Goglin 17993140a227SBrice Goglin err = -EFAULT; 1800a49bd4d7SMichal Hocko if (get_user(p, pages + i)) 1801a49bd4d7SMichal Hocko goto out_flush; 1802a49bd4d7SMichal Hocko if (get_user(node, nodes + i)) 1803a49bd4d7SMichal Hocko goto out_flush; 1804057d3389SAndrey Konovalov addr = (unsigned long)untagged_addr(p); 18055e9a0f02SBrice Goglin 18065e9a0f02SBrice Goglin err = -ENODEV; 18076f5a55f1SLinus Torvalds if (node < 0 || node >= MAX_NUMNODES) 1808a49bd4d7SMichal Hocko goto out_flush; 1809389162c2SLai Jiangshan if (!node_state(node, N_MEMORY)) 1810a49bd4d7SMichal Hocko goto out_flush; 18115e9a0f02SBrice Goglin 18125e9a0f02SBrice Goglin err = -EACCES; 18135e9a0f02SBrice Goglin if (!node_isset(node, task_nodes)) 1814a49bd4d7SMichal Hocko goto out_flush; 18155e9a0f02SBrice Goglin 1816a49bd4d7SMichal Hocko if (current_node == NUMA_NO_NODE) { 1817a49bd4d7SMichal Hocko current_node = node; 1818a49bd4d7SMichal Hocko start = i; 1819a49bd4d7SMichal Hocko } else if (node != current_node) { 18207ca8783aSWei Yang err = move_pages_and_store_status(mm, current_node, 18217ca8783aSWei Yang &pagelist, status, start, i, nr_pages); 1822a49bd4d7SMichal Hocko if (err) 1823a49bd4d7SMichal Hocko goto out; 1824a49bd4d7SMichal Hocko start = i; 1825a49bd4d7SMichal Hocko current_node = node; 18265e9a0f02SBrice Goglin } 18275e9a0f02SBrice Goglin 1828a49bd4d7SMichal Hocko /* 1829a49bd4d7SMichal Hocko * Errors in the page lookup or isolation are not fatal and we simply 1830a49bd4d7SMichal Hocko * report them via status 1831a49bd4d7SMichal Hocko */ 1832a49bd4d7SMichal Hocko err = add_page_for_migration(mm, addr, current_node, 1833a49bd4d7SMichal Hocko &pagelist, flags & MPOL_MF_MOVE_ALL); 1834e0153fc2SYang Shi 1835d08221a0SWei Yang if (err > 0) { 1836e0153fc2SYang Shi /* The page is successfully queued for migration */ 1837e0153fc2SYang Shi continue; 1838e0153fc2SYang Shi } 18393140a227SBrice Goglin 1840d08221a0SWei Yang /* 1841d08221a0SWei Yang * If the page is already on the target node (!err), store the 1842d08221a0SWei Yang * node, otherwise, store the err. 1843d08221a0SWei Yang */ 1844d08221a0SWei Yang err = store_status(status, i, err ? : current_node, 1); 1845a49bd4d7SMichal Hocko if (err) 1846a49bd4d7SMichal Hocko goto out_flush; 18473140a227SBrice Goglin 18487ca8783aSWei Yang err = move_pages_and_store_status(mm, current_node, &pagelist, 18497ca8783aSWei Yang status, start, i, nr_pages); 1850a49bd4d7SMichal Hocko if (err) 1851a49bd4d7SMichal Hocko goto out; 1852a49bd4d7SMichal Hocko current_node = NUMA_NO_NODE; 18533140a227SBrice Goglin } 1854a49bd4d7SMichal Hocko out_flush: 1855a49bd4d7SMichal Hocko /* Make sure we do not overwrite the existing error */ 18567ca8783aSWei Yang err1 = move_pages_and_store_status(mm, current_node, &pagelist, 18577ca8783aSWei Yang status, start, i, nr_pages); 1858dfe9aa23SWei Yang if (err >= 0) 1859a49bd4d7SMichal Hocko err = err1; 18605e9a0f02SBrice Goglin out: 1861361a2a22SMinchan Kim lru_cache_enable(); 18625e9a0f02SBrice Goglin return err; 18635e9a0f02SBrice Goglin } 18645e9a0f02SBrice Goglin 18655e9a0f02SBrice Goglin /* 18662f007e74SBrice Goglin * Determine the nodes of an array of pages and store it in an array of status. 1867742755a1SChristoph Lameter */ 186880bba129SBrice Goglin static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, 186980bba129SBrice Goglin const void __user **pages, int *status) 1870742755a1SChristoph Lameter { 18712f007e74SBrice Goglin unsigned long i; 1872742755a1SChristoph Lameter 1873d8ed45c5SMichel Lespinasse mmap_read_lock(mm); 18742f007e74SBrice Goglin 18752f007e74SBrice Goglin for (i = 0; i < nr_pages; i++) { 187680bba129SBrice Goglin unsigned long addr = (unsigned long)(*pages); 18772f007e74SBrice Goglin struct vm_area_struct *vma; 18782f007e74SBrice Goglin struct page *page; 1879c095adbcSKOSAKI Motohiro int err = -EFAULT; 18802f007e74SBrice Goglin 1881059b8b48SLiam Howlett vma = vma_lookup(mm, addr); 1882059b8b48SLiam Howlett if (!vma) 1883742755a1SChristoph Lameter goto set_status; 1884742755a1SChristoph Lameter 1885d899844eSKirill A. Shutemov /* FOLL_DUMP to ignore special (like zero) pages */ 1886d899844eSKirill A. Shutemov page = follow_page(vma, addr, FOLL_DUMP); 188789f5b7daSLinus Torvalds 188889f5b7daSLinus Torvalds err = PTR_ERR(page); 188989f5b7daSLinus Torvalds if (IS_ERR(page)) 189089f5b7daSLinus Torvalds goto set_status; 189189f5b7daSLinus Torvalds 1892d899844eSKirill A. Shutemov err = page ? page_to_nid(page) : -ENOENT; 1893742755a1SChristoph Lameter set_status: 189480bba129SBrice Goglin *status = err; 189580bba129SBrice Goglin 189680bba129SBrice Goglin pages++; 189780bba129SBrice Goglin status++; 189880bba129SBrice Goglin } 189980bba129SBrice Goglin 1900d8ed45c5SMichel Lespinasse mmap_read_unlock(mm); 190180bba129SBrice Goglin } 190280bba129SBrice Goglin 1903*5b1b561bSArnd Bergmann static int get_compat_pages_array(const void __user *chunk_pages[], 1904*5b1b561bSArnd Bergmann const void __user * __user *pages, 1905*5b1b561bSArnd Bergmann unsigned long chunk_nr) 1906*5b1b561bSArnd Bergmann { 1907*5b1b561bSArnd Bergmann compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages; 1908*5b1b561bSArnd Bergmann compat_uptr_t p; 1909*5b1b561bSArnd Bergmann int i; 1910*5b1b561bSArnd Bergmann 1911*5b1b561bSArnd Bergmann for (i = 0; i < chunk_nr; i++) { 1912*5b1b561bSArnd Bergmann if (get_user(p, pages32 + i)) 1913*5b1b561bSArnd Bergmann return -EFAULT; 1914*5b1b561bSArnd Bergmann chunk_pages[i] = compat_ptr(p); 1915*5b1b561bSArnd Bergmann } 1916*5b1b561bSArnd Bergmann 1917*5b1b561bSArnd Bergmann return 0; 1918*5b1b561bSArnd Bergmann } 1919*5b1b561bSArnd Bergmann 192080bba129SBrice Goglin /* 192180bba129SBrice Goglin * Determine the nodes of a user array of pages and store it in 192280bba129SBrice Goglin * a user array of status. 192380bba129SBrice Goglin */ 192480bba129SBrice Goglin static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, 192580bba129SBrice Goglin const void __user * __user *pages, 192680bba129SBrice Goglin int __user *status) 192780bba129SBrice Goglin { 192880bba129SBrice Goglin #define DO_PAGES_STAT_CHUNK_NR 16 192980bba129SBrice Goglin const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; 193080bba129SBrice Goglin int chunk_status[DO_PAGES_STAT_CHUNK_NR]; 193180bba129SBrice Goglin 193287b8d1adSH. Peter Anvin while (nr_pages) { 193387b8d1adSH. Peter Anvin unsigned long chunk_nr; 193480bba129SBrice Goglin 193587b8d1adSH. Peter Anvin chunk_nr = nr_pages; 193687b8d1adSH. Peter Anvin if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) 193787b8d1adSH. Peter Anvin chunk_nr = DO_PAGES_STAT_CHUNK_NR; 193887b8d1adSH. Peter Anvin 1939*5b1b561bSArnd Bergmann if (in_compat_syscall()) { 1940*5b1b561bSArnd Bergmann if (get_compat_pages_array(chunk_pages, pages, 1941*5b1b561bSArnd Bergmann chunk_nr)) 194287b8d1adSH. Peter Anvin break; 1943*5b1b561bSArnd Bergmann } else { 1944*5b1b561bSArnd Bergmann if (copy_from_user(chunk_pages, pages, 1945*5b1b561bSArnd Bergmann chunk_nr * sizeof(*chunk_pages))) 1946*5b1b561bSArnd Bergmann break; 1947*5b1b561bSArnd Bergmann } 194880bba129SBrice Goglin 194980bba129SBrice Goglin do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); 195080bba129SBrice Goglin 195187b8d1adSH. Peter Anvin if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) 195287b8d1adSH. Peter Anvin break; 1953742755a1SChristoph Lameter 195487b8d1adSH. Peter Anvin pages += chunk_nr; 195587b8d1adSH. Peter Anvin status += chunk_nr; 195687b8d1adSH. Peter Anvin nr_pages -= chunk_nr; 195787b8d1adSH. Peter Anvin } 195887b8d1adSH. Peter Anvin return nr_pages ? -EFAULT : 0; 1959742755a1SChristoph Lameter } 1960742755a1SChristoph Lameter 19614dc200ceSMiaohe Lin static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes) 19624dc200ceSMiaohe Lin { 19634dc200ceSMiaohe Lin struct task_struct *task; 19644dc200ceSMiaohe Lin struct mm_struct *mm; 19654dc200ceSMiaohe Lin 19664dc200ceSMiaohe Lin /* 19674dc200ceSMiaohe Lin * There is no need to check if current process has the right to modify 19684dc200ceSMiaohe Lin * the specified process when they are same. 19694dc200ceSMiaohe Lin */ 19704dc200ceSMiaohe Lin if (!pid) { 19714dc200ceSMiaohe Lin mmget(current->mm); 19724dc200ceSMiaohe Lin *mem_nodes = cpuset_mems_allowed(current); 19734dc200ceSMiaohe Lin return current->mm; 19744dc200ceSMiaohe Lin } 19754dc200ceSMiaohe Lin 19764dc200ceSMiaohe Lin /* Find the mm_struct */ 19774dc200ceSMiaohe Lin rcu_read_lock(); 19784dc200ceSMiaohe Lin task = find_task_by_vpid(pid); 19794dc200ceSMiaohe Lin if (!task) { 19804dc200ceSMiaohe Lin rcu_read_unlock(); 19814dc200ceSMiaohe Lin return ERR_PTR(-ESRCH); 19824dc200ceSMiaohe Lin } 19834dc200ceSMiaohe Lin get_task_struct(task); 19844dc200ceSMiaohe Lin 19854dc200ceSMiaohe Lin /* 19864dc200ceSMiaohe Lin * Check if this process has the right to modify the specified 19874dc200ceSMiaohe Lin * process. Use the regular "ptrace_may_access()" checks. 19884dc200ceSMiaohe Lin */ 19894dc200ceSMiaohe Lin if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) { 19904dc200ceSMiaohe Lin rcu_read_unlock(); 19914dc200ceSMiaohe Lin mm = ERR_PTR(-EPERM); 19924dc200ceSMiaohe Lin goto out; 19934dc200ceSMiaohe Lin } 19944dc200ceSMiaohe Lin rcu_read_unlock(); 19954dc200ceSMiaohe Lin 19964dc200ceSMiaohe Lin mm = ERR_PTR(security_task_movememory(task)); 19974dc200ceSMiaohe Lin if (IS_ERR(mm)) 19984dc200ceSMiaohe Lin goto out; 19994dc200ceSMiaohe Lin *mem_nodes = cpuset_mems_allowed(task); 20004dc200ceSMiaohe Lin mm = get_task_mm(task); 20014dc200ceSMiaohe Lin out: 20024dc200ceSMiaohe Lin put_task_struct(task); 20034dc200ceSMiaohe Lin if (!mm) 20044dc200ceSMiaohe Lin mm = ERR_PTR(-EINVAL); 20054dc200ceSMiaohe Lin return mm; 20064dc200ceSMiaohe Lin } 20074dc200ceSMiaohe Lin 2008742755a1SChristoph Lameter /* 2009742755a1SChristoph Lameter * Move a list of pages in the address space of the currently executing 2010742755a1SChristoph Lameter * process. 2011742755a1SChristoph Lameter */ 20127addf443SDominik Brodowski static int kernel_move_pages(pid_t pid, unsigned long nr_pages, 20137addf443SDominik Brodowski const void __user * __user *pages, 20147addf443SDominik Brodowski const int __user *nodes, 20157addf443SDominik Brodowski int __user *status, int flags) 2016742755a1SChristoph Lameter { 2017742755a1SChristoph Lameter struct mm_struct *mm; 20185e9a0f02SBrice Goglin int err; 20193268c63eSChristoph Lameter nodemask_t task_nodes; 2020742755a1SChristoph Lameter 2021742755a1SChristoph Lameter /* Check flags */ 2022742755a1SChristoph Lameter if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) 2023742755a1SChristoph Lameter return -EINVAL; 2024742755a1SChristoph Lameter 2025742755a1SChristoph Lameter if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) 2026742755a1SChristoph Lameter return -EPERM; 2027742755a1SChristoph Lameter 20284dc200ceSMiaohe Lin mm = find_mm_struct(pid, &task_nodes); 20294dc200ceSMiaohe Lin if (IS_ERR(mm)) 20304dc200ceSMiaohe Lin return PTR_ERR(mm); 20316e8b09eaSSasha Levin 20323268c63eSChristoph Lameter if (nodes) 20333268c63eSChristoph Lameter err = do_pages_move(mm, task_nodes, nr_pages, pages, 20343268c63eSChristoph Lameter nodes, status, flags); 20353268c63eSChristoph Lameter else 20365e9a0f02SBrice Goglin err = do_pages_stat(mm, nr_pages, pages, status); 20373268c63eSChristoph Lameter 20383268c63eSChristoph Lameter mmput(mm); 20393268c63eSChristoph Lameter return err; 2040742755a1SChristoph Lameter } 2041742755a1SChristoph Lameter 20427addf443SDominik Brodowski SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, 20437addf443SDominik Brodowski const void __user * __user *, pages, 20447addf443SDominik Brodowski const int __user *, nodes, 20457addf443SDominik Brodowski int __user *, status, int, flags) 20467addf443SDominik Brodowski { 20477addf443SDominik Brodowski return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags); 20487addf443SDominik Brodowski } 20497addf443SDominik Brodowski 20507addf443SDominik Brodowski #ifdef CONFIG_COMPAT 20517addf443SDominik Brodowski COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages, 2052*5b1b561bSArnd Bergmann compat_uptr_t __user *, pages, 20537addf443SDominik Brodowski const int __user *, nodes, 20547addf443SDominik Brodowski int __user *, status, 20557addf443SDominik Brodowski int, flags) 20567addf443SDominik Brodowski { 2057*5b1b561bSArnd Bergmann return kernel_move_pages(pid, nr_pages, 2058*5b1b561bSArnd Bergmann (const void __user *__user *)pages, 2059*5b1b561bSArnd Bergmann nodes, status, flags); 20607addf443SDominik Brodowski } 20617addf443SDominik Brodowski #endif /* CONFIG_COMPAT */ 20627addf443SDominik Brodowski 20637039e1dbSPeter Zijlstra #ifdef CONFIG_NUMA_BALANCING 20647039e1dbSPeter Zijlstra /* 20657039e1dbSPeter Zijlstra * Returns true if this is a safe migration target node for misplaced NUMA 20667039e1dbSPeter Zijlstra * pages. Currently it only checks the watermarks which crude 20677039e1dbSPeter Zijlstra */ 20687039e1dbSPeter Zijlstra static bool migrate_balanced_pgdat(struct pglist_data *pgdat, 20693abef4e6SMel Gorman unsigned long nr_migrate_pages) 20707039e1dbSPeter Zijlstra { 20717039e1dbSPeter Zijlstra int z; 2072599d0c95SMel Gorman 20737039e1dbSPeter Zijlstra for (z = pgdat->nr_zones - 1; z >= 0; z--) { 20747039e1dbSPeter Zijlstra struct zone *zone = pgdat->node_zones + z; 20757039e1dbSPeter Zijlstra 20767039e1dbSPeter Zijlstra if (!populated_zone(zone)) 20777039e1dbSPeter Zijlstra continue; 20787039e1dbSPeter Zijlstra 20797039e1dbSPeter Zijlstra /* Avoid waking kswapd by allocating pages_to_migrate pages. */ 20807039e1dbSPeter Zijlstra if (!zone_watermark_ok(zone, 0, 20817039e1dbSPeter Zijlstra high_wmark_pages(zone) + 20827039e1dbSPeter Zijlstra nr_migrate_pages, 2083bfe9d006SHuang Ying ZONE_MOVABLE, 0)) 20847039e1dbSPeter Zijlstra continue; 20857039e1dbSPeter Zijlstra return true; 20867039e1dbSPeter Zijlstra } 20877039e1dbSPeter Zijlstra return false; 20887039e1dbSPeter Zijlstra } 20897039e1dbSPeter Zijlstra 20907039e1dbSPeter Zijlstra static struct page *alloc_misplaced_dst_page(struct page *page, 2091666feb21SMichal Hocko unsigned long data) 20927039e1dbSPeter Zijlstra { 20937039e1dbSPeter Zijlstra int nid = (int) data; 20947039e1dbSPeter Zijlstra struct page *newpage; 20957039e1dbSPeter Zijlstra 209696db800fSVlastimil Babka newpage = __alloc_pages_node(nid, 2097e97ca8e5SJohannes Weiner (GFP_HIGHUSER_MOVABLE | 2098e97ca8e5SJohannes Weiner __GFP_THISNODE | __GFP_NOMEMALLOC | 2099e97ca8e5SJohannes Weiner __GFP_NORETRY | __GFP_NOWARN) & 21008479eba7SMel Gorman ~__GFP_RECLAIM, 0); 2101bac0382cSHillf Danton 21027039e1dbSPeter Zijlstra return newpage; 21037039e1dbSPeter Zijlstra } 21047039e1dbSPeter Zijlstra 2105c5b5a3ddSYang Shi static struct page *alloc_misplaced_dst_page_thp(struct page *page, 2106c5b5a3ddSYang Shi unsigned long data) 2107c5b5a3ddSYang Shi { 2108c5b5a3ddSYang Shi int nid = (int) data; 2109c5b5a3ddSYang Shi struct page *newpage; 2110c5b5a3ddSYang Shi 2111c5b5a3ddSYang Shi newpage = alloc_pages_node(nid, (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), 2112c5b5a3ddSYang Shi HPAGE_PMD_ORDER); 2113c5b5a3ddSYang Shi if (!newpage) 2114c5b5a3ddSYang Shi goto out; 2115c5b5a3ddSYang Shi 2116c5b5a3ddSYang Shi prep_transhuge_page(newpage); 2117c5b5a3ddSYang Shi 2118c5b5a3ddSYang Shi out: 2119c5b5a3ddSYang Shi return newpage; 2120c5b5a3ddSYang Shi } 2121c5b5a3ddSYang Shi 21221c30e017SMel Gorman static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) 2123b32967ffSMel Gorman { 2124340ef390SHugh Dickins int page_lru; 21252b9b624fSBaolin Wang int nr_pages = thp_nr_pages(page); 2126b32967ffSMel Gorman 2127309381feSSasha Levin VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); 21283abef4e6SMel Gorman 2129662aeea7SYang Shi /* Do not migrate THP mapped by multiple processes */ 2130662aeea7SYang Shi if (PageTransHuge(page) && total_mapcount(page) > 1) 2131662aeea7SYang Shi return 0; 2132662aeea7SYang Shi 2133b32967ffSMel Gorman /* Avoid migrating to a node that is nearly full */ 21342b9b624fSBaolin Wang if (!migrate_balanced_pgdat(pgdat, nr_pages)) 2135340ef390SHugh Dickins return 0; 2136b32967ffSMel Gorman 2137340ef390SHugh Dickins if (isolate_lru_page(page)) 2138340ef390SHugh Dickins return 0; 2139340ef390SHugh Dickins 21409de4f22aSHuang Ying page_lru = page_is_file_lru(page); 2141599d0c95SMel Gorman mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, 21422b9b624fSBaolin Wang nr_pages); 2143b32967ffSMel Gorman 2144b32967ffSMel Gorman /* 2145340ef390SHugh Dickins * Isolating the page has taken another reference, so the 2146340ef390SHugh Dickins * caller's reference can be safely dropped without the page 2147340ef390SHugh Dickins * disappearing underneath us during migration. 2148b32967ffSMel Gorman */ 2149b32967ffSMel Gorman put_page(page); 2150340ef390SHugh Dickins return 1; 2151b32967ffSMel Gorman } 2152b32967ffSMel Gorman 2153a8f60772SMel Gorman /* 21547039e1dbSPeter Zijlstra * Attempt to migrate a misplaced page to the specified destination 21557039e1dbSPeter Zijlstra * node. Caller is expected to have an elevated reference count on 21567039e1dbSPeter Zijlstra * the page that will be dropped by this function before returning. 21577039e1dbSPeter Zijlstra */ 21581bc115d8SMel Gorman int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, 21591bc115d8SMel Gorman int node) 21607039e1dbSPeter Zijlstra { 2161a8f60772SMel Gorman pg_data_t *pgdat = NODE_DATA(node); 2162340ef390SHugh Dickins int isolated; 2163b32967ffSMel Gorman int nr_remaining; 21647039e1dbSPeter Zijlstra LIST_HEAD(migratepages); 2165c5b5a3ddSYang Shi new_page_t *new; 2166c5b5a3ddSYang Shi bool compound; 2167b5916c02SAneesh Kumar K.V int nr_pages = thp_nr_pages(page); 2168c5b5a3ddSYang Shi 2169c5b5a3ddSYang Shi /* 2170c5b5a3ddSYang Shi * PTE mapped THP or HugeTLB page can't reach here so the page could 2171c5b5a3ddSYang Shi * be either base page or THP. And it must be head page if it is 2172c5b5a3ddSYang Shi * THP. 2173c5b5a3ddSYang Shi */ 2174c5b5a3ddSYang Shi compound = PageTransHuge(page); 2175c5b5a3ddSYang Shi 2176c5b5a3ddSYang Shi if (compound) 2177c5b5a3ddSYang Shi new = alloc_misplaced_dst_page_thp; 2178c5b5a3ddSYang Shi else 2179c5b5a3ddSYang Shi new = alloc_misplaced_dst_page; 21807039e1dbSPeter Zijlstra 21817039e1dbSPeter Zijlstra /* 21821bc115d8SMel Gorman * Don't migrate file pages that are mapped in multiple processes 21831bc115d8SMel Gorman * with execute permissions as they are probably shared libraries. 21847039e1dbSPeter Zijlstra */ 21857ee820eeSMiaohe Lin if (page_mapcount(page) != 1 && page_is_file_lru(page) && 21867ee820eeSMiaohe Lin (vma->vm_flags & VM_EXEC)) 21877039e1dbSPeter Zijlstra goto out; 21887039e1dbSPeter Zijlstra 2189a8f60772SMel Gorman /* 219009a913a7SMel Gorman * Also do not migrate dirty pages as not all filesystems can move 219109a913a7SMel Gorman * dirty pages in MIGRATE_ASYNC mode which is a waste of cycles. 219209a913a7SMel Gorman */ 21939de4f22aSHuang Ying if (page_is_file_lru(page) && PageDirty(page)) 219409a913a7SMel Gorman goto out; 219509a913a7SMel Gorman 2196b32967ffSMel Gorman isolated = numamigrate_isolate_page(pgdat, page); 2197b32967ffSMel Gorman if (!isolated) 21987039e1dbSPeter Zijlstra goto out; 21997039e1dbSPeter Zijlstra 22007039e1dbSPeter Zijlstra list_add(&page->lru, &migratepages); 2201c5b5a3ddSYang Shi nr_remaining = migrate_pages(&migratepages, *new, NULL, node, 22025ac95884SYang Shi MIGRATE_ASYNC, MR_NUMA_MISPLACED, NULL); 22037039e1dbSPeter Zijlstra if (nr_remaining) { 220459c82b70SJoonsoo Kim if (!list_empty(&migratepages)) { 220559c82b70SJoonsoo Kim list_del(&page->lru); 2206c5fc5c3aSYang Shi mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + 2207c5fc5c3aSYang Shi page_is_file_lru(page), -nr_pages); 220859c82b70SJoonsoo Kim putback_lru_page(page); 220959c82b70SJoonsoo Kim } 22107039e1dbSPeter Zijlstra isolated = 0; 221103c5a6e1SMel Gorman } else 2212c5fc5c3aSYang Shi count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_pages); 22137039e1dbSPeter Zijlstra BUG_ON(!list_empty(&migratepages)); 22147039e1dbSPeter Zijlstra return isolated; 2215340ef390SHugh Dickins 2216340ef390SHugh Dickins out: 2217340ef390SHugh Dickins put_page(page); 2218340ef390SHugh Dickins return 0; 22197039e1dbSPeter Zijlstra } 2220220018d3SMel Gorman #endif /* CONFIG_NUMA_BALANCING */ 22217039e1dbSPeter Zijlstra #endif /* CONFIG_NUMA */ 22228763cb45SJérôme Glisse 22239b2ed9cbSChristoph Hellwig #ifdef CONFIG_DEVICE_PRIVATE 22248315ada7SJérôme Glisse static int migrate_vma_collect_skip(unsigned long start, 22258315ada7SJérôme Glisse unsigned long end, 22268315ada7SJérôme Glisse struct mm_walk *walk) 22278315ada7SJérôme Glisse { 22288315ada7SJérôme Glisse struct migrate_vma *migrate = walk->private; 22298315ada7SJérôme Glisse unsigned long addr; 22308315ada7SJérôme Glisse 2231872ea707SRalph Campbell for (addr = start; addr < end; addr += PAGE_SIZE) { 22328763cb45SJérôme Glisse migrate->dst[migrate->npages] = 0; 22338763cb45SJérôme Glisse migrate->src[migrate->npages++] = 0; 22348763cb45SJérôme Glisse } 22358763cb45SJérôme Glisse 22368763cb45SJérôme Glisse return 0; 22378763cb45SJérôme Glisse } 22388763cb45SJérôme Glisse 2239843e1be1SMiaohe Lin static int migrate_vma_collect_hole(unsigned long start, 2240843e1be1SMiaohe Lin unsigned long end, 2241843e1be1SMiaohe Lin __always_unused int depth, 2242843e1be1SMiaohe Lin struct mm_walk *walk) 2243843e1be1SMiaohe Lin { 2244843e1be1SMiaohe Lin struct migrate_vma *migrate = walk->private; 2245843e1be1SMiaohe Lin unsigned long addr; 2246843e1be1SMiaohe Lin 2247843e1be1SMiaohe Lin /* Only allow populating anonymous memory. */ 2248843e1be1SMiaohe Lin if (!vma_is_anonymous(walk->vma)) 2249843e1be1SMiaohe Lin return migrate_vma_collect_skip(start, end, walk); 2250843e1be1SMiaohe Lin 2251843e1be1SMiaohe Lin for (addr = start; addr < end; addr += PAGE_SIZE) { 2252843e1be1SMiaohe Lin migrate->src[migrate->npages] = MIGRATE_PFN_MIGRATE; 2253843e1be1SMiaohe Lin migrate->dst[migrate->npages] = 0; 2254843e1be1SMiaohe Lin migrate->npages++; 2255843e1be1SMiaohe Lin migrate->cpages++; 2256843e1be1SMiaohe Lin } 2257843e1be1SMiaohe Lin 2258843e1be1SMiaohe Lin return 0; 2259843e1be1SMiaohe Lin } 2260843e1be1SMiaohe Lin 22618763cb45SJérôme Glisse static int migrate_vma_collect_pmd(pmd_t *pmdp, 22628763cb45SJérôme Glisse unsigned long start, 22638763cb45SJérôme Glisse unsigned long end, 22648763cb45SJérôme Glisse struct mm_walk *walk) 22658763cb45SJérôme Glisse { 22668763cb45SJérôme Glisse struct migrate_vma *migrate = walk->private; 22678763cb45SJérôme Glisse struct vm_area_struct *vma = walk->vma; 22688763cb45SJérôme Glisse struct mm_struct *mm = vma->vm_mm; 22698c3328f1SJérôme Glisse unsigned long addr = start, unmapped = 0; 22708763cb45SJérôme Glisse spinlock_t *ptl; 22718763cb45SJérôme Glisse pte_t *ptep; 22728763cb45SJérôme Glisse 22738763cb45SJérôme Glisse again: 22748763cb45SJérôme Glisse if (pmd_none(*pmdp)) 2275b7a16c7aSSteven Price return migrate_vma_collect_hole(start, end, -1, walk); 22768763cb45SJérôme Glisse 22778763cb45SJérôme Glisse if (pmd_trans_huge(*pmdp)) { 22788763cb45SJérôme Glisse struct page *page; 22798763cb45SJérôme Glisse 22808763cb45SJérôme Glisse ptl = pmd_lock(mm, pmdp); 22818763cb45SJérôme Glisse if (unlikely(!pmd_trans_huge(*pmdp))) { 22828763cb45SJérôme Glisse spin_unlock(ptl); 22838763cb45SJérôme Glisse goto again; 22848763cb45SJérôme Glisse } 22858763cb45SJérôme Glisse 22868763cb45SJérôme Glisse page = pmd_page(*pmdp); 22878763cb45SJérôme Glisse if (is_huge_zero_page(page)) { 22888763cb45SJérôme Glisse spin_unlock(ptl); 22898763cb45SJérôme Glisse split_huge_pmd(vma, pmdp, addr); 22908763cb45SJérôme Glisse if (pmd_trans_unstable(pmdp)) 22918315ada7SJérôme Glisse return migrate_vma_collect_skip(start, end, 22928763cb45SJérôme Glisse walk); 22938763cb45SJérôme Glisse } else { 22948763cb45SJérôme Glisse int ret; 22958763cb45SJérôme Glisse 22968763cb45SJérôme Glisse get_page(page); 22978763cb45SJérôme Glisse spin_unlock(ptl); 22988763cb45SJérôme Glisse if (unlikely(!trylock_page(page))) 22998315ada7SJérôme Glisse return migrate_vma_collect_skip(start, end, 23008763cb45SJérôme Glisse walk); 23018763cb45SJérôme Glisse ret = split_huge_page(page); 23028763cb45SJérôme Glisse unlock_page(page); 23038763cb45SJérôme Glisse put_page(page); 23048315ada7SJérôme Glisse if (ret) 23058315ada7SJérôme Glisse return migrate_vma_collect_skip(start, end, 23068315ada7SJérôme Glisse walk); 23078315ada7SJérôme Glisse if (pmd_none(*pmdp)) 2308b7a16c7aSSteven Price return migrate_vma_collect_hole(start, end, -1, 23098763cb45SJérôme Glisse walk); 23108763cb45SJérôme Glisse } 23118763cb45SJérôme Glisse } 23128763cb45SJérôme Glisse 23138763cb45SJérôme Glisse if (unlikely(pmd_bad(*pmdp))) 23148315ada7SJérôme Glisse return migrate_vma_collect_skip(start, end, walk); 23158763cb45SJérôme Glisse 23168763cb45SJérôme Glisse ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); 23178c3328f1SJérôme Glisse arch_enter_lazy_mmu_mode(); 23188c3328f1SJérôme Glisse 23198763cb45SJérôme Glisse for (; addr < end; addr += PAGE_SIZE, ptep++) { 2320800bb1c8SChristoph Hellwig unsigned long mpfn = 0, pfn; 23218763cb45SJérôme Glisse struct page *page; 23228c3328f1SJérôme Glisse swp_entry_t entry; 23238763cb45SJérôme Glisse pte_t pte; 23248763cb45SJérôme Glisse 23258763cb45SJérôme Glisse pte = *ptep; 23268763cb45SJérôme Glisse 2327a5430ddaSJérôme Glisse if (pte_none(pte)) { 23280744f280SRalph Campbell if (vma_is_anonymous(vma)) { 23298315ada7SJérôme Glisse mpfn = MIGRATE_PFN_MIGRATE; 23308315ada7SJérôme Glisse migrate->cpages++; 23310744f280SRalph Campbell } 23328763cb45SJérôme Glisse goto next; 23338763cb45SJérôme Glisse } 23348763cb45SJérôme Glisse 2335a5430ddaSJérôme Glisse if (!pte_present(pte)) { 2336a5430ddaSJérôme Glisse /* 2337a5430ddaSJérôme Glisse * Only care about unaddressable device page special 2338a5430ddaSJérôme Glisse * page table entry. Other special swap entries are not 2339a5430ddaSJérôme Glisse * migratable, and we ignore regular swapped page. 2340a5430ddaSJérôme Glisse */ 2341a5430ddaSJérôme Glisse entry = pte_to_swp_entry(pte); 2342a5430ddaSJérôme Glisse if (!is_device_private_entry(entry)) 2343a5430ddaSJérôme Glisse goto next; 2344a5430ddaSJérôme Glisse 2345af5cdaf8SAlistair Popple page = pfn_swap_entry_to_page(entry); 23465143192cSRalph Campbell if (!(migrate->flags & 23475143192cSRalph Campbell MIGRATE_VMA_SELECT_DEVICE_PRIVATE) || 23485143192cSRalph Campbell page->pgmap->owner != migrate->pgmap_owner) 2349800bb1c8SChristoph Hellwig goto next; 2350800bb1c8SChristoph Hellwig 2351a5430ddaSJérôme Glisse mpfn = migrate_pfn(page_to_pfn(page)) | 235206d462beSChristoph Hellwig MIGRATE_PFN_MIGRATE; 23534dd845b5SAlistair Popple if (is_writable_device_private_entry(entry)) 2354a5430ddaSJérôme Glisse mpfn |= MIGRATE_PFN_WRITE; 2355a5430ddaSJérôme Glisse } else { 23565143192cSRalph Campbell if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) 2357800bb1c8SChristoph Hellwig goto next; 2358276f756dSPingfan Liu pfn = pte_pfn(pte); 23598315ada7SJérôme Glisse if (is_zero_pfn(pfn)) { 23608315ada7SJérôme Glisse mpfn = MIGRATE_PFN_MIGRATE; 23618315ada7SJérôme Glisse migrate->cpages++; 23628315ada7SJérôme Glisse goto next; 23638315ada7SJérôme Glisse } 236425b2995aSChristoph Hellwig page = vm_normal_page(migrate->vma, addr, pte); 2365a5430ddaSJérôme Glisse mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; 2366a5430ddaSJérôme Glisse mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; 2367a5430ddaSJérôme Glisse } 2368a5430ddaSJérôme Glisse 2369a5430ddaSJérôme Glisse /* FIXME support THP */ 23708763cb45SJérôme Glisse if (!page || !page->mapping || PageTransCompound(page)) { 2371276f756dSPingfan Liu mpfn = 0; 23728763cb45SJérôme Glisse goto next; 23738763cb45SJérôme Glisse } 23748763cb45SJérôme Glisse 23758763cb45SJérôme Glisse /* 23768763cb45SJérôme Glisse * By getting a reference on the page we pin it and that blocks 23778763cb45SJérôme Glisse * any kind of migration. Side effect is that it "freezes" the 23788763cb45SJérôme Glisse * pte. 23798763cb45SJérôme Glisse * 23808763cb45SJérôme Glisse * We drop this reference after isolating the page from the lru 23818763cb45SJérôme Glisse * for non device page (device page are not on the lru and thus 23828763cb45SJérôme Glisse * can't be dropped from it). 23838763cb45SJérôme Glisse */ 23848763cb45SJérôme Glisse get_page(page); 23858763cb45SJérôme Glisse migrate->cpages++; 23868763cb45SJérôme Glisse 23878c3328f1SJérôme Glisse /* 23888c3328f1SJérôme Glisse * Optimize for the common case where page is only mapped once 23898c3328f1SJérôme Glisse * in one process. If we can lock the page, then we can safely 23908c3328f1SJérôme Glisse * set up a special migration page table entry now. 23918c3328f1SJérôme Glisse */ 23928c3328f1SJérôme Glisse if (trylock_page(page)) { 23938c3328f1SJérôme Glisse pte_t swp_pte; 23948c3328f1SJérôme Glisse 23958c3328f1SJérôme Glisse mpfn |= MIGRATE_PFN_LOCKED; 23968c3328f1SJérôme Glisse ptep_get_and_clear(mm, addr, ptep); 23978c3328f1SJérôme Glisse 23988c3328f1SJérôme Glisse /* Setup special migration page table entry */ 23994dd845b5SAlistair Popple if (mpfn & MIGRATE_PFN_WRITE) 24004dd845b5SAlistair Popple entry = make_writable_migration_entry( 24014dd845b5SAlistair Popple page_to_pfn(page)); 24024dd845b5SAlistair Popple else 24034dd845b5SAlistair Popple entry = make_readable_migration_entry( 24044dd845b5SAlistair Popple page_to_pfn(page)); 24058c3328f1SJérôme Glisse swp_pte = swp_entry_to_pte(entry); 2406ad7df764SAlistair Popple if (pte_present(pte)) { 24078c3328f1SJérôme Glisse if (pte_soft_dirty(pte)) 24088c3328f1SJérôme Glisse swp_pte = pte_swp_mksoft_dirty(swp_pte); 2409f45ec5ffSPeter Xu if (pte_uffd_wp(pte)) 2410f45ec5ffSPeter Xu swp_pte = pte_swp_mkuffd_wp(swp_pte); 2411ad7df764SAlistair Popple } else { 2412ad7df764SAlistair Popple if (pte_swp_soft_dirty(pte)) 2413ad7df764SAlistair Popple swp_pte = pte_swp_mksoft_dirty(swp_pte); 2414ad7df764SAlistair Popple if (pte_swp_uffd_wp(pte)) 2415ad7df764SAlistair Popple swp_pte = pte_swp_mkuffd_wp(swp_pte); 2416ad7df764SAlistair Popple } 24178c3328f1SJérôme Glisse set_pte_at(mm, addr, ptep, swp_pte); 24188c3328f1SJérôme Glisse 24198c3328f1SJérôme Glisse /* 24208c3328f1SJérôme Glisse * This is like regular unmap: we remove the rmap and 24218c3328f1SJérôme Glisse * drop page refcount. Page won't be freed, as we took 24228c3328f1SJérôme Glisse * a reference just above. 24238c3328f1SJérôme Glisse */ 24248c3328f1SJérôme Glisse page_remove_rmap(page, false); 24258c3328f1SJérôme Glisse put_page(page); 2426a5430ddaSJérôme Glisse 2427a5430ddaSJérôme Glisse if (pte_present(pte)) 24288c3328f1SJérôme Glisse unmapped++; 24298c3328f1SJérôme Glisse } 24308c3328f1SJérôme Glisse 24318763cb45SJérôme Glisse next: 2432a5430ddaSJérôme Glisse migrate->dst[migrate->npages] = 0; 24338763cb45SJérôme Glisse migrate->src[migrate->npages++] = mpfn; 24348763cb45SJérôme Glisse } 24358c3328f1SJérôme Glisse arch_leave_lazy_mmu_mode(); 24368763cb45SJérôme Glisse pte_unmap_unlock(ptep - 1, ptl); 24378763cb45SJérôme Glisse 24388c3328f1SJérôme Glisse /* Only flush the TLB if we actually modified any entries */ 24398c3328f1SJérôme Glisse if (unmapped) 24408c3328f1SJérôme Glisse flush_tlb_range(walk->vma, start, end); 24418c3328f1SJérôme Glisse 24428763cb45SJérôme Glisse return 0; 24438763cb45SJérôme Glisse } 24448763cb45SJérôme Glisse 24457b86ac33SChristoph Hellwig static const struct mm_walk_ops migrate_vma_walk_ops = { 24467b86ac33SChristoph Hellwig .pmd_entry = migrate_vma_collect_pmd, 24477b86ac33SChristoph Hellwig .pte_hole = migrate_vma_collect_hole, 24487b86ac33SChristoph Hellwig }; 24497b86ac33SChristoph Hellwig 24508763cb45SJérôme Glisse /* 24518763cb45SJérôme Glisse * migrate_vma_collect() - collect pages over a range of virtual addresses 24528763cb45SJérôme Glisse * @migrate: migrate struct containing all migration information 24538763cb45SJérôme Glisse * 24548763cb45SJérôme Glisse * This will walk the CPU page table. For each virtual address backed by a 24558763cb45SJérôme Glisse * valid page, it updates the src array and takes a reference on the page, in 24568763cb45SJérôme Glisse * order to pin the page until we lock it and unmap it. 24578763cb45SJérôme Glisse */ 24588763cb45SJérôme Glisse static void migrate_vma_collect(struct migrate_vma *migrate) 24598763cb45SJérôme Glisse { 2460ac46d4f3SJérôme Glisse struct mmu_notifier_range range; 24618763cb45SJérôme Glisse 2462998427b3SRalph Campbell /* 2463998427b3SRalph Campbell * Note that the pgmap_owner is passed to the mmu notifier callback so 2464998427b3SRalph Campbell * that the registered device driver can skip invalidating device 2465998427b3SRalph Campbell * private page mappings that won't be migrated. 2466998427b3SRalph Campbell */ 24676b49bf6dSAlistair Popple mmu_notifier_range_init_owner(&range, MMU_NOTIFY_MIGRATE, 0, 24686b49bf6dSAlistair Popple migrate->vma, migrate->vma->vm_mm, migrate->start, migrate->end, 2469c1a06df6SRalph Campbell migrate->pgmap_owner); 2470ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_start(&range); 24718763cb45SJérôme Glisse 24727b86ac33SChristoph Hellwig walk_page_range(migrate->vma->vm_mm, migrate->start, migrate->end, 24737b86ac33SChristoph Hellwig &migrate_vma_walk_ops, migrate); 24747b86ac33SChristoph Hellwig 24757b86ac33SChristoph Hellwig mmu_notifier_invalidate_range_end(&range); 24768763cb45SJérôme Glisse migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT); 24778763cb45SJérôme Glisse } 24788763cb45SJérôme Glisse 24798763cb45SJérôme Glisse /* 24808763cb45SJérôme Glisse * migrate_vma_check_page() - check if page is pinned or not 24818763cb45SJérôme Glisse * @page: struct page to check 24828763cb45SJérôme Glisse * 24838763cb45SJérôme Glisse * Pinned pages cannot be migrated. This is the same test as in 24848763cb45SJérôme Glisse * migrate_page_move_mapping(), except that here we allow migration of a 24858763cb45SJérôme Glisse * ZONE_DEVICE page. 24868763cb45SJérôme Glisse */ 24878763cb45SJérôme Glisse static bool migrate_vma_check_page(struct page *page) 24888763cb45SJérôme Glisse { 24898763cb45SJérôme Glisse /* 24908763cb45SJérôme Glisse * One extra ref because caller holds an extra reference, either from 24918763cb45SJérôme Glisse * isolate_lru_page() for a regular page, or migrate_vma_collect() for 24928763cb45SJérôme Glisse * a device page. 24938763cb45SJérôme Glisse */ 24948763cb45SJérôme Glisse int extra = 1; 24958763cb45SJérôme Glisse 24968763cb45SJérôme Glisse /* 24978763cb45SJérôme Glisse * FIXME support THP (transparent huge page), it is bit more complex to 24988763cb45SJérôme Glisse * check them than regular pages, because they can be mapped with a pmd 24998763cb45SJérôme Glisse * or with a pte (split pte mapping). 25008763cb45SJérôme Glisse */ 25018763cb45SJérôme Glisse if (PageCompound(page)) 25028763cb45SJérôme Glisse return false; 25038763cb45SJérôme Glisse 2504a5430ddaSJérôme Glisse /* Page from ZONE_DEVICE have one extra reference */ 2505a5430ddaSJérôme Glisse if (is_zone_device_page(page)) { 2506a5430ddaSJérôme Glisse /* 2507a5430ddaSJérôme Glisse * Private page can never be pin as they have no valid pte and 2508a5430ddaSJérôme Glisse * GUP will fail for those. Yet if there is a pending migration 2509a5430ddaSJérôme Glisse * a thread might try to wait on the pte migration entry and 2510a5430ddaSJérôme Glisse * will bump the page reference count. Sadly there is no way to 2511a5430ddaSJérôme Glisse * differentiate a regular pin from migration wait. Hence to 2512a5430ddaSJérôme Glisse * avoid 2 racing thread trying to migrate back to CPU to enter 25138958b249SHaitao Shi * infinite loop (one stopping migration because the other is 2514a5430ddaSJérôme Glisse * waiting on pte migration entry). We always return true here. 2515a5430ddaSJérôme Glisse * 2516a5430ddaSJérôme Glisse * FIXME proper solution is to rework migration_entry_wait() so 2517a5430ddaSJérôme Glisse * it does not need to take a reference on page. 2518a5430ddaSJérôme Glisse */ 251925b2995aSChristoph Hellwig return is_device_private_page(page); 2520a5430ddaSJérôme Glisse } 2521a5430ddaSJérôme Glisse 2522df6ad698SJérôme Glisse /* For file back page */ 2523df6ad698SJérôme Glisse if (page_mapping(page)) 2524df6ad698SJérôme Glisse extra += 1 + page_has_private(page); 2525df6ad698SJérôme Glisse 25268763cb45SJérôme Glisse if ((page_count(page) - extra) > page_mapcount(page)) 25278763cb45SJérôme Glisse return false; 25288763cb45SJérôme Glisse 25298763cb45SJérôme Glisse return true; 25308763cb45SJérôme Glisse } 25318763cb45SJérôme Glisse 25328763cb45SJérôme Glisse /* 25338763cb45SJérôme Glisse * migrate_vma_prepare() - lock pages and isolate them from the lru 25348763cb45SJérôme Glisse * @migrate: migrate struct containing all migration information 25358763cb45SJérôme Glisse * 25368763cb45SJérôme Glisse * This locks pages that have been collected by migrate_vma_collect(). Once each 25378763cb45SJérôme Glisse * page is locked it is isolated from the lru (for non-device pages). Finally, 25388763cb45SJérôme Glisse * the ref taken by migrate_vma_collect() is dropped, as locked pages cannot be 25398763cb45SJérôme Glisse * migrated by concurrent kernel threads. 25408763cb45SJérôme Glisse */ 25418763cb45SJérôme Glisse static void migrate_vma_prepare(struct migrate_vma *migrate) 25428763cb45SJérôme Glisse { 25438763cb45SJérôme Glisse const unsigned long npages = migrate->npages; 25448c3328f1SJérôme Glisse const unsigned long start = migrate->start; 25458c3328f1SJérôme Glisse unsigned long addr, i, restore = 0; 25468763cb45SJérôme Glisse bool allow_drain = true; 25478763cb45SJérôme Glisse 25488763cb45SJérôme Glisse lru_add_drain(); 25498763cb45SJérôme Glisse 25508763cb45SJérôme Glisse for (i = 0; (i < npages) && migrate->cpages; i++) { 25518763cb45SJérôme Glisse struct page *page = migrate_pfn_to_page(migrate->src[i]); 25528c3328f1SJérôme Glisse bool remap = true; 25538763cb45SJérôme Glisse 25548763cb45SJérôme Glisse if (!page) 25558763cb45SJérôme Glisse continue; 25568763cb45SJérôme Glisse 25578c3328f1SJérôme Glisse if (!(migrate->src[i] & MIGRATE_PFN_LOCKED)) { 25588763cb45SJérôme Glisse /* 25598763cb45SJérôme Glisse * Because we are migrating several pages there can be 25608763cb45SJérôme Glisse * a deadlock between 2 concurrent migration where each 25618763cb45SJérôme Glisse * are waiting on each other page lock. 25628763cb45SJérôme Glisse * 25638763cb45SJérôme Glisse * Make migrate_vma() a best effort thing and backoff 25648763cb45SJérôme Glisse * for any page we can not lock right away. 25658763cb45SJérôme Glisse */ 25668763cb45SJérôme Glisse if (!trylock_page(page)) { 25678763cb45SJérôme Glisse migrate->src[i] = 0; 25688763cb45SJérôme Glisse migrate->cpages--; 25698763cb45SJérôme Glisse put_page(page); 25708763cb45SJérôme Glisse continue; 25718763cb45SJérôme Glisse } 25728c3328f1SJérôme Glisse remap = false; 25738763cb45SJérôme Glisse migrate->src[i] |= MIGRATE_PFN_LOCKED; 25748c3328f1SJérôme Glisse } 25758763cb45SJérôme Glisse 2576a5430ddaSJérôme Glisse /* ZONE_DEVICE pages are not on LRU */ 2577a5430ddaSJérôme Glisse if (!is_zone_device_page(page)) { 25788763cb45SJérôme Glisse if (!PageLRU(page) && allow_drain) { 25798763cb45SJérôme Glisse /* Drain CPU's pagevec */ 25808763cb45SJérôme Glisse lru_add_drain_all(); 25818763cb45SJérôme Glisse allow_drain = false; 25828763cb45SJérôme Glisse } 25838763cb45SJérôme Glisse 25848763cb45SJérôme Glisse if (isolate_lru_page(page)) { 25858c3328f1SJérôme Glisse if (remap) { 25868c3328f1SJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 25878c3328f1SJérôme Glisse migrate->cpages--; 25888c3328f1SJérôme Glisse restore++; 25898c3328f1SJérôme Glisse } else { 25908763cb45SJérôme Glisse migrate->src[i] = 0; 25918763cb45SJérôme Glisse unlock_page(page); 25928763cb45SJérôme Glisse migrate->cpages--; 25938763cb45SJérôme Glisse put_page(page); 25948c3328f1SJérôme Glisse } 25958763cb45SJérôme Glisse continue; 25968763cb45SJérôme Glisse } 25978763cb45SJérôme Glisse 2598a5430ddaSJérôme Glisse /* Drop the reference we took in collect */ 2599a5430ddaSJérôme Glisse put_page(page); 2600a5430ddaSJérôme Glisse } 2601a5430ddaSJérôme Glisse 26028763cb45SJérôme Glisse if (!migrate_vma_check_page(page)) { 26038c3328f1SJérôme Glisse if (remap) { 26048c3328f1SJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 26058c3328f1SJérôme Glisse migrate->cpages--; 26068c3328f1SJérôme Glisse restore++; 26078c3328f1SJérôme Glisse 2608a5430ddaSJérôme Glisse if (!is_zone_device_page(page)) { 26098c3328f1SJérôme Glisse get_page(page); 26108c3328f1SJérôme Glisse putback_lru_page(page); 2611a5430ddaSJérôme Glisse } 26128c3328f1SJérôme Glisse } else { 26138763cb45SJérôme Glisse migrate->src[i] = 0; 26148763cb45SJérôme Glisse unlock_page(page); 26158763cb45SJérôme Glisse migrate->cpages--; 26168763cb45SJérôme Glisse 2617a5430ddaSJérôme Glisse if (!is_zone_device_page(page)) 26188763cb45SJérôme Glisse putback_lru_page(page); 2619a5430ddaSJérôme Glisse else 2620a5430ddaSJérôme Glisse put_page(page); 26218763cb45SJérôme Glisse } 26228763cb45SJérôme Glisse } 26238763cb45SJérôme Glisse } 26248763cb45SJérôme Glisse 26258c3328f1SJérôme Glisse for (i = 0, addr = start; i < npages && restore; i++, addr += PAGE_SIZE) { 26268c3328f1SJérôme Glisse struct page *page = migrate_pfn_to_page(migrate->src[i]); 26278c3328f1SJérôme Glisse 26288c3328f1SJérôme Glisse if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) 26298c3328f1SJérôme Glisse continue; 26308c3328f1SJérôme Glisse 26318c3328f1SJérôme Glisse remove_migration_pte(page, migrate->vma, addr, page); 26328c3328f1SJérôme Glisse 26338c3328f1SJérôme Glisse migrate->src[i] = 0; 26348c3328f1SJérôme Glisse unlock_page(page); 26358c3328f1SJérôme Glisse put_page(page); 26368c3328f1SJérôme Glisse restore--; 26378c3328f1SJérôme Glisse } 26388c3328f1SJérôme Glisse } 26398c3328f1SJérôme Glisse 26408763cb45SJérôme Glisse /* 26418763cb45SJérôme Glisse * migrate_vma_unmap() - replace page mapping with special migration pte entry 26428763cb45SJérôme Glisse * @migrate: migrate struct containing all migration information 26438763cb45SJérôme Glisse * 26448763cb45SJérôme Glisse * Replace page mapping (CPU page table pte) with a special migration pte entry 26458763cb45SJérôme Glisse * and check again if it has been pinned. Pinned pages are restored because we 26468763cb45SJérôme Glisse * cannot migrate them. 26478763cb45SJérôme Glisse * 26488763cb45SJérôme Glisse * This is the last step before we call the device driver callback to allocate 26498763cb45SJérôme Glisse * destination memory and copy contents of original page over to new page. 26508763cb45SJérôme Glisse */ 26518763cb45SJérôme Glisse static void migrate_vma_unmap(struct migrate_vma *migrate) 26528763cb45SJérôme Glisse { 26538763cb45SJérôme Glisse const unsigned long npages = migrate->npages; 26548763cb45SJérôme Glisse const unsigned long start = migrate->start; 26558763cb45SJérôme Glisse unsigned long addr, i, restore = 0; 26568763cb45SJérôme Glisse 26578763cb45SJérôme Glisse for (i = 0; i < npages; i++) { 26588763cb45SJérôme Glisse struct page *page = migrate_pfn_to_page(migrate->src[i]); 26598763cb45SJérôme Glisse 26608763cb45SJérôme Glisse if (!page || !(migrate->src[i] & MIGRATE_PFN_MIGRATE)) 26618763cb45SJérôme Glisse continue; 26628763cb45SJérôme Glisse 26638c3328f1SJérôme Glisse if (page_mapped(page)) { 2664a98a2f0cSAlistair Popple try_to_migrate(page, 0); 26658c3328f1SJérôme Glisse if (page_mapped(page)) 26668c3328f1SJérôme Glisse goto restore; 26678c3328f1SJérôme Glisse } 26688c3328f1SJérôme Glisse 26698c3328f1SJérôme Glisse if (migrate_vma_check_page(page)) 26708c3328f1SJérôme Glisse continue; 26718c3328f1SJérôme Glisse 26728c3328f1SJérôme Glisse restore: 26738763cb45SJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 26748763cb45SJérôme Glisse migrate->cpages--; 26758763cb45SJérôme Glisse restore++; 26768763cb45SJérôme Glisse } 26778763cb45SJérôme Glisse 26788763cb45SJérôme Glisse for (addr = start, i = 0; i < npages && restore; addr += PAGE_SIZE, i++) { 26798763cb45SJérôme Glisse struct page *page = migrate_pfn_to_page(migrate->src[i]); 26808763cb45SJérôme Glisse 26818763cb45SJérôme Glisse if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE)) 26828763cb45SJérôme Glisse continue; 26838763cb45SJérôme Glisse 26848763cb45SJérôme Glisse remove_migration_ptes(page, page, false); 26858763cb45SJérôme Glisse 26868763cb45SJérôme Glisse migrate->src[i] = 0; 26878763cb45SJérôme Glisse unlock_page(page); 26888763cb45SJérôme Glisse restore--; 26898763cb45SJérôme Glisse 2690a5430ddaSJérôme Glisse if (is_zone_device_page(page)) 2691a5430ddaSJérôme Glisse put_page(page); 2692a5430ddaSJérôme Glisse else 26938763cb45SJérôme Glisse putback_lru_page(page); 26948763cb45SJérôme Glisse } 26958763cb45SJérôme Glisse } 26968763cb45SJérôme Glisse 2697a7d1f22bSChristoph Hellwig /** 2698a7d1f22bSChristoph Hellwig * migrate_vma_setup() - prepare to migrate a range of memory 2699eaf444deSRandy Dunlap * @args: contains the vma, start, and pfns arrays for the migration 2700a7d1f22bSChristoph Hellwig * 2701a7d1f22bSChristoph Hellwig * Returns: negative errno on failures, 0 when 0 or more pages were migrated 2702a7d1f22bSChristoph Hellwig * without an error. 2703a7d1f22bSChristoph Hellwig * 2704a7d1f22bSChristoph Hellwig * Prepare to migrate a range of memory virtual address range by collecting all 2705a7d1f22bSChristoph Hellwig * the pages backing each virtual address in the range, saving them inside the 2706a7d1f22bSChristoph Hellwig * src array. Then lock those pages and unmap them. Once the pages are locked 2707a7d1f22bSChristoph Hellwig * and unmapped, check whether each page is pinned or not. Pages that aren't 2708a7d1f22bSChristoph Hellwig * pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) in the 2709a7d1f22bSChristoph Hellwig * corresponding src array entry. Then restores any pages that are pinned, by 2710a7d1f22bSChristoph Hellwig * remapping and unlocking those pages. 2711a7d1f22bSChristoph Hellwig * 2712a7d1f22bSChristoph Hellwig * The caller should then allocate destination memory and copy source memory to 2713a7d1f22bSChristoph Hellwig * it for all those entries (ie with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE 2714a7d1f22bSChristoph Hellwig * flag set). Once these are allocated and copied, the caller must update each 2715a7d1f22bSChristoph Hellwig * corresponding entry in the dst array with the pfn value of the destination 2716a7d1f22bSChristoph Hellwig * page and with the MIGRATE_PFN_VALID and MIGRATE_PFN_LOCKED flags set 2717a7d1f22bSChristoph Hellwig * (destination pages must have their struct pages locked, via lock_page()). 2718a7d1f22bSChristoph Hellwig * 2719a7d1f22bSChristoph Hellwig * Note that the caller does not have to migrate all the pages that are marked 2720a7d1f22bSChristoph Hellwig * with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration from 2721a7d1f22bSChristoph Hellwig * device memory to system memory. If the caller cannot migrate a device page 2722a7d1f22bSChristoph Hellwig * back to system memory, then it must return VM_FAULT_SIGBUS, which has severe 2723a7d1f22bSChristoph Hellwig * consequences for the userspace process, so it must be avoided if at all 2724a7d1f22bSChristoph Hellwig * possible. 2725a7d1f22bSChristoph Hellwig * 2726a7d1f22bSChristoph Hellwig * For empty entries inside CPU page table (pte_none() or pmd_none() is true) we 2727a7d1f22bSChristoph Hellwig * do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus 2728f0953a1bSIngo Molnar * allowing the caller to allocate device memory for those unbacked virtual 2729f0953a1bSIngo Molnar * addresses. For this the caller simply has to allocate device memory and 2730a7d1f22bSChristoph Hellwig * properly set the destination entry like for regular migration. Note that 2731f0953a1bSIngo Molnar * this can still fail, and thus inside the device driver you must check if the 2732f0953a1bSIngo Molnar * migration was successful for those entries after calling migrate_vma_pages(), 2733a7d1f22bSChristoph Hellwig * just like for regular migration. 2734a7d1f22bSChristoph Hellwig * 2735a7d1f22bSChristoph Hellwig * After that, the callers must call migrate_vma_pages() to go over each entry 2736a7d1f22bSChristoph Hellwig * in the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag 2737a7d1f22bSChristoph Hellwig * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set, 2738a7d1f22bSChristoph Hellwig * then migrate_vma_pages() to migrate struct page information from the source 2739a7d1f22bSChristoph Hellwig * struct page to the destination struct page. If it fails to migrate the 2740a7d1f22bSChristoph Hellwig * struct page information, then it clears the MIGRATE_PFN_MIGRATE flag in the 2741a7d1f22bSChristoph Hellwig * src array. 2742a7d1f22bSChristoph Hellwig * 2743a7d1f22bSChristoph Hellwig * At this point all successfully migrated pages have an entry in the src 2744a7d1f22bSChristoph Hellwig * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst 2745a7d1f22bSChristoph Hellwig * array entry with MIGRATE_PFN_VALID flag set. 2746a7d1f22bSChristoph Hellwig * 2747a7d1f22bSChristoph Hellwig * Once migrate_vma_pages() returns the caller may inspect which pages were 2748a7d1f22bSChristoph Hellwig * successfully migrated, and which were not. Successfully migrated pages will 2749a7d1f22bSChristoph Hellwig * have the MIGRATE_PFN_MIGRATE flag set for their src array entry. 2750a7d1f22bSChristoph Hellwig * 2751a7d1f22bSChristoph Hellwig * It is safe to update device page table after migrate_vma_pages() because 2752c1e8d7c6SMichel Lespinasse * both destination and source page are still locked, and the mmap_lock is held 2753a7d1f22bSChristoph Hellwig * in read mode (hence no one can unmap the range being migrated). 2754a7d1f22bSChristoph Hellwig * 2755a7d1f22bSChristoph Hellwig * Once the caller is done cleaning up things and updating its page table (if it 2756a7d1f22bSChristoph Hellwig * chose to do so, this is not an obligation) it finally calls 2757a7d1f22bSChristoph Hellwig * migrate_vma_finalize() to update the CPU page table to point to new pages 2758a7d1f22bSChristoph Hellwig * for successfully migrated pages or otherwise restore the CPU page table to 2759a7d1f22bSChristoph Hellwig * point to the original source pages. 2760a7d1f22bSChristoph Hellwig */ 2761a7d1f22bSChristoph Hellwig int migrate_vma_setup(struct migrate_vma *args) 2762a7d1f22bSChristoph Hellwig { 2763a7d1f22bSChristoph Hellwig long nr_pages = (args->end - args->start) >> PAGE_SHIFT; 2764a7d1f22bSChristoph Hellwig 2765a7d1f22bSChristoph Hellwig args->start &= PAGE_MASK; 2766a7d1f22bSChristoph Hellwig args->end &= PAGE_MASK; 2767a7d1f22bSChristoph Hellwig if (!args->vma || is_vm_hugetlb_page(args->vma) || 2768a7d1f22bSChristoph Hellwig (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma)) 2769a7d1f22bSChristoph Hellwig return -EINVAL; 2770a7d1f22bSChristoph Hellwig if (nr_pages <= 0) 2771a7d1f22bSChristoph Hellwig return -EINVAL; 2772a7d1f22bSChristoph Hellwig if (args->start < args->vma->vm_start || 2773a7d1f22bSChristoph Hellwig args->start >= args->vma->vm_end) 2774a7d1f22bSChristoph Hellwig return -EINVAL; 2775a7d1f22bSChristoph Hellwig if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end) 2776a7d1f22bSChristoph Hellwig return -EINVAL; 2777a7d1f22bSChristoph Hellwig if (!args->src || !args->dst) 2778a7d1f22bSChristoph Hellwig return -EINVAL; 2779a7d1f22bSChristoph Hellwig 2780a7d1f22bSChristoph Hellwig memset(args->src, 0, sizeof(*args->src) * nr_pages); 2781a7d1f22bSChristoph Hellwig args->cpages = 0; 2782a7d1f22bSChristoph Hellwig args->npages = 0; 2783a7d1f22bSChristoph Hellwig 2784a7d1f22bSChristoph Hellwig migrate_vma_collect(args); 2785a7d1f22bSChristoph Hellwig 2786a7d1f22bSChristoph Hellwig if (args->cpages) 2787a7d1f22bSChristoph Hellwig migrate_vma_prepare(args); 2788a7d1f22bSChristoph Hellwig if (args->cpages) 2789a7d1f22bSChristoph Hellwig migrate_vma_unmap(args); 2790a7d1f22bSChristoph Hellwig 2791a7d1f22bSChristoph Hellwig /* 2792a7d1f22bSChristoph Hellwig * At this point pages are locked and unmapped, and thus they have 2793a7d1f22bSChristoph Hellwig * stable content and can safely be copied to destination memory that 2794a7d1f22bSChristoph Hellwig * is allocated by the drivers. 2795a7d1f22bSChristoph Hellwig */ 2796a7d1f22bSChristoph Hellwig return 0; 2797a7d1f22bSChristoph Hellwig 2798a7d1f22bSChristoph Hellwig } 2799a7d1f22bSChristoph Hellwig EXPORT_SYMBOL(migrate_vma_setup); 2800a7d1f22bSChristoph Hellwig 280134290e2cSRalph Campbell /* 280234290e2cSRalph Campbell * This code closely matches the code in: 280334290e2cSRalph Campbell * __handle_mm_fault() 280434290e2cSRalph Campbell * handle_pte_fault() 280534290e2cSRalph Campbell * do_anonymous_page() 280634290e2cSRalph Campbell * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE 280734290e2cSRalph Campbell * private page. 280834290e2cSRalph Campbell */ 28098315ada7SJérôme Glisse static void migrate_vma_insert_page(struct migrate_vma *migrate, 28108315ada7SJérôme Glisse unsigned long addr, 28118315ada7SJérôme Glisse struct page *page, 2812d85c6db4SStephen Zhang unsigned long *src) 28138315ada7SJérôme Glisse { 28148315ada7SJérôme Glisse struct vm_area_struct *vma = migrate->vma; 28158315ada7SJérôme Glisse struct mm_struct *mm = vma->vm_mm; 28168315ada7SJérôme Glisse bool flush = false; 28178315ada7SJérôme Glisse spinlock_t *ptl; 28188315ada7SJérôme Glisse pte_t entry; 28198315ada7SJérôme Glisse pgd_t *pgdp; 28208315ada7SJérôme Glisse p4d_t *p4dp; 28218315ada7SJérôme Glisse pud_t *pudp; 28228315ada7SJérôme Glisse pmd_t *pmdp; 28238315ada7SJérôme Glisse pte_t *ptep; 28248315ada7SJérôme Glisse 28258315ada7SJérôme Glisse /* Only allow populating anonymous memory */ 28268315ada7SJérôme Glisse if (!vma_is_anonymous(vma)) 28278315ada7SJérôme Glisse goto abort; 28288315ada7SJérôme Glisse 28298315ada7SJérôme Glisse pgdp = pgd_offset(mm, addr); 28308315ada7SJérôme Glisse p4dp = p4d_alloc(mm, pgdp, addr); 28318315ada7SJérôme Glisse if (!p4dp) 28328315ada7SJérôme Glisse goto abort; 28338315ada7SJérôme Glisse pudp = pud_alloc(mm, p4dp, addr); 28348315ada7SJérôme Glisse if (!pudp) 28358315ada7SJérôme Glisse goto abort; 28368315ada7SJérôme Glisse pmdp = pmd_alloc(mm, pudp, addr); 28378315ada7SJérôme Glisse if (!pmdp) 28388315ada7SJérôme Glisse goto abort; 28398315ada7SJérôme Glisse 28408315ada7SJérôme Glisse if (pmd_trans_huge(*pmdp) || pmd_devmap(*pmdp)) 28418315ada7SJérôme Glisse goto abort; 28428315ada7SJérôme Glisse 28438315ada7SJérôme Glisse /* 28448315ada7SJérôme Glisse * Use pte_alloc() instead of pte_alloc_map(). We can't run 28458315ada7SJérôme Glisse * pte_offset_map() on pmds where a huge pmd might be created 28468315ada7SJérôme Glisse * from a different thread. 28478315ada7SJérôme Glisse * 28483e4e28c5SMichel Lespinasse * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when 28498315ada7SJérôme Glisse * parallel threads are excluded by other means. 28508315ada7SJérôme Glisse * 28513e4e28c5SMichel Lespinasse * Here we only have mmap_read_lock(mm). 28528315ada7SJérôme Glisse */ 28534cf58924SJoel Fernandes (Google) if (pte_alloc(mm, pmdp)) 28548315ada7SJérôme Glisse goto abort; 28558315ada7SJérôme Glisse 28568315ada7SJérôme Glisse /* See the comment in pte_alloc_one_map() */ 28578315ada7SJérôme Glisse if (unlikely(pmd_trans_unstable(pmdp))) 28588315ada7SJérôme Glisse goto abort; 28598315ada7SJérôme Glisse 28608315ada7SJérôme Glisse if (unlikely(anon_vma_prepare(vma))) 28618315ada7SJérôme Glisse goto abort; 2862d9eb1ea2SJohannes Weiner if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL)) 28638315ada7SJérôme Glisse goto abort; 28648315ada7SJérôme Glisse 28658315ada7SJérôme Glisse /* 28668315ada7SJérôme Glisse * The memory barrier inside __SetPageUptodate makes sure that 28678315ada7SJérôme Glisse * preceding stores to the page contents become visible before 28688315ada7SJérôme Glisse * the set_pte_at() write. 28698315ada7SJérôme Glisse */ 28708315ada7SJérôme Glisse __SetPageUptodate(page); 28718315ada7SJérôme Glisse 2872df6ad698SJérôme Glisse if (is_zone_device_page(page)) { 2873df6ad698SJérôme Glisse if (is_device_private_page(page)) { 28748315ada7SJérôme Glisse swp_entry_t swp_entry; 28758315ada7SJérôme Glisse 28764dd845b5SAlistair Popple if (vma->vm_flags & VM_WRITE) 28774dd845b5SAlistair Popple swp_entry = make_writable_device_private_entry( 28784dd845b5SAlistair Popple page_to_pfn(page)); 28794dd845b5SAlistair Popple else 28804dd845b5SAlistair Popple swp_entry = make_readable_device_private_entry( 28814dd845b5SAlistair Popple page_to_pfn(page)); 28828315ada7SJérôme Glisse entry = swp_entry_to_pte(swp_entry); 288334f5e9b9SMiaohe Lin } else { 288434f5e9b9SMiaohe Lin /* 288534f5e9b9SMiaohe Lin * For now we only support migrating to un-addressable 288634f5e9b9SMiaohe Lin * device memory. 288734f5e9b9SMiaohe Lin */ 288834f5e9b9SMiaohe Lin pr_warn_once("Unsupported ZONE_DEVICE page type.\n"); 288934f5e9b9SMiaohe Lin goto abort; 2890df6ad698SJérôme Glisse } 28918315ada7SJérôme Glisse } else { 28928315ada7SJérôme Glisse entry = mk_pte(page, vma->vm_page_prot); 28938315ada7SJérôme Glisse if (vma->vm_flags & VM_WRITE) 28948315ada7SJérôme Glisse entry = pte_mkwrite(pte_mkdirty(entry)); 28958315ada7SJérôme Glisse } 28968315ada7SJérôme Glisse 28978315ada7SJérôme Glisse ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); 28988315ada7SJérôme Glisse 289934290e2cSRalph Campbell if (check_stable_address_space(mm)) 290034290e2cSRalph Campbell goto unlock_abort; 290134290e2cSRalph Campbell 29028315ada7SJérôme Glisse if (pte_present(*ptep)) { 29038315ada7SJérôme Glisse unsigned long pfn = pte_pfn(*ptep); 29048315ada7SJérôme Glisse 2905c23a0c99SRalph Campbell if (!is_zero_pfn(pfn)) 2906c23a0c99SRalph Campbell goto unlock_abort; 29078315ada7SJérôme Glisse flush = true; 2908c23a0c99SRalph Campbell } else if (!pte_none(*ptep)) 2909c23a0c99SRalph Campbell goto unlock_abort; 29108315ada7SJérôme Glisse 29118315ada7SJérôme Glisse /* 2912c23a0c99SRalph Campbell * Check for userfaultfd but do not deliver the fault. Instead, 29138315ada7SJérôme Glisse * just back off. 29148315ada7SJérôme Glisse */ 2915c23a0c99SRalph Campbell if (userfaultfd_missing(vma)) 2916c23a0c99SRalph Campbell goto unlock_abort; 29178315ada7SJérôme Glisse 29188315ada7SJérôme Glisse inc_mm_counter(mm, MM_ANONPAGES); 2919be5d0a74SJohannes Weiner page_add_new_anon_rmap(page, vma, addr, false); 29208315ada7SJérôme Glisse if (!is_zone_device_page(page)) 2921b518154eSJoonsoo Kim lru_cache_add_inactive_or_unevictable(page, vma); 29228315ada7SJérôme Glisse get_page(page); 29238315ada7SJérôme Glisse 29248315ada7SJérôme Glisse if (flush) { 29258315ada7SJérôme Glisse flush_cache_page(vma, addr, pte_pfn(*ptep)); 29268315ada7SJérôme Glisse ptep_clear_flush_notify(vma, addr, ptep); 29278315ada7SJérôme Glisse set_pte_at_notify(mm, addr, ptep, entry); 29288315ada7SJérôme Glisse update_mmu_cache(vma, addr, ptep); 29298315ada7SJérôme Glisse } else { 29308315ada7SJérôme Glisse /* No need to invalidate - it was non-present before */ 29318315ada7SJérôme Glisse set_pte_at(mm, addr, ptep, entry); 29328315ada7SJérôme Glisse update_mmu_cache(vma, addr, ptep); 29338315ada7SJérôme Glisse } 29348315ada7SJérôme Glisse 29358315ada7SJérôme Glisse pte_unmap_unlock(ptep, ptl); 29368315ada7SJérôme Glisse *src = MIGRATE_PFN_MIGRATE; 29378315ada7SJérôme Glisse return; 29388315ada7SJérôme Glisse 2939c23a0c99SRalph Campbell unlock_abort: 2940c23a0c99SRalph Campbell pte_unmap_unlock(ptep, ptl); 29418315ada7SJérôme Glisse abort: 29428315ada7SJérôme Glisse *src &= ~MIGRATE_PFN_MIGRATE; 29438315ada7SJérôme Glisse } 29448315ada7SJérôme Glisse 2945a7d1f22bSChristoph Hellwig /** 29468763cb45SJérôme Glisse * migrate_vma_pages() - migrate meta-data from src page to dst page 29478763cb45SJérôme Glisse * @migrate: migrate struct containing all migration information 29488763cb45SJérôme Glisse * 29498763cb45SJérôme Glisse * This migrates struct page meta-data from source struct page to destination 29508763cb45SJérôme Glisse * struct page. This effectively finishes the migration from source page to the 29518763cb45SJérôme Glisse * destination page. 29528763cb45SJérôme Glisse */ 2953a7d1f22bSChristoph Hellwig void migrate_vma_pages(struct migrate_vma *migrate) 29548763cb45SJérôme Glisse { 29558763cb45SJérôme Glisse const unsigned long npages = migrate->npages; 29568763cb45SJérôme Glisse const unsigned long start = migrate->start; 2957ac46d4f3SJérôme Glisse struct mmu_notifier_range range; 2958ac46d4f3SJérôme Glisse unsigned long addr, i; 29598315ada7SJérôme Glisse bool notified = false; 29608763cb45SJérôme Glisse 29618763cb45SJérôme Glisse for (i = 0, addr = start; i < npages; addr += PAGE_SIZE, i++) { 29628763cb45SJérôme Glisse struct page *newpage = migrate_pfn_to_page(migrate->dst[i]); 29638763cb45SJérôme Glisse struct page *page = migrate_pfn_to_page(migrate->src[i]); 29648763cb45SJérôme Glisse struct address_space *mapping; 29658763cb45SJérôme Glisse int r; 29668763cb45SJérôme Glisse 29678315ada7SJérôme Glisse if (!newpage) { 29688315ada7SJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 29698763cb45SJérôme Glisse continue; 29708315ada7SJérôme Glisse } 29718315ada7SJérôme Glisse 29728315ada7SJérôme Glisse if (!page) { 2973c23a0c99SRalph Campbell if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE)) 29748763cb45SJérôme Glisse continue; 29758315ada7SJérôme Glisse if (!notified) { 29768315ada7SJérôme Glisse notified = true; 2977ac46d4f3SJérôme Glisse 29786b49bf6dSAlistair Popple mmu_notifier_range_init_owner(&range, 29796b49bf6dSAlistair Popple MMU_NOTIFY_MIGRATE, 0, migrate->vma, 29806b49bf6dSAlistair Popple migrate->vma->vm_mm, addr, migrate->end, 29815e5dda81SRalph Campbell migrate->pgmap_owner); 2982ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_start(&range); 29838315ada7SJérôme Glisse } 29848315ada7SJérôme Glisse migrate_vma_insert_page(migrate, addr, newpage, 2985d85c6db4SStephen Zhang &migrate->src[i]); 29868315ada7SJérôme Glisse continue; 29878315ada7SJérôme Glisse } 29888763cb45SJérôme Glisse 29898763cb45SJérôme Glisse mapping = page_mapping(page); 29908763cb45SJérôme Glisse 2991a5430ddaSJérôme Glisse if (is_zone_device_page(newpage)) { 2992a5430ddaSJérôme Glisse if (is_device_private_page(newpage)) { 2993a5430ddaSJérôme Glisse /* 2994a5430ddaSJérôme Glisse * For now only support private anonymous when 2995a5430ddaSJérôme Glisse * migrating to un-addressable device memory. 2996a5430ddaSJérôme Glisse */ 2997a5430ddaSJérôme Glisse if (mapping) { 2998a5430ddaSJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 2999a5430ddaSJérôme Glisse continue; 3000a5430ddaSJérôme Glisse } 300125b2995aSChristoph Hellwig } else { 3002a5430ddaSJérôme Glisse /* 3003a5430ddaSJérôme Glisse * Other types of ZONE_DEVICE page are not 3004a5430ddaSJérôme Glisse * supported. 3005a5430ddaSJérôme Glisse */ 3006a5430ddaSJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 3007a5430ddaSJérôme Glisse continue; 3008a5430ddaSJérôme Glisse } 3009a5430ddaSJérôme Glisse } 3010a5430ddaSJérôme Glisse 30118763cb45SJérôme Glisse r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY); 30128763cb45SJérôme Glisse if (r != MIGRATEPAGE_SUCCESS) 30138763cb45SJérôme Glisse migrate->src[i] &= ~MIGRATE_PFN_MIGRATE; 30148763cb45SJérôme Glisse } 30158315ada7SJérôme Glisse 30164645b9feSJérôme Glisse /* 30174645b9feSJérôme Glisse * No need to double call mmu_notifier->invalidate_range() callback as 30184645b9feSJérôme Glisse * the above ptep_clear_flush_notify() inside migrate_vma_insert_page() 30194645b9feSJérôme Glisse * did already call it. 30204645b9feSJérôme Glisse */ 30218315ada7SJérôme Glisse if (notified) 3022ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_only_end(&range); 30238763cb45SJérôme Glisse } 3024a7d1f22bSChristoph Hellwig EXPORT_SYMBOL(migrate_vma_pages); 30258763cb45SJérôme Glisse 3026a7d1f22bSChristoph Hellwig /** 30278763cb45SJérôme Glisse * migrate_vma_finalize() - restore CPU page table entry 30288763cb45SJérôme Glisse * @migrate: migrate struct containing all migration information 30298763cb45SJérôme Glisse * 30308763cb45SJérôme Glisse * This replaces the special migration pte entry with either a mapping to the 30318763cb45SJérôme Glisse * new page if migration was successful for that page, or to the original page 30328763cb45SJérôme Glisse * otherwise. 30338763cb45SJérôme Glisse * 30348763cb45SJérôme Glisse * This also unlocks the pages and puts them back on the lru, or drops the extra 30358763cb45SJérôme Glisse * refcount, for device pages. 30368763cb45SJérôme Glisse */ 3037a7d1f22bSChristoph Hellwig void migrate_vma_finalize(struct migrate_vma *migrate) 30388763cb45SJérôme Glisse { 30398763cb45SJérôme Glisse const unsigned long npages = migrate->npages; 30408763cb45SJérôme Glisse unsigned long i; 30418763cb45SJérôme Glisse 30428763cb45SJérôme Glisse for (i = 0; i < npages; i++) { 30438763cb45SJérôme Glisse struct page *newpage = migrate_pfn_to_page(migrate->dst[i]); 30448763cb45SJérôme Glisse struct page *page = migrate_pfn_to_page(migrate->src[i]); 30458763cb45SJérôme Glisse 30468315ada7SJérôme Glisse if (!page) { 30478315ada7SJérôme Glisse if (newpage) { 30488315ada7SJérôme Glisse unlock_page(newpage); 30498315ada7SJérôme Glisse put_page(newpage); 30508315ada7SJérôme Glisse } 30518763cb45SJérôme Glisse continue; 30528315ada7SJérôme Glisse } 30538315ada7SJérôme Glisse 30548763cb45SJérôme Glisse if (!(migrate->src[i] & MIGRATE_PFN_MIGRATE) || !newpage) { 30558763cb45SJérôme Glisse if (newpage) { 30568763cb45SJérôme Glisse unlock_page(newpage); 30578763cb45SJérôme Glisse put_page(newpage); 30588763cb45SJérôme Glisse } 30598763cb45SJérôme Glisse newpage = page; 30608763cb45SJérôme Glisse } 30618763cb45SJérôme Glisse 30628763cb45SJérôme Glisse remove_migration_ptes(page, newpage, false); 30638763cb45SJérôme Glisse unlock_page(page); 30648763cb45SJérôme Glisse 3065a5430ddaSJérôme Glisse if (is_zone_device_page(page)) 3066a5430ddaSJérôme Glisse put_page(page); 3067a5430ddaSJérôme Glisse else 30688763cb45SJérôme Glisse putback_lru_page(page); 30698763cb45SJérôme Glisse 30708763cb45SJérôme Glisse if (newpage != page) { 30718763cb45SJérôme Glisse unlock_page(newpage); 3072a5430ddaSJérôme Glisse if (is_zone_device_page(newpage)) 3073a5430ddaSJérôme Glisse put_page(newpage); 3074a5430ddaSJérôme Glisse else 30758763cb45SJérôme Glisse putback_lru_page(newpage); 30768763cb45SJérôme Glisse } 30778763cb45SJérôme Glisse } 30788763cb45SJérôme Glisse } 3079a7d1f22bSChristoph Hellwig EXPORT_SYMBOL(migrate_vma_finalize); 30809b2ed9cbSChristoph Hellwig #endif /* CONFIG_DEVICE_PRIVATE */ 308179c28a41SDave Hansen 3082884a6e5dSDave Hansen #if defined(CONFIG_MEMORY_HOTPLUG) 308379c28a41SDave Hansen /* Disable reclaim-based migration. */ 308479c28a41SDave Hansen static void __disable_all_migrate_targets(void) 308579c28a41SDave Hansen { 308679c28a41SDave Hansen int node; 308779c28a41SDave Hansen 308879c28a41SDave Hansen for_each_online_node(node) 308979c28a41SDave Hansen node_demotion[node] = NUMA_NO_NODE; 309079c28a41SDave Hansen } 309179c28a41SDave Hansen 309279c28a41SDave Hansen static void disable_all_migrate_targets(void) 309379c28a41SDave Hansen { 309479c28a41SDave Hansen __disable_all_migrate_targets(); 309579c28a41SDave Hansen 309679c28a41SDave Hansen /* 309779c28a41SDave Hansen * Ensure that the "disable" is visible across the system. 309879c28a41SDave Hansen * Readers will see either a combination of before+disable 309979c28a41SDave Hansen * state or disable+after. They will never see before and 310079c28a41SDave Hansen * after state together. 310179c28a41SDave Hansen * 310279c28a41SDave Hansen * The before+after state together might have cycles and 310379c28a41SDave Hansen * could cause readers to do things like loop until this 310479c28a41SDave Hansen * function finishes. This ensures they can only see a 310579c28a41SDave Hansen * single "bad" read and would, for instance, only loop 310679c28a41SDave Hansen * once. 310779c28a41SDave Hansen */ 310879c28a41SDave Hansen synchronize_rcu(); 310979c28a41SDave Hansen } 311079c28a41SDave Hansen 311179c28a41SDave Hansen /* 311279c28a41SDave Hansen * Find an automatic demotion target for 'node'. 311379c28a41SDave Hansen * Failing here is OK. It might just indicate 311479c28a41SDave Hansen * being at the end of a chain. 311579c28a41SDave Hansen */ 311679c28a41SDave Hansen static int establish_migrate_target(int node, nodemask_t *used) 311779c28a41SDave Hansen { 311879c28a41SDave Hansen int migration_target; 311979c28a41SDave Hansen 312079c28a41SDave Hansen /* 312179c28a41SDave Hansen * Can not set a migration target on a 312279c28a41SDave Hansen * node with it already set. 312379c28a41SDave Hansen * 312479c28a41SDave Hansen * No need for READ_ONCE() here since this 312579c28a41SDave Hansen * in the write path for node_demotion[]. 312679c28a41SDave Hansen * This should be the only thread writing. 312779c28a41SDave Hansen */ 312879c28a41SDave Hansen if (node_demotion[node] != NUMA_NO_NODE) 312979c28a41SDave Hansen return NUMA_NO_NODE; 313079c28a41SDave Hansen 313179c28a41SDave Hansen migration_target = find_next_best_node(node, used); 313279c28a41SDave Hansen if (migration_target == NUMA_NO_NODE) 313379c28a41SDave Hansen return NUMA_NO_NODE; 313479c28a41SDave Hansen 313579c28a41SDave Hansen node_demotion[node] = migration_target; 313679c28a41SDave Hansen 313779c28a41SDave Hansen return migration_target; 313879c28a41SDave Hansen } 313979c28a41SDave Hansen 314079c28a41SDave Hansen /* 314179c28a41SDave Hansen * When memory fills up on a node, memory contents can be 314279c28a41SDave Hansen * automatically migrated to another node instead of 314379c28a41SDave Hansen * discarded at reclaim. 314479c28a41SDave Hansen * 314579c28a41SDave Hansen * Establish a "migration path" which will start at nodes 314679c28a41SDave Hansen * with CPUs and will follow the priorities used to build the 314779c28a41SDave Hansen * page allocator zonelists. 314879c28a41SDave Hansen * 314979c28a41SDave Hansen * The difference here is that cycles must be avoided. If 315079c28a41SDave Hansen * node0 migrates to node1, then neither node1, nor anything 315179c28a41SDave Hansen * node1 migrates to can migrate to node0. 315279c28a41SDave Hansen * 315379c28a41SDave Hansen * This function can run simultaneously with readers of 315479c28a41SDave Hansen * node_demotion[]. However, it can not run simultaneously 315579c28a41SDave Hansen * with itself. Exclusion is provided by memory hotplug events 315679c28a41SDave Hansen * being single-threaded. 315779c28a41SDave Hansen */ 315879c28a41SDave Hansen static void __set_migration_target_nodes(void) 315979c28a41SDave Hansen { 316079c28a41SDave Hansen nodemask_t next_pass = NODE_MASK_NONE; 316179c28a41SDave Hansen nodemask_t this_pass = NODE_MASK_NONE; 316279c28a41SDave Hansen nodemask_t used_targets = NODE_MASK_NONE; 316379c28a41SDave Hansen int node; 316479c28a41SDave Hansen 316579c28a41SDave Hansen /* 316679c28a41SDave Hansen * Avoid any oddities like cycles that could occur 316779c28a41SDave Hansen * from changes in the topology. This will leave 316879c28a41SDave Hansen * a momentary gap when migration is disabled. 316979c28a41SDave Hansen */ 317079c28a41SDave Hansen disable_all_migrate_targets(); 317179c28a41SDave Hansen 317279c28a41SDave Hansen /* 317379c28a41SDave Hansen * Allocations go close to CPUs, first. Assume that 317479c28a41SDave Hansen * the migration path starts at the nodes with CPUs. 317579c28a41SDave Hansen */ 317679c28a41SDave Hansen next_pass = node_states[N_CPU]; 317779c28a41SDave Hansen again: 317879c28a41SDave Hansen this_pass = next_pass; 317979c28a41SDave Hansen next_pass = NODE_MASK_NONE; 318079c28a41SDave Hansen /* 318179c28a41SDave Hansen * To avoid cycles in the migration "graph", ensure 318279c28a41SDave Hansen * that migration sources are not future targets by 318379c28a41SDave Hansen * setting them in 'used_targets'. Do this only 318479c28a41SDave Hansen * once per pass so that multiple source nodes can 318579c28a41SDave Hansen * share a target node. 318679c28a41SDave Hansen * 318779c28a41SDave Hansen * 'used_targets' will become unavailable in future 318879c28a41SDave Hansen * passes. This limits some opportunities for 318979c28a41SDave Hansen * multiple source nodes to share a destination. 319079c28a41SDave Hansen */ 319179c28a41SDave Hansen nodes_or(used_targets, used_targets, this_pass); 319279c28a41SDave Hansen for_each_node_mask(node, this_pass) { 319379c28a41SDave Hansen int target_node = establish_migrate_target(node, &used_targets); 319479c28a41SDave Hansen 319579c28a41SDave Hansen if (target_node == NUMA_NO_NODE) 319679c28a41SDave Hansen continue; 319779c28a41SDave Hansen 319879c28a41SDave Hansen /* 319979c28a41SDave Hansen * Visit targets from this pass in the next pass. 320079c28a41SDave Hansen * Eventually, every node will have been part of 320179c28a41SDave Hansen * a pass, and will become set in 'used_targets'. 320279c28a41SDave Hansen */ 320379c28a41SDave Hansen node_set(target_node, next_pass); 320479c28a41SDave Hansen } 320579c28a41SDave Hansen /* 320679c28a41SDave Hansen * 'next_pass' contains nodes which became migration 320779c28a41SDave Hansen * targets in this pass. Make additional passes until 320879c28a41SDave Hansen * no more migrations targets are available. 320979c28a41SDave Hansen */ 321079c28a41SDave Hansen if (!nodes_empty(next_pass)) 321179c28a41SDave Hansen goto again; 321279c28a41SDave Hansen } 321379c28a41SDave Hansen 321479c28a41SDave Hansen /* 321579c28a41SDave Hansen * For callers that do not hold get_online_mems() already. 321679c28a41SDave Hansen */ 321779c28a41SDave Hansen static void set_migration_target_nodes(void) 321879c28a41SDave Hansen { 321979c28a41SDave Hansen get_online_mems(); 322079c28a41SDave Hansen __set_migration_target_nodes(); 322179c28a41SDave Hansen put_online_mems(); 322279c28a41SDave Hansen } 3223884a6e5dSDave Hansen 3224884a6e5dSDave Hansen /* 3225884a6e5dSDave Hansen * React to hotplug events that might affect the migration targets 3226884a6e5dSDave Hansen * like events that online or offline NUMA nodes. 3227884a6e5dSDave Hansen * 3228884a6e5dSDave Hansen * The ordering is also currently dependent on which nodes have 3229884a6e5dSDave Hansen * CPUs. That means we need CPU on/offline notification too. 3230884a6e5dSDave Hansen */ 3231884a6e5dSDave Hansen static int migration_online_cpu(unsigned int cpu) 3232884a6e5dSDave Hansen { 3233884a6e5dSDave Hansen set_migration_target_nodes(); 3234884a6e5dSDave Hansen return 0; 3235884a6e5dSDave Hansen } 3236884a6e5dSDave Hansen 3237884a6e5dSDave Hansen static int migration_offline_cpu(unsigned int cpu) 3238884a6e5dSDave Hansen { 3239884a6e5dSDave Hansen set_migration_target_nodes(); 3240884a6e5dSDave Hansen return 0; 3241884a6e5dSDave Hansen } 3242884a6e5dSDave Hansen 3243884a6e5dSDave Hansen /* 3244884a6e5dSDave Hansen * This leaves migrate-on-reclaim transiently disabled between 3245884a6e5dSDave Hansen * the MEM_GOING_OFFLINE and MEM_OFFLINE events. This runs 3246884a6e5dSDave Hansen * whether reclaim-based migration is enabled or not, which 3247884a6e5dSDave Hansen * ensures that the user can turn reclaim-based migration at 3248884a6e5dSDave Hansen * any time without needing to recalculate migration targets. 3249884a6e5dSDave Hansen * 3250884a6e5dSDave Hansen * These callbacks already hold get_online_mems(). That is why 3251884a6e5dSDave Hansen * __set_migration_target_nodes() can be used as opposed to 3252884a6e5dSDave Hansen * set_migration_target_nodes(). 3253884a6e5dSDave Hansen */ 3254884a6e5dSDave Hansen static int __meminit migrate_on_reclaim_callback(struct notifier_block *self, 3255884a6e5dSDave Hansen unsigned long action, void *arg) 3256884a6e5dSDave Hansen { 3257884a6e5dSDave Hansen switch (action) { 3258884a6e5dSDave Hansen case MEM_GOING_OFFLINE: 3259884a6e5dSDave Hansen /* 3260884a6e5dSDave Hansen * Make sure there are not transient states where 3261884a6e5dSDave Hansen * an offline node is a migration target. This 3262884a6e5dSDave Hansen * will leave migration disabled until the offline 3263884a6e5dSDave Hansen * completes and the MEM_OFFLINE case below runs. 3264884a6e5dSDave Hansen */ 3265884a6e5dSDave Hansen disable_all_migrate_targets(); 3266884a6e5dSDave Hansen break; 3267884a6e5dSDave Hansen case MEM_OFFLINE: 3268884a6e5dSDave Hansen case MEM_ONLINE: 3269884a6e5dSDave Hansen /* 3270884a6e5dSDave Hansen * Recalculate the target nodes once the node 3271884a6e5dSDave Hansen * reaches its final state (online or offline). 3272884a6e5dSDave Hansen */ 3273884a6e5dSDave Hansen __set_migration_target_nodes(); 3274884a6e5dSDave Hansen break; 3275884a6e5dSDave Hansen case MEM_CANCEL_OFFLINE: 3276884a6e5dSDave Hansen /* 3277884a6e5dSDave Hansen * MEM_GOING_OFFLINE disabled all the migration 3278884a6e5dSDave Hansen * targets. Reenable them. 3279884a6e5dSDave Hansen */ 3280884a6e5dSDave Hansen __set_migration_target_nodes(); 3281884a6e5dSDave Hansen break; 3282884a6e5dSDave Hansen case MEM_GOING_ONLINE: 3283884a6e5dSDave Hansen case MEM_CANCEL_ONLINE: 3284884a6e5dSDave Hansen break; 3285884a6e5dSDave Hansen } 3286884a6e5dSDave Hansen 3287884a6e5dSDave Hansen return notifier_from_errno(0); 3288884a6e5dSDave Hansen } 3289884a6e5dSDave Hansen 3290884a6e5dSDave Hansen static int __init migrate_on_reclaim_init(void) 3291884a6e5dSDave Hansen { 3292884a6e5dSDave Hansen int ret; 3293884a6e5dSDave Hansen 3294884a6e5dSDave Hansen ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "migrate on reclaim", 3295884a6e5dSDave Hansen migration_online_cpu, 3296884a6e5dSDave Hansen migration_offline_cpu); 3297884a6e5dSDave Hansen /* 3298884a6e5dSDave Hansen * In the unlikely case that this fails, the automatic 3299884a6e5dSDave Hansen * migration targets may become suboptimal for nodes 3300884a6e5dSDave Hansen * where N_CPU changes. With such a small impact in a 3301884a6e5dSDave Hansen * rare case, do not bother trying to do anything special. 3302884a6e5dSDave Hansen */ 3303884a6e5dSDave Hansen WARN_ON(ret < 0); 3304884a6e5dSDave Hansen 3305884a6e5dSDave Hansen hotplug_memory_notifier(migrate_on_reclaim_callback, 100); 3306884a6e5dSDave Hansen return 0; 3307884a6e5dSDave Hansen } 3308884a6e5dSDave Hansen late_initcall(migrate_on_reclaim_init); 3309884a6e5dSDave Hansen #endif /* CONFIG_MEMORY_HOTPLUG */ 3310