11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * mm/rmap.c - physical to virtual reverse mappings 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright 2001, Rik van Riel <riel@conectiva.com.br> 51da177e4SLinus Torvalds * Released under the General Public License (GPL). 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Simple, low overhead reverse mapping scheme. 81da177e4SLinus Torvalds * Please try to keep this thing as modular as possible. 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * Provides methods for unmapping each kind of mapped page: 111da177e4SLinus Torvalds * the anon methods track anonymous pages, and 121da177e4SLinus Torvalds * the file methods track pages belonging to an inode. 131da177e4SLinus Torvalds * 141da177e4SLinus Torvalds * Original design by Rik van Riel <riel@conectiva.com.br> 2001 151da177e4SLinus Torvalds * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 161da177e4SLinus Torvalds * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 1798f32602SHugh Dickins * Contributions by Hugh Dickins 2003, 2004 181da177e4SLinus Torvalds */ 191da177e4SLinus Torvalds 201da177e4SLinus Torvalds /* 211da177e4SLinus Torvalds * Lock ordering in mm: 221da177e4SLinus Torvalds * 239608703eSJan Kara * inode->i_rwsem (while writing or truncating, not reading or faulting) 24c1e8d7c6SMichel Lespinasse * mm->mmap_lock 25730633f0SJan Kara * mapping->invalidate_lock (in filemap_fault) 269608703eSJan Kara * page->flags PG_locked (lock_page) * (see hugetlbfs below) 2788f306b6SKirill A. Shutemov * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share) 28c8c06efaSDavidlohr Bueso * mapping->i_mmap_rwsem 29c0d0381aSMike Kravetz * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) 305a505085SIngo Molnar * anon_vma->rwsem 31b8072f09SHugh Dickins * mm->page_table_lock or pte_lock 325d337b91SHugh Dickins * swap_lock (in swap_duplicate, swap_info_get) 331da177e4SLinus Torvalds * mmlist_lock (in mmput, drain_mmlist and others) 341da177e4SLinus Torvalds * mapping->private_lock (in __set_page_dirty_buffers) 3515b44736SHugh Dickins * lock_page_memcg move_lock (in __set_page_dirty_buffers) 36b93b0163SMatthew Wilcox * i_pages lock (widely used) 37e809c3feSMatthew Wilcox (Oracle) * lruvec->lru_lock (in folio_lruvec_lock_irq) 38250df6edSDave Chinner * inode->i_lock (in set_page_dirty's __mark_inode_dirty) 39f758eeabSChristoph Hellwig * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) 401da177e4SLinus Torvalds * sb_lock (within inode_lock in fs/fs-writeback.c) 41b93b0163SMatthew Wilcox * i_pages lock (widely used, in set_page_dirty, 421da177e4SLinus Torvalds * in arch-dependent flush_dcache_mmap_lock, 43f758eeabSChristoph Hellwig * within bdi.wb->list_lock in __sync_single_inode) 446a46079cSAndi Kleen * 459608703eSJan Kara * anon_vma->rwsem,mapping->i_mmap_rwsem (memory_failure, collect_procs_anon) 466a46079cSAndi Kleen * ->tasklist_lock 476a46079cSAndi Kleen * pte map lock 48c0d0381aSMike Kravetz * 49c0d0381aSMike Kravetz * * hugetlbfs PageHuge() pages take locks in this order: 50c0d0381aSMike Kravetz * mapping->i_mmap_rwsem 51c0d0381aSMike Kravetz * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) 52c0d0381aSMike Kravetz * page->flags PG_locked (lock_page) 531da177e4SLinus Torvalds */ 541da177e4SLinus Torvalds 551da177e4SLinus Torvalds #include <linux/mm.h> 566e84f315SIngo Molnar #include <linux/sched/mm.h> 5729930025SIngo Molnar #include <linux/sched/task.h> 581da177e4SLinus Torvalds #include <linux/pagemap.h> 591da177e4SLinus Torvalds #include <linux/swap.h> 601da177e4SLinus Torvalds #include <linux/swapops.h> 611da177e4SLinus Torvalds #include <linux/slab.h> 621da177e4SLinus Torvalds #include <linux/init.h> 635ad64688SHugh Dickins #include <linux/ksm.h> 641da177e4SLinus Torvalds #include <linux/rmap.h> 651da177e4SLinus Torvalds #include <linux/rcupdate.h> 66b95f1b31SPaul Gortmaker #include <linux/export.h> 678a9f3ccdSBalbir Singh #include <linux/memcontrol.h> 68cddb8a5cSAndrea Arcangeli #include <linux/mmu_notifier.h> 6964cdd548SKOSAKI Motohiro #include <linux/migrate.h> 700fe6e20bSNaoya Horiguchi #include <linux/hugetlb.h> 71444f84fdSBen Dooks #include <linux/huge_mm.h> 72ef5d437fSJan Kara #include <linux/backing-dev.h> 7333c3fc71SVladimir Davydov #include <linux/page_idle.h> 74a5430ddaSJérôme Glisse #include <linux/memremap.h> 75bce73e48SChristian Borntraeger #include <linux/userfaultfd_k.h> 761da177e4SLinus Torvalds 771da177e4SLinus Torvalds #include <asm/tlbflush.h> 781da177e4SLinus Torvalds 7972b252aeSMel Gorman #include <trace/events/tlb.h> 8072b252aeSMel Gorman 81b291f000SNick Piggin #include "internal.h" 82b291f000SNick Piggin 83fdd2e5f8SAdrian Bunk static struct kmem_cache *anon_vma_cachep; 845beb4930SRik van Riel static struct kmem_cache *anon_vma_chain_cachep; 85fdd2e5f8SAdrian Bunk 86fdd2e5f8SAdrian Bunk static inline struct anon_vma *anon_vma_alloc(void) 87fdd2e5f8SAdrian Bunk { 8801d8b20dSPeter Zijlstra struct anon_vma *anon_vma; 8901d8b20dSPeter Zijlstra 9001d8b20dSPeter Zijlstra anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); 9101d8b20dSPeter Zijlstra if (anon_vma) { 9201d8b20dSPeter Zijlstra atomic_set(&anon_vma->refcount, 1); 937a3ef208SKonstantin Khlebnikov anon_vma->degree = 1; /* Reference for first vma */ 947a3ef208SKonstantin Khlebnikov anon_vma->parent = anon_vma; 9501d8b20dSPeter Zijlstra /* 9601d8b20dSPeter Zijlstra * Initialise the anon_vma root to point to itself. If called 9701d8b20dSPeter Zijlstra * from fork, the root will be reset to the parents anon_vma. 9801d8b20dSPeter Zijlstra */ 9901d8b20dSPeter Zijlstra anon_vma->root = anon_vma; 100fdd2e5f8SAdrian Bunk } 101fdd2e5f8SAdrian Bunk 10201d8b20dSPeter Zijlstra return anon_vma; 10301d8b20dSPeter Zijlstra } 10401d8b20dSPeter Zijlstra 10501d8b20dSPeter Zijlstra static inline void anon_vma_free(struct anon_vma *anon_vma) 106fdd2e5f8SAdrian Bunk { 10701d8b20dSPeter Zijlstra VM_BUG_ON(atomic_read(&anon_vma->refcount)); 10888c22088SPeter Zijlstra 10988c22088SPeter Zijlstra /* 1104fc3f1d6SIngo Molnar * Synchronize against page_lock_anon_vma_read() such that 11188c22088SPeter Zijlstra * we can safely hold the lock without the anon_vma getting 11288c22088SPeter Zijlstra * freed. 11388c22088SPeter Zijlstra * 11488c22088SPeter Zijlstra * Relies on the full mb implied by the atomic_dec_and_test() from 11588c22088SPeter Zijlstra * put_anon_vma() against the acquire barrier implied by 1164fc3f1d6SIngo Molnar * down_read_trylock() from page_lock_anon_vma_read(). This orders: 11788c22088SPeter Zijlstra * 1184fc3f1d6SIngo Molnar * page_lock_anon_vma_read() VS put_anon_vma() 1194fc3f1d6SIngo Molnar * down_read_trylock() atomic_dec_and_test() 12088c22088SPeter Zijlstra * LOCK MB 1214fc3f1d6SIngo Molnar * atomic_read() rwsem_is_locked() 12288c22088SPeter Zijlstra * 12388c22088SPeter Zijlstra * LOCK should suffice since the actual taking of the lock must 12488c22088SPeter Zijlstra * happen _before_ what follows. 12588c22088SPeter Zijlstra */ 1267f39dda9SHugh Dickins might_sleep(); 1275a505085SIngo Molnar if (rwsem_is_locked(&anon_vma->root->rwsem)) { 1284fc3f1d6SIngo Molnar anon_vma_lock_write(anon_vma); 12908b52706SKonstantin Khlebnikov anon_vma_unlock_write(anon_vma); 13088c22088SPeter Zijlstra } 13188c22088SPeter Zijlstra 132fdd2e5f8SAdrian Bunk kmem_cache_free(anon_vma_cachep, anon_vma); 133fdd2e5f8SAdrian Bunk } 1341da177e4SLinus Torvalds 135dd34739cSLinus Torvalds static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp) 1365beb4930SRik van Riel { 137dd34739cSLinus Torvalds return kmem_cache_alloc(anon_vma_chain_cachep, gfp); 1385beb4930SRik van Riel } 1395beb4930SRik van Riel 140e574b5fdSNamhyung Kim static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) 1415beb4930SRik van Riel { 1425beb4930SRik van Riel kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); 1435beb4930SRik van Riel } 1445beb4930SRik van Riel 1456583a843SKautuk Consul static void anon_vma_chain_link(struct vm_area_struct *vma, 1466583a843SKautuk Consul struct anon_vma_chain *avc, 1476583a843SKautuk Consul struct anon_vma *anon_vma) 1486583a843SKautuk Consul { 1496583a843SKautuk Consul avc->vma = vma; 1506583a843SKautuk Consul avc->anon_vma = anon_vma; 1516583a843SKautuk Consul list_add(&avc->same_vma, &vma->anon_vma_chain); 152bf181b9fSMichel Lespinasse anon_vma_interval_tree_insert(avc, &anon_vma->rb_root); 1536583a843SKautuk Consul } 1546583a843SKautuk Consul 155d9d332e0SLinus Torvalds /** 156d5a187daSVlastimil Babka * __anon_vma_prepare - attach an anon_vma to a memory region 157d9d332e0SLinus Torvalds * @vma: the memory region in question 158d9d332e0SLinus Torvalds * 159d9d332e0SLinus Torvalds * This makes sure the memory mapping described by 'vma' has 160d9d332e0SLinus Torvalds * an 'anon_vma' attached to it, so that we can associate the 161d9d332e0SLinus Torvalds * anonymous pages mapped into it with that anon_vma. 162d9d332e0SLinus Torvalds * 163d5a187daSVlastimil Babka * The common case will be that we already have one, which 164d5a187daSVlastimil Babka * is handled inline by anon_vma_prepare(). But if 16523a0790aSFigo.zhang * not we either need to find an adjacent mapping that we 166d9d332e0SLinus Torvalds * can re-use the anon_vma from (very common when the only 167d9d332e0SLinus Torvalds * reason for splitting a vma has been mprotect()), or we 168d9d332e0SLinus Torvalds * allocate a new one. 169d9d332e0SLinus Torvalds * 170d9d332e0SLinus Torvalds * Anon-vma allocations are very subtle, because we may have 1714fc3f1d6SIngo Molnar * optimistically looked up an anon_vma in page_lock_anon_vma_read() 172aaf1f990SMiaohe Lin * and that may actually touch the rwsem even in the newly 173d9d332e0SLinus Torvalds * allocated vma (it depends on RCU to make sure that the 174d9d332e0SLinus Torvalds * anon_vma isn't actually destroyed). 175d9d332e0SLinus Torvalds * 176d9d332e0SLinus Torvalds * As a result, we need to do proper anon_vma locking even 177d9d332e0SLinus Torvalds * for the new allocation. At the same time, we do not want 178d9d332e0SLinus Torvalds * to do any locking for the common case of already having 179d9d332e0SLinus Torvalds * an anon_vma. 180d9d332e0SLinus Torvalds * 181c1e8d7c6SMichel Lespinasse * This must be called with the mmap_lock held for reading. 182d9d332e0SLinus Torvalds */ 183d5a187daSVlastimil Babka int __anon_vma_prepare(struct vm_area_struct *vma) 1841da177e4SLinus Torvalds { 185d5a187daSVlastimil Babka struct mm_struct *mm = vma->vm_mm; 186d5a187daSVlastimil Babka struct anon_vma *anon_vma, *allocated; 1875beb4930SRik van Riel struct anon_vma_chain *avc; 1881da177e4SLinus Torvalds 1891da177e4SLinus Torvalds might_sleep(); 1901da177e4SLinus Torvalds 191dd34739cSLinus Torvalds avc = anon_vma_chain_alloc(GFP_KERNEL); 1925beb4930SRik van Riel if (!avc) 1935beb4930SRik van Riel goto out_enomem; 1945beb4930SRik van Riel 1951da177e4SLinus Torvalds anon_vma = find_mergeable_anon_vma(vma); 1961da177e4SLinus Torvalds allocated = NULL; 197d9d332e0SLinus Torvalds if (!anon_vma) { 1981da177e4SLinus Torvalds anon_vma = anon_vma_alloc(); 1991da177e4SLinus Torvalds if (unlikely(!anon_vma)) 2005beb4930SRik van Riel goto out_enomem_free_avc; 2011da177e4SLinus Torvalds allocated = anon_vma; 2021da177e4SLinus Torvalds } 2031da177e4SLinus Torvalds 2044fc3f1d6SIngo Molnar anon_vma_lock_write(anon_vma); 2051da177e4SLinus Torvalds /* page_table_lock to protect against threads */ 2061da177e4SLinus Torvalds spin_lock(&mm->page_table_lock); 2071da177e4SLinus Torvalds if (likely(!vma->anon_vma)) { 2081da177e4SLinus Torvalds vma->anon_vma = anon_vma; 2096583a843SKautuk Consul anon_vma_chain_link(vma, avc, anon_vma); 2107a3ef208SKonstantin Khlebnikov /* vma reference or self-parent link for new root */ 2117a3ef208SKonstantin Khlebnikov anon_vma->degree++; 2121da177e4SLinus Torvalds allocated = NULL; 21331f2b0ebSOleg Nesterov avc = NULL; 2141da177e4SLinus Torvalds } 2151da177e4SLinus Torvalds spin_unlock(&mm->page_table_lock); 21608b52706SKonstantin Khlebnikov anon_vma_unlock_write(anon_vma); 21731f2b0ebSOleg Nesterov 21831f2b0ebSOleg Nesterov if (unlikely(allocated)) 21901d8b20dSPeter Zijlstra put_anon_vma(allocated); 22031f2b0ebSOleg Nesterov if (unlikely(avc)) 2215beb4930SRik van Riel anon_vma_chain_free(avc); 222d5a187daSVlastimil Babka 2231da177e4SLinus Torvalds return 0; 2245beb4930SRik van Riel 2255beb4930SRik van Riel out_enomem_free_avc: 2265beb4930SRik van Riel anon_vma_chain_free(avc); 2275beb4930SRik van Riel out_enomem: 2285beb4930SRik van Riel return -ENOMEM; 2291da177e4SLinus Torvalds } 2301da177e4SLinus Torvalds 231bb4aa396SLinus Torvalds /* 232bb4aa396SLinus Torvalds * This is a useful helper function for locking the anon_vma root as 233bb4aa396SLinus Torvalds * we traverse the vma->anon_vma_chain, looping over anon_vma's that 234bb4aa396SLinus Torvalds * have the same vma. 235bb4aa396SLinus Torvalds * 236bb4aa396SLinus Torvalds * Such anon_vma's should have the same root, so you'd expect to see 237bb4aa396SLinus Torvalds * just a single mutex_lock for the whole traversal. 238bb4aa396SLinus Torvalds */ 239bb4aa396SLinus Torvalds static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma) 240bb4aa396SLinus Torvalds { 241bb4aa396SLinus Torvalds struct anon_vma *new_root = anon_vma->root; 242bb4aa396SLinus Torvalds if (new_root != root) { 243bb4aa396SLinus Torvalds if (WARN_ON_ONCE(root)) 2445a505085SIngo Molnar up_write(&root->rwsem); 245bb4aa396SLinus Torvalds root = new_root; 2465a505085SIngo Molnar down_write(&root->rwsem); 247bb4aa396SLinus Torvalds } 248bb4aa396SLinus Torvalds return root; 249bb4aa396SLinus Torvalds } 250bb4aa396SLinus Torvalds 251bb4aa396SLinus Torvalds static inline void unlock_anon_vma_root(struct anon_vma *root) 252bb4aa396SLinus Torvalds { 253bb4aa396SLinus Torvalds if (root) 2545a505085SIngo Molnar up_write(&root->rwsem); 255bb4aa396SLinus Torvalds } 256bb4aa396SLinus Torvalds 2575beb4930SRik van Riel /* 2585beb4930SRik van Riel * Attach the anon_vmas from src to dst. 2595beb4930SRik van Riel * Returns 0 on success, -ENOMEM on failure. 2607a3ef208SKonstantin Khlebnikov * 261cb152a1aSShijie Luo * anon_vma_clone() is called by __vma_adjust(), __split_vma(), copy_vma() and 26247b390d2SWei Yang * anon_vma_fork(). The first three want an exact copy of src, while the last 26347b390d2SWei Yang * one, anon_vma_fork(), may try to reuse an existing anon_vma to prevent 26447b390d2SWei Yang * endless growth of anon_vma. Since dst->anon_vma is set to NULL before call, 26547b390d2SWei Yang * we can identify this case by checking (!dst->anon_vma && src->anon_vma). 26647b390d2SWei Yang * 26747b390d2SWei Yang * If (!dst->anon_vma && src->anon_vma) is true, this function tries to find 26847b390d2SWei Yang * and reuse existing anon_vma which has no vmas and only one child anon_vma. 26947b390d2SWei Yang * This prevents degradation of anon_vma hierarchy to endless linear chain in 27047b390d2SWei Yang * case of constantly forking task. On the other hand, an anon_vma with more 27147b390d2SWei Yang * than one child isn't reused even if there was no alive vma, thus rmap 27247b390d2SWei Yang * walker has a good chance of avoiding scanning the whole hierarchy when it 27347b390d2SWei Yang * searches where page is mapped. 2745beb4930SRik van Riel */ 2755beb4930SRik van Riel int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) 2765beb4930SRik van Riel { 2775beb4930SRik van Riel struct anon_vma_chain *avc, *pavc; 278bb4aa396SLinus Torvalds struct anon_vma *root = NULL; 2795beb4930SRik van Riel 280646d87b4SLinus Torvalds list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { 281bb4aa396SLinus Torvalds struct anon_vma *anon_vma; 282bb4aa396SLinus Torvalds 283dd34739cSLinus Torvalds avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN); 284dd34739cSLinus Torvalds if (unlikely(!avc)) { 285dd34739cSLinus Torvalds unlock_anon_vma_root(root); 286dd34739cSLinus Torvalds root = NULL; 287dd34739cSLinus Torvalds avc = anon_vma_chain_alloc(GFP_KERNEL); 2885beb4930SRik van Riel if (!avc) 2895beb4930SRik van Riel goto enomem_failure; 290dd34739cSLinus Torvalds } 291bb4aa396SLinus Torvalds anon_vma = pavc->anon_vma; 292bb4aa396SLinus Torvalds root = lock_anon_vma_root(root, anon_vma); 293bb4aa396SLinus Torvalds anon_vma_chain_link(dst, avc, anon_vma); 2947a3ef208SKonstantin Khlebnikov 2957a3ef208SKonstantin Khlebnikov /* 2967a3ef208SKonstantin Khlebnikov * Reuse existing anon_vma if its degree lower than two, 2977a3ef208SKonstantin Khlebnikov * that means it has no vma and only one anon_vma child. 2987a3ef208SKonstantin Khlebnikov * 2997a3ef208SKonstantin Khlebnikov * Do not chose parent anon_vma, otherwise first child 3007a3ef208SKonstantin Khlebnikov * will always reuse it. Root anon_vma is never reused: 3017a3ef208SKonstantin Khlebnikov * it has self-parent reference and at least one child. 3027a3ef208SKonstantin Khlebnikov */ 30347b390d2SWei Yang if (!dst->anon_vma && src->anon_vma && 30447b390d2SWei Yang anon_vma != src->anon_vma && anon_vma->degree < 2) 3057a3ef208SKonstantin Khlebnikov dst->anon_vma = anon_vma; 3065beb4930SRik van Riel } 3077a3ef208SKonstantin Khlebnikov if (dst->anon_vma) 3087a3ef208SKonstantin Khlebnikov dst->anon_vma->degree++; 309bb4aa396SLinus Torvalds unlock_anon_vma_root(root); 3105beb4930SRik van Riel return 0; 3115beb4930SRik van Riel 3125beb4930SRik van Riel enomem_failure: 3133fe89b3eSLeon Yu /* 3143fe89b3eSLeon Yu * dst->anon_vma is dropped here otherwise its degree can be incorrectly 3153fe89b3eSLeon Yu * decremented in unlink_anon_vmas(). 3163fe89b3eSLeon Yu * We can safely do this because callers of anon_vma_clone() don't care 3173fe89b3eSLeon Yu * about dst->anon_vma if anon_vma_clone() failed. 3183fe89b3eSLeon Yu */ 3193fe89b3eSLeon Yu dst->anon_vma = NULL; 3205beb4930SRik van Riel unlink_anon_vmas(dst); 3215beb4930SRik van Riel return -ENOMEM; 3221da177e4SLinus Torvalds } 3231da177e4SLinus Torvalds 3245beb4930SRik van Riel /* 3255beb4930SRik van Riel * Attach vma to its own anon_vma, as well as to the anon_vmas that 3265beb4930SRik van Riel * the corresponding VMA in the parent process is attached to. 3275beb4930SRik van Riel * Returns 0 on success, non-zero on failure. 3285beb4930SRik van Riel */ 3295beb4930SRik van Riel int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) 3301da177e4SLinus Torvalds { 3315beb4930SRik van Riel struct anon_vma_chain *avc; 3325beb4930SRik van Riel struct anon_vma *anon_vma; 333c4ea95d7SDaniel Forrest int error; 3345beb4930SRik van Riel 3355beb4930SRik van Riel /* Don't bother if the parent process has no anon_vma here. */ 3365beb4930SRik van Riel if (!pvma->anon_vma) 3375beb4930SRik van Riel return 0; 3385beb4930SRik van Riel 3397a3ef208SKonstantin Khlebnikov /* Drop inherited anon_vma, we'll reuse existing or allocate new. */ 3407a3ef208SKonstantin Khlebnikov vma->anon_vma = NULL; 3417a3ef208SKonstantin Khlebnikov 3425beb4930SRik van Riel /* 3435beb4930SRik van Riel * First, attach the new VMA to the parent VMA's anon_vmas, 3445beb4930SRik van Riel * so rmap can find non-COWed pages in child processes. 3455beb4930SRik van Riel */ 346c4ea95d7SDaniel Forrest error = anon_vma_clone(vma, pvma); 347c4ea95d7SDaniel Forrest if (error) 348c4ea95d7SDaniel Forrest return error; 3495beb4930SRik van Riel 3507a3ef208SKonstantin Khlebnikov /* An existing anon_vma has been reused, all done then. */ 3517a3ef208SKonstantin Khlebnikov if (vma->anon_vma) 3527a3ef208SKonstantin Khlebnikov return 0; 3537a3ef208SKonstantin Khlebnikov 3545beb4930SRik van Riel /* Then add our own anon_vma. */ 3555beb4930SRik van Riel anon_vma = anon_vma_alloc(); 3565beb4930SRik van Riel if (!anon_vma) 3575beb4930SRik van Riel goto out_error; 358dd34739cSLinus Torvalds avc = anon_vma_chain_alloc(GFP_KERNEL); 3595beb4930SRik van Riel if (!avc) 3605beb4930SRik van Riel goto out_error_free_anon_vma; 3615c341ee1SRik van Riel 3625c341ee1SRik van Riel /* 363aaf1f990SMiaohe Lin * The root anon_vma's rwsem is the lock actually used when we 3645c341ee1SRik van Riel * lock any of the anon_vmas in this anon_vma tree. 3655c341ee1SRik van Riel */ 3665c341ee1SRik van Riel anon_vma->root = pvma->anon_vma->root; 3677a3ef208SKonstantin Khlebnikov anon_vma->parent = pvma->anon_vma; 36876545066SRik van Riel /* 36901d8b20dSPeter Zijlstra * With refcounts, an anon_vma can stay around longer than the 37001d8b20dSPeter Zijlstra * process it belongs to. The root anon_vma needs to be pinned until 37101d8b20dSPeter Zijlstra * this anon_vma is freed, because the lock lives in the root. 37276545066SRik van Riel */ 37376545066SRik van Riel get_anon_vma(anon_vma->root); 3745beb4930SRik van Riel /* Mark this anon_vma as the one where our new (COWed) pages go. */ 3755beb4930SRik van Riel vma->anon_vma = anon_vma; 3764fc3f1d6SIngo Molnar anon_vma_lock_write(anon_vma); 3775c341ee1SRik van Riel anon_vma_chain_link(vma, avc, anon_vma); 3787a3ef208SKonstantin Khlebnikov anon_vma->parent->degree++; 37908b52706SKonstantin Khlebnikov anon_vma_unlock_write(anon_vma); 3805beb4930SRik van Riel 3815beb4930SRik van Riel return 0; 3825beb4930SRik van Riel 3835beb4930SRik van Riel out_error_free_anon_vma: 38401d8b20dSPeter Zijlstra put_anon_vma(anon_vma); 3855beb4930SRik van Riel out_error: 3864946d54cSRik van Riel unlink_anon_vmas(vma); 3875beb4930SRik van Riel return -ENOMEM; 3885beb4930SRik van Riel } 3895beb4930SRik van Riel 3905beb4930SRik van Riel void unlink_anon_vmas(struct vm_area_struct *vma) 3915beb4930SRik van Riel { 3925beb4930SRik van Riel struct anon_vma_chain *avc, *next; 393eee2acbaSPeter Zijlstra struct anon_vma *root = NULL; 3945beb4930SRik van Riel 3955c341ee1SRik van Riel /* 3965c341ee1SRik van Riel * Unlink each anon_vma chained to the VMA. This list is ordered 3975c341ee1SRik van Riel * from newest to oldest, ensuring the root anon_vma gets freed last. 3985c341ee1SRik van Riel */ 3995beb4930SRik van Riel list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { 400eee2acbaSPeter Zijlstra struct anon_vma *anon_vma = avc->anon_vma; 401eee2acbaSPeter Zijlstra 402eee2acbaSPeter Zijlstra root = lock_anon_vma_root(root, anon_vma); 403bf181b9fSMichel Lespinasse anon_vma_interval_tree_remove(avc, &anon_vma->rb_root); 404eee2acbaSPeter Zijlstra 405eee2acbaSPeter Zijlstra /* 406eee2acbaSPeter Zijlstra * Leave empty anon_vmas on the list - we'll need 407eee2acbaSPeter Zijlstra * to free them outside the lock. 408eee2acbaSPeter Zijlstra */ 409f808c13fSDavidlohr Bueso if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) { 4107a3ef208SKonstantin Khlebnikov anon_vma->parent->degree--; 411eee2acbaSPeter Zijlstra continue; 4127a3ef208SKonstantin Khlebnikov } 413eee2acbaSPeter Zijlstra 414eee2acbaSPeter Zijlstra list_del(&avc->same_vma); 415eee2acbaSPeter Zijlstra anon_vma_chain_free(avc); 416eee2acbaSPeter Zijlstra } 417ee8ab190SLi Xinhai if (vma->anon_vma) { 4187a3ef208SKonstantin Khlebnikov vma->anon_vma->degree--; 419ee8ab190SLi Xinhai 420ee8ab190SLi Xinhai /* 421ee8ab190SLi Xinhai * vma would still be needed after unlink, and anon_vma will be prepared 422ee8ab190SLi Xinhai * when handle fault. 423ee8ab190SLi Xinhai */ 424ee8ab190SLi Xinhai vma->anon_vma = NULL; 425ee8ab190SLi Xinhai } 426eee2acbaSPeter Zijlstra unlock_anon_vma_root(root); 427eee2acbaSPeter Zijlstra 428eee2acbaSPeter Zijlstra /* 429eee2acbaSPeter Zijlstra * Iterate the list once more, it now only contains empty and unlinked 430eee2acbaSPeter Zijlstra * anon_vmas, destroy them. Could not do before due to __put_anon_vma() 4315a505085SIngo Molnar * needing to write-acquire the anon_vma->root->rwsem. 432eee2acbaSPeter Zijlstra */ 433eee2acbaSPeter Zijlstra list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { 434eee2acbaSPeter Zijlstra struct anon_vma *anon_vma = avc->anon_vma; 435eee2acbaSPeter Zijlstra 436e4c5800aSKonstantin Khlebnikov VM_WARN_ON(anon_vma->degree); 437eee2acbaSPeter Zijlstra put_anon_vma(anon_vma); 438eee2acbaSPeter Zijlstra 4395beb4930SRik van Riel list_del(&avc->same_vma); 4405beb4930SRik van Riel anon_vma_chain_free(avc); 4415beb4930SRik van Riel } 4425beb4930SRik van Riel } 4435beb4930SRik van Riel 44451cc5068SAlexey Dobriyan static void anon_vma_ctor(void *data) 4451da177e4SLinus Torvalds { 4461da177e4SLinus Torvalds struct anon_vma *anon_vma = data; 4471da177e4SLinus Torvalds 4485a505085SIngo Molnar init_rwsem(&anon_vma->rwsem); 44983813267SPeter Zijlstra atomic_set(&anon_vma->refcount, 0); 450f808c13fSDavidlohr Bueso anon_vma->rb_root = RB_ROOT_CACHED; 4511da177e4SLinus Torvalds } 4521da177e4SLinus Torvalds 4531da177e4SLinus Torvalds void __init anon_vma_init(void) 4541da177e4SLinus Torvalds { 4551da177e4SLinus Torvalds anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), 4565f0d5a3aSPaul E. McKenney 0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT, 4575d097056SVladimir Davydov anon_vma_ctor); 4585d097056SVladimir Davydov anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, 4595d097056SVladimir Davydov SLAB_PANIC|SLAB_ACCOUNT); 4601da177e4SLinus Torvalds } 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds /* 4636111e4caSPeter Zijlstra * Getting a lock on a stable anon_vma from a page off the LRU is tricky! 4646111e4caSPeter Zijlstra * 4656111e4caSPeter Zijlstra * Since there is no serialization what so ever against page_remove_rmap() 466ad8a20cfSMiaohe Lin * the best this function can do is return a refcount increased anon_vma 467ad8a20cfSMiaohe Lin * that might have been relevant to this page. 4686111e4caSPeter Zijlstra * 4696111e4caSPeter Zijlstra * The page might have been remapped to a different anon_vma or the anon_vma 4706111e4caSPeter Zijlstra * returned may already be freed (and even reused). 4716111e4caSPeter Zijlstra * 472bc658c96SPeter Zijlstra * In case it was remapped to a different anon_vma, the new anon_vma will be a 473bc658c96SPeter Zijlstra * child of the old anon_vma, and the anon_vma lifetime rules will therefore 474bc658c96SPeter Zijlstra * ensure that any anon_vma obtained from the page will still be valid for as 475bc658c96SPeter Zijlstra * long as we observe page_mapped() [ hence all those page_mapped() tests ]. 476bc658c96SPeter Zijlstra * 4776111e4caSPeter Zijlstra * All users of this function must be very careful when walking the anon_vma 4786111e4caSPeter Zijlstra * chain and verify that the page in question is indeed mapped in it 4796111e4caSPeter Zijlstra * [ something equivalent to page_mapped_in_vma() ]. 4806111e4caSPeter Zijlstra * 481091e4299SMiles Chen * Since anon_vma's slab is SLAB_TYPESAFE_BY_RCU and we know from 482091e4299SMiles Chen * page_remove_rmap() that the anon_vma pointer from page->mapping is valid 483091e4299SMiles Chen * if there is a mapcount, we can dereference the anon_vma after observing 484091e4299SMiles Chen * those. 4851da177e4SLinus Torvalds */ 486746b18d4SPeter Zijlstra struct anon_vma *page_get_anon_vma(struct page *page) 4871da177e4SLinus Torvalds { 488746b18d4SPeter Zijlstra struct anon_vma *anon_vma = NULL; 4891da177e4SLinus Torvalds unsigned long anon_mapping; 4901da177e4SLinus Torvalds 4911da177e4SLinus Torvalds rcu_read_lock(); 4924db0c3c2SJason Low anon_mapping = (unsigned long)READ_ONCE(page->mapping); 4933ca7b3c5SHugh Dickins if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) 4941da177e4SLinus Torvalds goto out; 4951da177e4SLinus Torvalds if (!page_mapped(page)) 4961da177e4SLinus Torvalds goto out; 4971da177e4SLinus Torvalds 4981da177e4SLinus Torvalds anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); 499746b18d4SPeter Zijlstra if (!atomic_inc_not_zero(&anon_vma->refcount)) { 500746b18d4SPeter Zijlstra anon_vma = NULL; 501746b18d4SPeter Zijlstra goto out; 502746b18d4SPeter Zijlstra } 503f1819427SHugh Dickins 504f1819427SHugh Dickins /* 505f1819427SHugh Dickins * If this page is still mapped, then its anon_vma cannot have been 506746b18d4SPeter Zijlstra * freed. But if it has been unmapped, we have no security against the 507746b18d4SPeter Zijlstra * anon_vma structure being freed and reused (for another anon_vma: 5085f0d5a3aSPaul E. McKenney * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero() 509746b18d4SPeter Zijlstra * above cannot corrupt). 510f1819427SHugh Dickins */ 511746b18d4SPeter Zijlstra if (!page_mapped(page)) { 5127f39dda9SHugh Dickins rcu_read_unlock(); 513746b18d4SPeter Zijlstra put_anon_vma(anon_vma); 5147f39dda9SHugh Dickins return NULL; 515746b18d4SPeter Zijlstra } 5161da177e4SLinus Torvalds out: 5171da177e4SLinus Torvalds rcu_read_unlock(); 518746b18d4SPeter Zijlstra 519746b18d4SPeter Zijlstra return anon_vma; 520746b18d4SPeter Zijlstra } 521746b18d4SPeter Zijlstra 52288c22088SPeter Zijlstra /* 52388c22088SPeter Zijlstra * Similar to page_get_anon_vma() except it locks the anon_vma. 52488c22088SPeter Zijlstra * 52588c22088SPeter Zijlstra * Its a little more complex as it tries to keep the fast path to a single 52688c22088SPeter Zijlstra * atomic op -- the trylock. If we fail the trylock, we fall back to getting a 52788c22088SPeter Zijlstra * reference like with page_get_anon_vma() and then block on the mutex. 52888c22088SPeter Zijlstra */ 5294fc3f1d6SIngo Molnar struct anon_vma *page_lock_anon_vma_read(struct page *page) 530746b18d4SPeter Zijlstra { 53188c22088SPeter Zijlstra struct anon_vma *anon_vma = NULL; 532eee0f252SHugh Dickins struct anon_vma *root_anon_vma; 53388c22088SPeter Zijlstra unsigned long anon_mapping; 534746b18d4SPeter Zijlstra 53588c22088SPeter Zijlstra rcu_read_lock(); 5364db0c3c2SJason Low anon_mapping = (unsigned long)READ_ONCE(page->mapping); 53788c22088SPeter Zijlstra if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) 53888c22088SPeter Zijlstra goto out; 53988c22088SPeter Zijlstra if (!page_mapped(page)) 54088c22088SPeter Zijlstra goto out; 54188c22088SPeter Zijlstra 54288c22088SPeter Zijlstra anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); 5434db0c3c2SJason Low root_anon_vma = READ_ONCE(anon_vma->root); 5444fc3f1d6SIngo Molnar if (down_read_trylock(&root_anon_vma->rwsem)) { 54588c22088SPeter Zijlstra /* 546eee0f252SHugh Dickins * If the page is still mapped, then this anon_vma is still 547eee0f252SHugh Dickins * its anon_vma, and holding the mutex ensures that it will 548bc658c96SPeter Zijlstra * not go away, see anon_vma_free(). 54988c22088SPeter Zijlstra */ 550eee0f252SHugh Dickins if (!page_mapped(page)) { 5514fc3f1d6SIngo Molnar up_read(&root_anon_vma->rwsem); 55288c22088SPeter Zijlstra anon_vma = NULL; 55388c22088SPeter Zijlstra } 55488c22088SPeter Zijlstra goto out; 55588c22088SPeter Zijlstra } 55688c22088SPeter Zijlstra 55788c22088SPeter Zijlstra /* trylock failed, we got to sleep */ 55888c22088SPeter Zijlstra if (!atomic_inc_not_zero(&anon_vma->refcount)) { 55988c22088SPeter Zijlstra anon_vma = NULL; 56088c22088SPeter Zijlstra goto out; 56188c22088SPeter Zijlstra } 56288c22088SPeter Zijlstra 56388c22088SPeter Zijlstra if (!page_mapped(page)) { 5647f39dda9SHugh Dickins rcu_read_unlock(); 56588c22088SPeter Zijlstra put_anon_vma(anon_vma); 5667f39dda9SHugh Dickins return NULL; 56788c22088SPeter Zijlstra } 56888c22088SPeter Zijlstra 56988c22088SPeter Zijlstra /* we pinned the anon_vma, its safe to sleep */ 57088c22088SPeter Zijlstra rcu_read_unlock(); 5714fc3f1d6SIngo Molnar anon_vma_lock_read(anon_vma); 572746b18d4SPeter Zijlstra 57388c22088SPeter Zijlstra if (atomic_dec_and_test(&anon_vma->refcount)) { 57488c22088SPeter Zijlstra /* 57588c22088SPeter Zijlstra * Oops, we held the last refcount, release the lock 57688c22088SPeter Zijlstra * and bail -- can't simply use put_anon_vma() because 5774fc3f1d6SIngo Molnar * we'll deadlock on the anon_vma_lock_write() recursion. 57888c22088SPeter Zijlstra */ 5794fc3f1d6SIngo Molnar anon_vma_unlock_read(anon_vma); 58088c22088SPeter Zijlstra __put_anon_vma(anon_vma); 58188c22088SPeter Zijlstra anon_vma = NULL; 58288c22088SPeter Zijlstra } 58388c22088SPeter Zijlstra 58488c22088SPeter Zijlstra return anon_vma; 58588c22088SPeter Zijlstra 58688c22088SPeter Zijlstra out: 58788c22088SPeter Zijlstra rcu_read_unlock(); 588746b18d4SPeter Zijlstra return anon_vma; 58934bbd704SOleg Nesterov } 59034bbd704SOleg Nesterov 5914fc3f1d6SIngo Molnar void page_unlock_anon_vma_read(struct anon_vma *anon_vma) 59234bbd704SOleg Nesterov { 5934fc3f1d6SIngo Molnar anon_vma_unlock_read(anon_vma); 5941da177e4SLinus Torvalds } 5951da177e4SLinus Torvalds 59672b252aeSMel Gorman #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 59772b252aeSMel Gorman /* 59872b252aeSMel Gorman * Flush TLB entries for recently unmapped pages from remote CPUs. It is 59972b252aeSMel Gorman * important if a PTE was dirty when it was unmapped that it's flushed 60072b252aeSMel Gorman * before any IO is initiated on the page to prevent lost writes. Similarly, 60172b252aeSMel Gorman * it must be flushed before freeing to prevent data leakage. 60272b252aeSMel Gorman */ 60372b252aeSMel Gorman void try_to_unmap_flush(void) 60472b252aeSMel Gorman { 60572b252aeSMel Gorman struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; 60672b252aeSMel Gorman 60772b252aeSMel Gorman if (!tlb_ubc->flush_required) 60872b252aeSMel Gorman return; 60972b252aeSMel Gorman 610e73ad5ffSAndy Lutomirski arch_tlbbatch_flush(&tlb_ubc->arch); 61172b252aeSMel Gorman tlb_ubc->flush_required = false; 612d950c947SMel Gorman tlb_ubc->writable = false; 61372b252aeSMel Gorman } 61472b252aeSMel Gorman 615d950c947SMel Gorman /* Flush iff there are potentially writable TLB entries that can race with IO */ 616d950c947SMel Gorman void try_to_unmap_flush_dirty(void) 617d950c947SMel Gorman { 618d950c947SMel Gorman struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; 619d950c947SMel Gorman 620d950c947SMel Gorman if (tlb_ubc->writable) 621d950c947SMel Gorman try_to_unmap_flush(); 622d950c947SMel Gorman } 623d950c947SMel Gorman 624*5ee2fa2fSHuang Ying /* 625*5ee2fa2fSHuang Ying * Bits 0-14 of mm->tlb_flush_batched record pending generations. 626*5ee2fa2fSHuang Ying * Bits 16-30 of mm->tlb_flush_batched bit record flushed generations. 627*5ee2fa2fSHuang Ying */ 628*5ee2fa2fSHuang Ying #define TLB_FLUSH_BATCH_FLUSHED_SHIFT 16 629*5ee2fa2fSHuang Ying #define TLB_FLUSH_BATCH_PENDING_MASK \ 630*5ee2fa2fSHuang Ying ((1 << (TLB_FLUSH_BATCH_FLUSHED_SHIFT - 1)) - 1) 631*5ee2fa2fSHuang Ying #define TLB_FLUSH_BATCH_PENDING_LARGE \ 632*5ee2fa2fSHuang Ying (TLB_FLUSH_BATCH_PENDING_MASK / 2) 633*5ee2fa2fSHuang Ying 634c7ab0d2fSKirill A. Shutemov static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) 63572b252aeSMel Gorman { 63672b252aeSMel Gorman struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; 637*5ee2fa2fSHuang Ying int batch, nbatch; 63872b252aeSMel Gorman 639e73ad5ffSAndy Lutomirski arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); 64072b252aeSMel Gorman tlb_ubc->flush_required = true; 641d950c947SMel Gorman 642d950c947SMel Gorman /* 6433ea27719SMel Gorman * Ensure compiler does not re-order the setting of tlb_flush_batched 6443ea27719SMel Gorman * before the PTE is cleared. 6453ea27719SMel Gorman */ 6463ea27719SMel Gorman barrier(); 647*5ee2fa2fSHuang Ying batch = atomic_read(&mm->tlb_flush_batched); 648*5ee2fa2fSHuang Ying retry: 649*5ee2fa2fSHuang Ying if ((batch & TLB_FLUSH_BATCH_PENDING_MASK) > TLB_FLUSH_BATCH_PENDING_LARGE) { 650*5ee2fa2fSHuang Ying /* 651*5ee2fa2fSHuang Ying * Prevent `pending' from catching up with `flushed' because of 652*5ee2fa2fSHuang Ying * overflow. Reset `pending' and `flushed' to be 1 and 0 if 653*5ee2fa2fSHuang Ying * `pending' becomes large. 654*5ee2fa2fSHuang Ying */ 655*5ee2fa2fSHuang Ying nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1); 656*5ee2fa2fSHuang Ying if (nbatch != batch) { 657*5ee2fa2fSHuang Ying batch = nbatch; 658*5ee2fa2fSHuang Ying goto retry; 659*5ee2fa2fSHuang Ying } 660*5ee2fa2fSHuang Ying } else { 661*5ee2fa2fSHuang Ying atomic_inc(&mm->tlb_flush_batched); 662*5ee2fa2fSHuang Ying } 6633ea27719SMel Gorman 6643ea27719SMel Gorman /* 665d950c947SMel Gorman * If the PTE was dirty then it's best to assume it's writable. The 666d950c947SMel Gorman * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush() 667d950c947SMel Gorman * before the page is queued for IO. 668d950c947SMel Gorman */ 669d950c947SMel Gorman if (writable) 670d950c947SMel Gorman tlb_ubc->writable = true; 67172b252aeSMel Gorman } 67272b252aeSMel Gorman 67372b252aeSMel Gorman /* 67472b252aeSMel Gorman * Returns true if the TLB flush should be deferred to the end of a batch of 67572b252aeSMel Gorman * unmap operations to reduce IPIs. 67672b252aeSMel Gorman */ 67772b252aeSMel Gorman static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) 67872b252aeSMel Gorman { 67972b252aeSMel Gorman bool should_defer = false; 68072b252aeSMel Gorman 68172b252aeSMel Gorman if (!(flags & TTU_BATCH_FLUSH)) 68272b252aeSMel Gorman return false; 68372b252aeSMel Gorman 68472b252aeSMel Gorman /* If remote CPUs need to be flushed then defer batch the flush */ 68572b252aeSMel Gorman if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) 68672b252aeSMel Gorman should_defer = true; 68772b252aeSMel Gorman put_cpu(); 68872b252aeSMel Gorman 68972b252aeSMel Gorman return should_defer; 69072b252aeSMel Gorman } 6913ea27719SMel Gorman 6923ea27719SMel Gorman /* 6933ea27719SMel Gorman * Reclaim unmaps pages under the PTL but do not flush the TLB prior to 6943ea27719SMel Gorman * releasing the PTL if TLB flushes are batched. It's possible for a parallel 6953ea27719SMel Gorman * operation such as mprotect or munmap to race between reclaim unmapping 6963ea27719SMel Gorman * the page and flushing the page. If this race occurs, it potentially allows 6973ea27719SMel Gorman * access to data via a stale TLB entry. Tracking all mm's that have TLB 6983ea27719SMel Gorman * batching in flight would be expensive during reclaim so instead track 6993ea27719SMel Gorman * whether TLB batching occurred in the past and if so then do a flush here 7003ea27719SMel Gorman * if required. This will cost one additional flush per reclaim cycle paid 7013ea27719SMel Gorman * by the first operation at risk such as mprotect and mumap. 7023ea27719SMel Gorman * 7033ea27719SMel Gorman * This must be called under the PTL so that an access to tlb_flush_batched 7043ea27719SMel Gorman * that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise 7053ea27719SMel Gorman * via the PTL. 7063ea27719SMel Gorman */ 7073ea27719SMel Gorman void flush_tlb_batched_pending(struct mm_struct *mm) 7083ea27719SMel Gorman { 709*5ee2fa2fSHuang Ying int batch = atomic_read(&mm->tlb_flush_batched); 710*5ee2fa2fSHuang Ying int pending = batch & TLB_FLUSH_BATCH_PENDING_MASK; 711*5ee2fa2fSHuang Ying int flushed = batch >> TLB_FLUSH_BATCH_FLUSHED_SHIFT; 7123ea27719SMel Gorman 713*5ee2fa2fSHuang Ying if (pending != flushed) { 714*5ee2fa2fSHuang Ying flush_tlb_mm(mm); 7153ea27719SMel Gorman /* 716*5ee2fa2fSHuang Ying * If the new TLB flushing is pending during flushing, leave 717*5ee2fa2fSHuang Ying * mm->tlb_flush_batched as is, to avoid losing flushing. 7183ea27719SMel Gorman */ 719*5ee2fa2fSHuang Ying atomic_cmpxchg(&mm->tlb_flush_batched, batch, 720*5ee2fa2fSHuang Ying pending | (pending << TLB_FLUSH_BATCH_FLUSHED_SHIFT)); 7213ea27719SMel Gorman } 7223ea27719SMel Gorman } 72372b252aeSMel Gorman #else 724c7ab0d2fSKirill A. Shutemov static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) 72572b252aeSMel Gorman { 72672b252aeSMel Gorman } 72772b252aeSMel Gorman 72872b252aeSMel Gorman static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) 72972b252aeSMel Gorman { 73072b252aeSMel Gorman return false; 73172b252aeSMel Gorman } 73272b252aeSMel Gorman #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */ 73372b252aeSMel Gorman 7341da177e4SLinus Torvalds /* 735bf89c8c8SHuang Shijie * At what user virtual address is page expected in vma? 736ab941e0fSNaoya Horiguchi * Caller should check the page is actually part of the vma. 7371da177e4SLinus Torvalds */ 7381da177e4SLinus Torvalds unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) 7391da177e4SLinus Torvalds { 74021d0d443SAndrea Arcangeli if (PageAnon(page)) { 7414829b906SHugh Dickins struct anon_vma *page__anon_vma = page_anon_vma(page); 7424829b906SHugh Dickins /* 7434829b906SHugh Dickins * Note: swapoff's unuse_vma() is more efficient with this 7444829b906SHugh Dickins * check, and needs it to match anon_vma when KSM is active. 7454829b906SHugh Dickins */ 7464829b906SHugh Dickins if (!vma->anon_vma || !page__anon_vma || 7474829b906SHugh Dickins vma->anon_vma->root != page__anon_vma->root) 74821d0d443SAndrea Arcangeli return -EFAULT; 74931657170SJue Wang } else if (!vma->vm_file) { 7501da177e4SLinus Torvalds return -EFAULT; 75131657170SJue Wang } else if (vma->vm_file->f_mapping != compound_head(page)->mapping) { 7521da177e4SLinus Torvalds return -EFAULT; 75331657170SJue Wang } 754494334e4SHugh Dickins 755494334e4SHugh Dickins return vma_address(page, vma); 7561da177e4SLinus Torvalds } 7571da177e4SLinus Torvalds 7586219049aSBob Liu pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) 7596219049aSBob Liu { 7606219049aSBob Liu pgd_t *pgd; 761c2febafcSKirill A. Shutemov p4d_t *p4d; 7626219049aSBob Liu pud_t *pud; 7636219049aSBob Liu pmd_t *pmd = NULL; 764f72e7dcdSHugh Dickins pmd_t pmde; 7656219049aSBob Liu 7666219049aSBob Liu pgd = pgd_offset(mm, address); 7676219049aSBob Liu if (!pgd_present(*pgd)) 7686219049aSBob Liu goto out; 7696219049aSBob Liu 770c2febafcSKirill A. Shutemov p4d = p4d_offset(pgd, address); 771c2febafcSKirill A. Shutemov if (!p4d_present(*p4d)) 772c2febafcSKirill A. Shutemov goto out; 773c2febafcSKirill A. Shutemov 774c2febafcSKirill A. Shutemov pud = pud_offset(p4d, address); 7756219049aSBob Liu if (!pud_present(*pud)) 7766219049aSBob Liu goto out; 7776219049aSBob Liu 7786219049aSBob Liu pmd = pmd_offset(pud, address); 779f72e7dcdSHugh Dickins /* 7808809aa2dSAneesh Kumar K.V * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at() 781f72e7dcdSHugh Dickins * without holding anon_vma lock for write. So when looking for a 782f72e7dcdSHugh Dickins * genuine pmde (in which to find pte), test present and !THP together. 783f72e7dcdSHugh Dickins */ 784e37c6982SChristian Borntraeger pmde = *pmd; 785e37c6982SChristian Borntraeger barrier(); 786f72e7dcdSHugh Dickins if (!pmd_present(pmde) || pmd_trans_huge(pmde)) 7876219049aSBob Liu pmd = NULL; 7886219049aSBob Liu out: 7896219049aSBob Liu return pmd; 7906219049aSBob Liu } 7916219049aSBob Liu 7929f32624bSJoonsoo Kim struct page_referenced_arg { 7939f32624bSJoonsoo Kim int mapcount; 7949f32624bSJoonsoo Kim int referenced; 7959f32624bSJoonsoo Kim unsigned long vm_flags; 7969f32624bSJoonsoo Kim struct mem_cgroup *memcg; 7979f32624bSJoonsoo Kim }; 79881b4082dSNikita Danilov /* 7999f32624bSJoonsoo Kim * arg: page_referenced_arg will be passed 8001da177e4SLinus Torvalds */ 801e4b82222SMinchan Kim static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, 8029f32624bSJoonsoo Kim unsigned long address, void *arg) 8031da177e4SLinus Torvalds { 8049f32624bSJoonsoo Kim struct page_referenced_arg *pra = arg; 8058eaededeSKirill A. Shutemov struct page_vma_mapped_walk pvmw = { 8068eaededeSKirill A. Shutemov .page = page, 8078eaededeSKirill A. Shutemov .vma = vma, 8088eaededeSKirill A. Shutemov .address = address, 8098eaededeSKirill A. Shutemov }; 8108749cfeaSVladimir Davydov int referenced = 0; 8112da28bfdSAndrea Arcangeli 8128eaededeSKirill A. Shutemov while (page_vma_mapped_walk(&pvmw)) { 8138eaededeSKirill A. Shutemov address = pvmw.address; 8142da28bfdSAndrea Arcangeli 815b20ce5e0SKirill A. Shutemov if (vma->vm_flags & VM_LOCKED) { 8168eaededeSKirill A. Shutemov page_vma_mapped_walk_done(&pvmw); 8179f32624bSJoonsoo Kim pra->vm_flags |= VM_LOCKED; 818e4b82222SMinchan Kim return false; /* To break the loop */ 8192da28bfdSAndrea Arcangeli } 8202da28bfdSAndrea Arcangeli 8218eaededeSKirill A. Shutemov if (pvmw.pte) { 8228eaededeSKirill A. Shutemov if (ptep_clear_flush_young_notify(vma, address, 8238eaededeSKirill A. Shutemov pvmw.pte)) { 8244917e5d0SJohannes Weiner /* 8258eaededeSKirill A. Shutemov * Don't treat a reference through 8268eaededeSKirill A. Shutemov * a sequentially read mapping as such. 8278eaededeSKirill A. Shutemov * If the page has been used in another mapping, 8288eaededeSKirill A. Shutemov * we will catch it; if this other mapping is 8298eaededeSKirill A. Shutemov * already gone, the unmap path will have set 8308eaededeSKirill A. Shutemov * PG_referenced or activated the page. 8314917e5d0SJohannes Weiner */ 83264363aadSJoe Perches if (likely(!(vma->vm_flags & VM_SEQ_READ))) 8331da177e4SLinus Torvalds referenced++; 8344917e5d0SJohannes Weiner } 8358749cfeaSVladimir Davydov } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { 8368eaededeSKirill A. Shutemov if (pmdp_clear_flush_young_notify(vma, address, 8378eaededeSKirill A. Shutemov pvmw.pmd)) 8388749cfeaSVladimir Davydov referenced++; 8398749cfeaSVladimir Davydov } else { 8408749cfeaSVladimir Davydov /* unexpected pmd-mapped page? */ 8418749cfeaSVladimir Davydov WARN_ON_ONCE(1); 8428749cfeaSVladimir Davydov } 8438eaededeSKirill A. Shutemov 8448eaededeSKirill A. Shutemov pra->mapcount--; 8458eaededeSKirill A. Shutemov } 84671e3aac0SAndrea Arcangeli 84733c3fc71SVladimir Davydov if (referenced) 84833c3fc71SVladimir Davydov clear_page_idle(page); 84933c3fc71SVladimir Davydov if (test_and_clear_page_young(page)) 85033c3fc71SVladimir Davydov referenced++; 85133c3fc71SVladimir Davydov 8529f32624bSJoonsoo Kim if (referenced) { 8539f32624bSJoonsoo Kim pra->referenced++; 8549f32624bSJoonsoo Kim pra->vm_flags |= vma->vm_flags; 8551da177e4SLinus Torvalds } 8561da177e4SLinus Torvalds 8579f32624bSJoonsoo Kim if (!pra->mapcount) 858e4b82222SMinchan Kim return false; /* To break the loop */ 8599f32624bSJoonsoo Kim 860e4b82222SMinchan Kim return true; 8619f32624bSJoonsoo Kim } 8629f32624bSJoonsoo Kim 8639f32624bSJoonsoo Kim static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) 8641da177e4SLinus Torvalds { 8659f32624bSJoonsoo Kim struct page_referenced_arg *pra = arg; 8669f32624bSJoonsoo Kim struct mem_cgroup *memcg = pra->memcg; 8671da177e4SLinus Torvalds 8689f32624bSJoonsoo Kim if (!mm_match_cgroup(vma->vm_mm, memcg)) 8699f32624bSJoonsoo Kim return true; 8701da177e4SLinus Torvalds 8719f32624bSJoonsoo Kim return false; 8721da177e4SLinus Torvalds } 8731da177e4SLinus Torvalds 8741da177e4SLinus Torvalds /** 8751da177e4SLinus Torvalds * page_referenced - test if the page was referenced 8761da177e4SLinus Torvalds * @page: the page to test 8771da177e4SLinus Torvalds * @is_locked: caller holds lock on the page 87872835c86SJohannes Weiner * @memcg: target memory cgroup 8796fe6b7e3SWu Fengguang * @vm_flags: collect encountered vma->vm_flags who actually referenced the page 8801da177e4SLinus Torvalds * 8811da177e4SLinus Torvalds * Quick test_and_clear_referenced for all mappings to a page, 8821da177e4SLinus Torvalds * returns the number of ptes which referenced the page. 8831da177e4SLinus Torvalds */ 8846fe6b7e3SWu Fengguang int page_referenced(struct page *page, 8856fe6b7e3SWu Fengguang int is_locked, 88672835c86SJohannes Weiner struct mem_cgroup *memcg, 8876fe6b7e3SWu Fengguang unsigned long *vm_flags) 8881da177e4SLinus Torvalds { 8895ad64688SHugh Dickins int we_locked = 0; 8909f32624bSJoonsoo Kim struct page_referenced_arg pra = { 891b20ce5e0SKirill A. Shutemov .mapcount = total_mapcount(page), 8929f32624bSJoonsoo Kim .memcg = memcg, 8939f32624bSJoonsoo Kim }; 8949f32624bSJoonsoo Kim struct rmap_walk_control rwc = { 8959f32624bSJoonsoo Kim .rmap_one = page_referenced_one, 8969f32624bSJoonsoo Kim .arg = (void *)&pra, 8979f32624bSJoonsoo Kim .anon_lock = page_lock_anon_vma_read, 8989f32624bSJoonsoo Kim }; 8991da177e4SLinus Torvalds 9006fe6b7e3SWu Fengguang *vm_flags = 0; 901059d8442SHuang Shijie if (!pra.mapcount) 9029f32624bSJoonsoo Kim return 0; 9039f32624bSJoonsoo Kim 9049f32624bSJoonsoo Kim if (!page_rmapping(page)) 9059f32624bSJoonsoo Kim return 0; 9069f32624bSJoonsoo Kim 9075ad64688SHugh Dickins if (!is_locked && (!PageAnon(page) || PageKsm(page))) { 9085ad64688SHugh Dickins we_locked = trylock_page(page); 9099f32624bSJoonsoo Kim if (!we_locked) 9109f32624bSJoonsoo Kim return 1; 9115ad64688SHugh Dickins } 9129f32624bSJoonsoo Kim 9139f32624bSJoonsoo Kim /* 9149f32624bSJoonsoo Kim * If we are reclaiming on behalf of a cgroup, skip 9159f32624bSJoonsoo Kim * counting on behalf of references from different 9169f32624bSJoonsoo Kim * cgroups 9179f32624bSJoonsoo Kim */ 9189f32624bSJoonsoo Kim if (memcg) { 9199f32624bSJoonsoo Kim rwc.invalid_vma = invalid_page_referenced_vma; 9205ad64688SHugh Dickins } 9219f32624bSJoonsoo Kim 922c24f386cSMinchan Kim rmap_walk(page, &rwc); 9239f32624bSJoonsoo Kim *vm_flags = pra.vm_flags; 9249f32624bSJoonsoo Kim 9255ad64688SHugh Dickins if (we_locked) 9261da177e4SLinus Torvalds unlock_page(page); 9279f32624bSJoonsoo Kim 9289f32624bSJoonsoo Kim return pra.referenced; 9291da177e4SLinus Torvalds } 9301da177e4SLinus Torvalds 931e4b82222SMinchan Kim static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, 9329853a407SJoonsoo Kim unsigned long address, void *arg) 933d08b3851SPeter Zijlstra { 934f27176cfSKirill A. Shutemov struct page_vma_mapped_walk pvmw = { 935f27176cfSKirill A. Shutemov .page = page, 936f27176cfSKirill A. Shutemov .vma = vma, 937f27176cfSKirill A. Shutemov .address = address, 938f27176cfSKirill A. Shutemov .flags = PVMW_SYNC, 939f27176cfSKirill A. Shutemov }; 940ac46d4f3SJérôme Glisse struct mmu_notifier_range range; 9419853a407SJoonsoo Kim int *cleaned = arg; 942d08b3851SPeter Zijlstra 943369ea824SJérôme Glisse /* 944369ea824SJérôme Glisse * We have to assume the worse case ie pmd for invalidation. Note that 945369ea824SJérôme Glisse * the page can not be free from this function. 946369ea824SJérôme Glisse */ 9477269f999SJérôme Glisse mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 9487269f999SJérôme Glisse 0, vma, vma->vm_mm, address, 949494334e4SHugh Dickins vma_address_end(page, vma)); 950ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_start(&range); 951369ea824SJérôme Glisse 952f27176cfSKirill A. Shutemov while (page_vma_mapped_walk(&pvmw)) { 953f27176cfSKirill A. Shutemov int ret = 0; 954369ea824SJérôme Glisse 9551f18b296SYueHaibing address = pvmw.address; 956f27176cfSKirill A. Shutemov if (pvmw.pte) { 957c2fda5feSPeter Zijlstra pte_t entry; 958f27176cfSKirill A. Shutemov pte_t *pte = pvmw.pte; 959f27176cfSKirill A. Shutemov 960f27176cfSKirill A. Shutemov if (!pte_dirty(*pte) && !pte_write(*pte)) 961f27176cfSKirill A. Shutemov continue; 962d08b3851SPeter Zijlstra 963785373b4SLinus Torvalds flush_cache_page(vma, address, pte_pfn(*pte)); 964785373b4SLinus Torvalds entry = ptep_clear_flush(vma, address, pte); 965d08b3851SPeter Zijlstra entry = pte_wrprotect(entry); 966c2fda5feSPeter Zijlstra entry = pte_mkclean(entry); 967785373b4SLinus Torvalds set_pte_at(vma->vm_mm, address, pte, entry); 968d08b3851SPeter Zijlstra ret = 1; 969f27176cfSKirill A. Shutemov } else { 970396bcc52SMatthew Wilcox (Oracle) #ifdef CONFIG_TRANSPARENT_HUGEPAGE 971f27176cfSKirill A. Shutemov pmd_t *pmd = pvmw.pmd; 972f27176cfSKirill A. Shutemov pmd_t entry; 973d08b3851SPeter Zijlstra 974f27176cfSKirill A. Shutemov if (!pmd_dirty(*pmd) && !pmd_write(*pmd)) 975f27176cfSKirill A. Shutemov continue; 976f27176cfSKirill A. Shutemov 977785373b4SLinus Torvalds flush_cache_page(vma, address, page_to_pfn(page)); 978024eee0eSAneesh Kumar K.V entry = pmdp_invalidate(vma, address, pmd); 979f27176cfSKirill A. Shutemov entry = pmd_wrprotect(entry); 980f27176cfSKirill A. Shutemov entry = pmd_mkclean(entry); 981785373b4SLinus Torvalds set_pmd_at(vma->vm_mm, address, pmd, entry); 982f27176cfSKirill A. Shutemov ret = 1; 983f27176cfSKirill A. Shutemov #else 984f27176cfSKirill A. Shutemov /* unexpected pmd-mapped page? */ 985f27176cfSKirill A. Shutemov WARN_ON_ONCE(1); 986f27176cfSKirill A. Shutemov #endif 987f27176cfSKirill A. Shutemov } 9882ec74c3eSSagi Grimberg 9890f10851eSJérôme Glisse /* 9900f10851eSJérôme Glisse * No need to call mmu_notifier_invalidate_range() as we are 9910f10851eSJérôme Glisse * downgrading page table protection not changing it to point 9920f10851eSJérôme Glisse * to a new page. 9930f10851eSJérôme Glisse * 994ad56b738SMike Rapoport * See Documentation/vm/mmu_notifier.rst 9950f10851eSJérôme Glisse */ 9960f10851eSJérôme Glisse if (ret) 9979853a407SJoonsoo Kim (*cleaned)++; 9989853a407SJoonsoo Kim } 999f27176cfSKirill A. Shutemov 1000ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_end(&range); 1001369ea824SJérôme Glisse 1002e4b82222SMinchan Kim return true; 1003d08b3851SPeter Zijlstra } 1004d08b3851SPeter Zijlstra 10059853a407SJoonsoo Kim static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg) 1006d08b3851SPeter Zijlstra { 10079853a407SJoonsoo Kim if (vma->vm_flags & VM_SHARED) 1008871beb8cSFengguang Wu return false; 1009d08b3851SPeter Zijlstra 1010871beb8cSFengguang Wu return true; 1011d08b3851SPeter Zijlstra } 1012d08b3851SPeter Zijlstra 1013d9c08e22SMatthew Wilcox (Oracle) int folio_mkclean(struct folio *folio) 1014d08b3851SPeter Zijlstra { 10159853a407SJoonsoo Kim int cleaned = 0; 10169853a407SJoonsoo Kim struct address_space *mapping; 10179853a407SJoonsoo Kim struct rmap_walk_control rwc = { 10189853a407SJoonsoo Kim .arg = (void *)&cleaned, 10199853a407SJoonsoo Kim .rmap_one = page_mkclean_one, 10209853a407SJoonsoo Kim .invalid_vma = invalid_mkclean_vma, 10219853a407SJoonsoo Kim }; 1022d08b3851SPeter Zijlstra 1023d9c08e22SMatthew Wilcox (Oracle) BUG_ON(!folio_test_locked(folio)); 1024d08b3851SPeter Zijlstra 1025d9c08e22SMatthew Wilcox (Oracle) if (!folio_mapped(folio)) 10269853a407SJoonsoo Kim return 0; 1027d08b3851SPeter Zijlstra 1028d9c08e22SMatthew Wilcox (Oracle) mapping = folio_mapping(folio); 10299853a407SJoonsoo Kim if (!mapping) 10309853a407SJoonsoo Kim return 0; 10319853a407SJoonsoo Kim 1032d9c08e22SMatthew Wilcox (Oracle) rmap_walk(&folio->page, &rwc); 10339853a407SJoonsoo Kim 10349853a407SJoonsoo Kim return cleaned; 1035d08b3851SPeter Zijlstra } 1036d9c08e22SMatthew Wilcox (Oracle) EXPORT_SYMBOL_GPL(folio_mkclean); 1037d08b3851SPeter Zijlstra 10381da177e4SLinus Torvalds /** 1039c44b6743SRik van Riel * page_move_anon_rmap - move a page to our anon_vma 1040c44b6743SRik van Riel * @page: the page to move to our anon_vma 1041c44b6743SRik van Riel * @vma: the vma the page belongs to 1042c44b6743SRik van Riel * 1043c44b6743SRik van Riel * When a page belongs exclusively to one process after a COW event, 1044c44b6743SRik van Riel * that page can be moved into the anon_vma that belongs to just that 1045c44b6743SRik van Riel * process, so the rmap code will not search the parent or sibling 1046c44b6743SRik van Riel * processes. 1047c44b6743SRik van Riel */ 10485a49973dSHugh Dickins void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma) 1049c44b6743SRik van Riel { 1050c44b6743SRik van Riel struct anon_vma *anon_vma = vma->anon_vma; 1051c44b6743SRik van Riel 10525a49973dSHugh Dickins page = compound_head(page); 10535a49973dSHugh Dickins 1054309381feSSasha Levin VM_BUG_ON_PAGE(!PageLocked(page), page); 105581d1b09cSSasha Levin VM_BUG_ON_VMA(!anon_vma, vma); 1056c44b6743SRik van Riel 1057c44b6743SRik van Riel anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; 1058414e2fb8SVladimir Davydov /* 1059414e2fb8SVladimir Davydov * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written 1060414e2fb8SVladimir Davydov * simultaneously, so a concurrent reader (eg page_referenced()'s 1061414e2fb8SVladimir Davydov * PageAnon()) will not see one without the other. 1062414e2fb8SVladimir Davydov */ 1063414e2fb8SVladimir Davydov WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); 1064c44b6743SRik van Riel } 1065c44b6743SRik van Riel 1066c44b6743SRik van Riel /** 106743d8eac4SRandy Dunlap * __page_set_anon_rmap - set up new anonymous rmap 1068451b9514SKirill Tkhai * @page: Page or Hugepage to add to rmap 10694e1c1975SAndi Kleen * @vma: VM area to add page to. 10704e1c1975SAndi Kleen * @address: User virtual address of the mapping 1071e8a03febSRik van Riel * @exclusive: the page is exclusively owned by the current process 10721da177e4SLinus Torvalds */ 10739617d95eSNick Piggin static void __page_set_anon_rmap(struct page *page, 1074e8a03febSRik van Riel struct vm_area_struct *vma, unsigned long address, int exclusive) 10751da177e4SLinus Torvalds { 1076e8a03febSRik van Riel struct anon_vma *anon_vma = vma->anon_vma; 10772822c1aaSNick Piggin 1078e8a03febSRik van Riel BUG_ON(!anon_vma); 1079ea90002bSLinus Torvalds 10804e1c1975SAndi Kleen if (PageAnon(page)) 10814e1c1975SAndi Kleen return; 10824e1c1975SAndi Kleen 1083ea90002bSLinus Torvalds /* 1084e8a03febSRik van Riel * If the page isn't exclusively mapped into this vma, 1085e8a03febSRik van Riel * we must use the _oldest_ possible anon_vma for the 1086e8a03febSRik van Riel * page mapping! 1087ea90002bSLinus Torvalds */ 10884e1c1975SAndi Kleen if (!exclusive) 1089288468c3SAndrea Arcangeli anon_vma = anon_vma->root; 1090ea90002bSLinus Torvalds 109116f5e707SAlex Shi /* 109216f5e707SAlex Shi * page_idle does a lockless/optimistic rmap scan on page->mapping. 109316f5e707SAlex Shi * Make sure the compiler doesn't split the stores of anon_vma and 109416f5e707SAlex Shi * the PAGE_MAPPING_ANON type identifier, otherwise the rmap code 109516f5e707SAlex Shi * could mistake the mapping for a struct address_space and crash. 109616f5e707SAlex Shi */ 10971da177e4SLinus Torvalds anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; 109816f5e707SAlex Shi WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); 10994d7670e0SNick Piggin page->index = linear_page_index(vma, address); 11001da177e4SLinus Torvalds } 11019617d95eSNick Piggin 11029617d95eSNick Piggin /** 110343d8eac4SRandy Dunlap * __page_check_anon_rmap - sanity check anonymous rmap addition 1104c97a9e10SNick Piggin * @page: the page to add the mapping to 1105c97a9e10SNick Piggin * @vma: the vm area in which the mapping is added 1106c97a9e10SNick Piggin * @address: the user virtual address mapped 1107c97a9e10SNick Piggin */ 1108c97a9e10SNick Piggin static void __page_check_anon_rmap(struct page *page, 1109c97a9e10SNick Piggin struct vm_area_struct *vma, unsigned long address) 1110c97a9e10SNick Piggin { 1111c97a9e10SNick Piggin /* 1112c97a9e10SNick Piggin * The page's anon-rmap details (mapping and index) are guaranteed to 1113c97a9e10SNick Piggin * be set up correctly at this point. 1114c97a9e10SNick Piggin * 1115c97a9e10SNick Piggin * We have exclusion against page_add_anon_rmap because the caller 111690aaca85SMiaohe Lin * always holds the page locked. 1117c97a9e10SNick Piggin * 1118c97a9e10SNick Piggin * We have exclusion against page_add_new_anon_rmap because those pages 1119c97a9e10SNick Piggin * are initially only visible via the pagetables, and the pte is locked 1120c97a9e10SNick Piggin * over the call to page_add_new_anon_rmap. 1121c97a9e10SNick Piggin */ 112230c46382SYang Shi VM_BUG_ON_PAGE(page_anon_vma(page)->root != vma->anon_vma->root, page); 112330c46382SYang Shi VM_BUG_ON_PAGE(page_to_pgoff(page) != linear_page_index(vma, address), 112430c46382SYang Shi page); 1125c97a9e10SNick Piggin } 1126c97a9e10SNick Piggin 1127c97a9e10SNick Piggin /** 11289617d95eSNick Piggin * page_add_anon_rmap - add pte mapping to an anonymous page 11299617d95eSNick Piggin * @page: the page to add the mapping to 11309617d95eSNick Piggin * @vma: the vm area in which the mapping is added 11319617d95eSNick Piggin * @address: the user virtual address mapped 1132d281ee61SKirill A. Shutemov * @compound: charge the page as compound or small page 11339617d95eSNick Piggin * 11345ad64688SHugh Dickins * The caller needs to hold the pte lock, and the page must be locked in 113580e14822SHugh Dickins * the anon_vma case: to serialize mapping,index checking after setting, 113680e14822SHugh Dickins * and to ensure that PageAnon is not being upgraded racily to PageKsm 113780e14822SHugh Dickins * (but PageKsm is never downgraded to PageAnon). 11389617d95eSNick Piggin */ 11399617d95eSNick Piggin void page_add_anon_rmap(struct page *page, 1140d281ee61SKirill A. Shutemov struct vm_area_struct *vma, unsigned long address, bool compound) 11419617d95eSNick Piggin { 1142d281ee61SKirill A. Shutemov do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0); 1143ad8c2ee8SRik van Riel } 1144ad8c2ee8SRik van Riel 1145ad8c2ee8SRik van Riel /* 1146ad8c2ee8SRik van Riel * Special version of the above for do_swap_page, which often runs 1147ad8c2ee8SRik van Riel * into pages that are exclusively owned by the current process. 1148ad8c2ee8SRik van Riel * Everybody else should continue to use page_add_anon_rmap above. 1149ad8c2ee8SRik van Riel */ 1150ad8c2ee8SRik van Riel void do_page_add_anon_rmap(struct page *page, 1151d281ee61SKirill A. Shutemov struct vm_area_struct *vma, unsigned long address, int flags) 1152ad8c2ee8SRik van Riel { 1153d281ee61SKirill A. Shutemov bool compound = flags & RMAP_COMPOUND; 115453f9263bSKirill A. Shutemov bool first; 115553f9263bSKirill A. Shutemov 1156be5d0a74SJohannes Weiner if (unlikely(PageKsm(page))) 1157be5d0a74SJohannes Weiner lock_page_memcg(page); 1158be5d0a74SJohannes Weiner else 1159be5d0a74SJohannes Weiner VM_BUG_ON_PAGE(!PageLocked(page), page); 1160be5d0a74SJohannes Weiner 116153f9263bSKirill A. Shutemov if (compound) { 116253f9263bSKirill A. Shutemov atomic_t *mapcount; 1163e9b61f19SKirill A. Shutemov VM_BUG_ON_PAGE(!PageLocked(page), page); 116453f9263bSKirill A. Shutemov VM_BUG_ON_PAGE(!PageTransHuge(page), page); 116553f9263bSKirill A. Shutemov mapcount = compound_mapcount_ptr(page); 116653f9263bSKirill A. Shutemov first = atomic_inc_and_test(mapcount); 116753f9263bSKirill A. Shutemov } else { 116853f9263bSKirill A. Shutemov first = atomic_inc_and_test(&page->_mapcount); 116953f9263bSKirill A. Shutemov } 117053f9263bSKirill A. Shutemov 117153f9263bSKirill A. Shutemov if (first) { 11726c357848SMatthew Wilcox (Oracle) int nr = compound ? thp_nr_pages(page) : 1; 1173bea04b07SJianyu Zhan /* 1174bea04b07SJianyu Zhan * We use the irq-unsafe __{inc|mod}_zone_page_stat because 1175bea04b07SJianyu Zhan * these counters are not modified in interrupt context, and 1176bea04b07SJianyu Zhan * pte lock(a spinlock) is held, which implies preemption 1177bea04b07SJianyu Zhan * disabled. 1178bea04b07SJianyu Zhan */ 117965c45377SKirill A. Shutemov if (compound) 118069473e5dSMuchun Song __mod_lruvec_page_state(page, NR_ANON_THPS, nr); 1181be5d0a74SJohannes Weiner __mod_lruvec_page_state(page, NR_ANON_MAPPED, nr); 118279134171SAndrea Arcangeli } 11835ad64688SHugh Dickins 1184be5d0a74SJohannes Weiner if (unlikely(PageKsm(page))) { 1185be5d0a74SJohannes Weiner unlock_page_memcg(page); 1186be5d0a74SJohannes Weiner return; 1187be5d0a74SJohannes Weiner } 118853f9263bSKirill A. Shutemov 11895dbe0af4SHugh Dickins /* address might be in next vma when migration races vma_adjust */ 11905ad64688SHugh Dickins if (first) 1191d281ee61SKirill A. Shutemov __page_set_anon_rmap(page, vma, address, 1192d281ee61SKirill A. Shutemov flags & RMAP_EXCLUSIVE); 119369029cd5SKAMEZAWA Hiroyuki else 1194c97a9e10SNick Piggin __page_check_anon_rmap(page, vma, address); 11951da177e4SLinus Torvalds } 11961da177e4SLinus Torvalds 119743d8eac4SRandy Dunlap /** 11989617d95eSNick Piggin * page_add_new_anon_rmap - add pte mapping to a new anonymous page 11999617d95eSNick Piggin * @page: the page to add the mapping to 12009617d95eSNick Piggin * @vma: the vm area in which the mapping is added 12019617d95eSNick Piggin * @address: the user virtual address mapped 1202d281ee61SKirill A. Shutemov * @compound: charge the page as compound or small page 12039617d95eSNick Piggin * 12049617d95eSNick Piggin * Same as page_add_anon_rmap but must only be called on *new* pages. 12059617d95eSNick Piggin * This means the inc-and-test can be bypassed. 1206c97a9e10SNick Piggin * Page does not have to be locked. 12079617d95eSNick Piggin */ 12089617d95eSNick Piggin void page_add_new_anon_rmap(struct page *page, 1209d281ee61SKirill A. Shutemov struct vm_area_struct *vma, unsigned long address, bool compound) 12109617d95eSNick Piggin { 12116c357848SMatthew Wilcox (Oracle) int nr = compound ? thp_nr_pages(page) : 1; 1212d281ee61SKirill A. Shutemov 121381d1b09cSSasha Levin VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); 1214fa9949daSHugh Dickins __SetPageSwapBacked(page); 1215d281ee61SKirill A. Shutemov if (compound) { 1216d281ee61SKirill A. Shutemov VM_BUG_ON_PAGE(!PageTransHuge(page), page); 121753f9263bSKirill A. Shutemov /* increment count (starts at -1) */ 121853f9263bSKirill A. Shutemov atomic_set(compound_mapcount_ptr(page), 0); 121947e29d32SJohn Hubbard if (hpage_pincount_available(page)) 122047e29d32SJohn Hubbard atomic_set(compound_pincount_ptr(page), 0); 122147e29d32SJohn Hubbard 122269473e5dSMuchun Song __mod_lruvec_page_state(page, NR_ANON_THPS, nr); 122353f9263bSKirill A. Shutemov } else { 122453f9263bSKirill A. Shutemov /* Anon THP always mapped first with PMD */ 122553f9263bSKirill A. Shutemov VM_BUG_ON_PAGE(PageTransCompound(page), page); 122653f9263bSKirill A. Shutemov /* increment count (starts at -1) */ 122753f9263bSKirill A. Shutemov atomic_set(&page->_mapcount, 0); 1228d281ee61SKirill A. Shutemov } 1229be5d0a74SJohannes Weiner __mod_lruvec_page_state(page, NR_ANON_MAPPED, nr); 1230e8a03febSRik van Riel __page_set_anon_rmap(page, vma, address, 1); 12319617d95eSNick Piggin } 12329617d95eSNick Piggin 12331da177e4SLinus Torvalds /** 12341da177e4SLinus Torvalds * page_add_file_rmap - add pte mapping to a file page 12351da177e4SLinus Torvalds * @page: the page to add the mapping to 1236e8b098fcSMike Rapoport * @compound: charge the page as compound or small page 12371da177e4SLinus Torvalds * 1238b8072f09SHugh Dickins * The caller needs to hold the pte lock. 12391da177e4SLinus Torvalds */ 1240dd78feddSKirill A. Shutemov void page_add_file_rmap(struct page *page, bool compound) 12411da177e4SLinus Torvalds { 1242dd78feddSKirill A. Shutemov int i, nr = 1; 1243dd78feddSKirill A. Shutemov 1244dd78feddSKirill A. Shutemov VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page); 124562cccb8cSJohannes Weiner lock_page_memcg(page); 1246dd78feddSKirill A. Shutemov if (compound && PageTransHuge(page)) { 1247a1528e21SMuchun Song int nr_pages = thp_nr_pages(page); 1248a1528e21SMuchun Song 1249a1528e21SMuchun Song for (i = 0, nr = 0; i < nr_pages; i++) { 1250dd78feddSKirill A. Shutemov if (atomic_inc_and_test(&page[i]._mapcount)) 1251dd78feddSKirill A. Shutemov nr++; 1252d69b042fSBalbir Singh } 1253dd78feddSKirill A. Shutemov if (!atomic_inc_and_test(compound_mapcount_ptr(page))) 1254dd78feddSKirill A. Shutemov goto out; 125599cb0dbdSSong Liu if (PageSwapBacked(page)) 1256a1528e21SMuchun Song __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, 1257a1528e21SMuchun Song nr_pages); 125899cb0dbdSSong Liu else 1259380780e7SMuchun Song __mod_lruvec_page_state(page, NR_FILE_PMDMAPPED, 1260380780e7SMuchun Song nr_pages); 1261dd78feddSKirill A. Shutemov } else { 1262c8efc390SKirill A. Shutemov if (PageTransCompound(page) && page_mapping(page)) { 1263fe3df441SMuchun Song struct page *head = compound_head(page); 1264fe3df441SMuchun Song 1265c8efc390SKirill A. Shutemov VM_WARN_ON_ONCE(!PageLocked(page)); 1266c8efc390SKirill A. Shutemov 1267fe3df441SMuchun Song SetPageDoubleMap(head); 12689a73f61bSKirill A. Shutemov if (PageMlocked(page)) 1269fe3df441SMuchun Song clear_page_mlock(head); 12709a73f61bSKirill A. Shutemov } 1271dd78feddSKirill A. Shutemov if (!atomic_inc_and_test(&page->_mapcount)) 1272dd78feddSKirill A. Shutemov goto out; 1273dd78feddSKirill A. Shutemov } 127400f3ca2cSJohannes Weiner __mod_lruvec_page_state(page, NR_FILE_MAPPED, nr); 1275dd78feddSKirill A. Shutemov out: 127662cccb8cSJohannes Weiner unlock_page_memcg(page); 12771da177e4SLinus Torvalds } 12781da177e4SLinus Torvalds 1279dd78feddSKirill A. Shutemov static void page_remove_file_rmap(struct page *page, bool compound) 12808186eb6aSJohannes Weiner { 1281dd78feddSKirill A. Shutemov int i, nr = 1; 1282dd78feddSKirill A. Shutemov 128357dea93aSSteve Capper VM_BUG_ON_PAGE(compound && !PageHead(page), page); 12848186eb6aSJohannes Weiner 128553f9263bSKirill A. Shutemov /* Hugepages are not counted in NR_FILE_MAPPED for now. */ 128653f9263bSKirill A. Shutemov if (unlikely(PageHuge(page))) { 128753f9263bSKirill A. Shutemov /* hugetlb pages are always mapped with pmds */ 128853f9263bSKirill A. Shutemov atomic_dec(compound_mapcount_ptr(page)); 1289be5d0a74SJohannes Weiner return; 129053f9263bSKirill A. Shutemov } 129153f9263bSKirill A. Shutemov 12928186eb6aSJohannes Weiner /* page still mapped by someone else? */ 1293dd78feddSKirill A. Shutemov if (compound && PageTransHuge(page)) { 1294a1528e21SMuchun Song int nr_pages = thp_nr_pages(page); 1295a1528e21SMuchun Song 1296a1528e21SMuchun Song for (i = 0, nr = 0; i < nr_pages; i++) { 1297dd78feddSKirill A. Shutemov if (atomic_add_negative(-1, &page[i]._mapcount)) 1298dd78feddSKirill A. Shutemov nr++; 1299dd78feddSKirill A. Shutemov } 1300dd78feddSKirill A. Shutemov if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) 1301be5d0a74SJohannes Weiner return; 130299cb0dbdSSong Liu if (PageSwapBacked(page)) 1303a1528e21SMuchun Song __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, 1304a1528e21SMuchun Song -nr_pages); 130599cb0dbdSSong Liu else 1306380780e7SMuchun Song __mod_lruvec_page_state(page, NR_FILE_PMDMAPPED, 1307380780e7SMuchun Song -nr_pages); 1308dd78feddSKirill A. Shutemov } else { 13098186eb6aSJohannes Weiner if (!atomic_add_negative(-1, &page->_mapcount)) 1310be5d0a74SJohannes Weiner return; 1311dd78feddSKirill A. Shutemov } 13128186eb6aSJohannes Weiner 13138186eb6aSJohannes Weiner /* 131400f3ca2cSJohannes Weiner * We use the irq-unsafe __{inc|mod}_lruvec_page_state because 13158186eb6aSJohannes Weiner * these counters are not modified in interrupt context, and 13168186eb6aSJohannes Weiner * pte lock(a spinlock) is held, which implies preemption disabled. 13178186eb6aSJohannes Weiner */ 131800f3ca2cSJohannes Weiner __mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr); 13198186eb6aSJohannes Weiner 13208186eb6aSJohannes Weiner if (unlikely(PageMlocked(page))) 13218186eb6aSJohannes Weiner clear_page_mlock(page); 13228186eb6aSJohannes Weiner } 13238186eb6aSJohannes Weiner 132453f9263bSKirill A. Shutemov static void page_remove_anon_compound_rmap(struct page *page) 132553f9263bSKirill A. Shutemov { 132653f9263bSKirill A. Shutemov int i, nr; 132753f9263bSKirill A. Shutemov 132853f9263bSKirill A. Shutemov if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) 132953f9263bSKirill A. Shutemov return; 133053f9263bSKirill A. Shutemov 133153f9263bSKirill A. Shutemov /* Hugepages are not counted in NR_ANON_PAGES for now. */ 133253f9263bSKirill A. Shutemov if (unlikely(PageHuge(page))) 133353f9263bSKirill A. Shutemov return; 133453f9263bSKirill A. Shutemov 133553f9263bSKirill A. Shutemov if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) 133653f9263bSKirill A. Shutemov return; 133753f9263bSKirill A. Shutemov 133869473e5dSMuchun Song __mod_lruvec_page_state(page, NR_ANON_THPS, -thp_nr_pages(page)); 133953f9263bSKirill A. Shutemov 134053f9263bSKirill A. Shutemov if (TestClearPageDoubleMap(page)) { 134153f9263bSKirill A. Shutemov /* 134253f9263bSKirill A. Shutemov * Subpages can be mapped with PTEs too. Check how many of 1343f1fe80d4SKirill A. Shutemov * them are still mapped. 134453f9263bSKirill A. Shutemov */ 13455eaf35abSMatthew Wilcox (Oracle) for (i = 0, nr = 0; i < thp_nr_pages(page); i++) { 134653f9263bSKirill A. Shutemov if (atomic_add_negative(-1, &page[i]._mapcount)) 134753f9263bSKirill A. Shutemov nr++; 134853f9263bSKirill A. Shutemov } 1349f1fe80d4SKirill A. Shutemov 1350f1fe80d4SKirill A. Shutemov /* 1351f1fe80d4SKirill A. Shutemov * Queue the page for deferred split if at least one small 1352f1fe80d4SKirill A. Shutemov * page of the compound page is unmapped, but at least one 1353f1fe80d4SKirill A. Shutemov * small page is still mapped. 1354f1fe80d4SKirill A. Shutemov */ 13555eaf35abSMatthew Wilcox (Oracle) if (nr && nr < thp_nr_pages(page)) 1356f1fe80d4SKirill A. Shutemov deferred_split_huge_page(page); 135753f9263bSKirill A. Shutemov } else { 13585eaf35abSMatthew Wilcox (Oracle) nr = thp_nr_pages(page); 135953f9263bSKirill A. Shutemov } 136053f9263bSKirill A. Shutemov 1361e90309c9SKirill A. Shutemov if (unlikely(PageMlocked(page))) 1362e90309c9SKirill A. Shutemov clear_page_mlock(page); 1363e90309c9SKirill A. Shutemov 1364f1fe80d4SKirill A. Shutemov if (nr) 1365be5d0a74SJohannes Weiner __mod_lruvec_page_state(page, NR_ANON_MAPPED, -nr); 136653f9263bSKirill A. Shutemov } 136753f9263bSKirill A. Shutemov 13681da177e4SLinus Torvalds /** 13691da177e4SLinus Torvalds * page_remove_rmap - take down pte mapping from a page 13701da177e4SLinus Torvalds * @page: page to remove mapping from 1371d281ee61SKirill A. Shutemov * @compound: uncharge the page as compound or small page 13721da177e4SLinus Torvalds * 1373b8072f09SHugh Dickins * The caller needs to hold the pte lock. 13741da177e4SLinus Torvalds */ 1375d281ee61SKirill A. Shutemov void page_remove_rmap(struct page *page, bool compound) 13761da177e4SLinus Torvalds { 1377be5d0a74SJohannes Weiner lock_page_memcg(page); 137889c06bd5SKAMEZAWA Hiroyuki 1379be5d0a74SJohannes Weiner if (!PageAnon(page)) { 1380be5d0a74SJohannes Weiner page_remove_file_rmap(page, compound); 1381be5d0a74SJohannes Weiner goto out; 1382be5d0a74SJohannes Weiner } 1383be5d0a74SJohannes Weiner 1384be5d0a74SJohannes Weiner if (compound) { 1385be5d0a74SJohannes Weiner page_remove_anon_compound_rmap(page); 1386be5d0a74SJohannes Weiner goto out; 1387be5d0a74SJohannes Weiner } 138853f9263bSKirill A. Shutemov 1389b904dcfeSKOSAKI Motohiro /* page still mapped by someone else? */ 1390b904dcfeSKOSAKI Motohiro if (!atomic_add_negative(-1, &page->_mapcount)) 1391be5d0a74SJohannes Weiner goto out; 13928186eb6aSJohannes Weiner 13931da177e4SLinus Torvalds /* 1394bea04b07SJianyu Zhan * We use the irq-unsafe __{inc|mod}_zone_page_stat because 1395bea04b07SJianyu Zhan * these counters are not modified in interrupt context, and 1396bea04b07SJianyu Zhan * pte lock(a spinlock) is held, which implies preemption disabled. 13970fe6e20bSNaoya Horiguchi */ 1398be5d0a74SJohannes Weiner __dec_lruvec_page_state(page, NR_ANON_MAPPED); 13998186eb6aSJohannes Weiner 1400e6c509f8SHugh Dickins if (unlikely(PageMlocked(page))) 1401e6c509f8SHugh Dickins clear_page_mlock(page); 14028186eb6aSJohannes Weiner 14039a982250SKirill A. Shutemov if (PageTransCompound(page)) 14049a982250SKirill A. Shutemov deferred_split_huge_page(compound_head(page)); 14059a982250SKirill A. Shutemov 140616f8c5b2SHugh Dickins /* 14071da177e4SLinus Torvalds * It would be tidy to reset the PageAnon mapping here, 14081da177e4SLinus Torvalds * but that might overwrite a racing page_add_anon_rmap 14091da177e4SLinus Torvalds * which increments mapcount after us but sets mapping 14102d4894b5SMel Gorman * before us: so leave the reset to free_unref_page, 14111da177e4SLinus Torvalds * and remember that it's only reliable while mapped. 14121da177e4SLinus Torvalds * Leaving it set also helps swapoff to reinstate ptes 14131da177e4SLinus Torvalds * faster for those pages still in swapcache. 14141da177e4SLinus Torvalds */ 1415be5d0a74SJohannes Weiner out: 1416be5d0a74SJohannes Weiner unlock_page_memcg(page); 14171da177e4SLinus Torvalds } 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds /* 142052629506SJoonsoo Kim * @arg: enum ttu_flags will be passed to this argument 14211da177e4SLinus Torvalds */ 1422e4b82222SMinchan Kim static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, 142352629506SJoonsoo Kim unsigned long address, void *arg) 14241da177e4SLinus Torvalds { 14251da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 1426c7ab0d2fSKirill A. Shutemov struct page_vma_mapped_walk pvmw = { 1427c7ab0d2fSKirill A. Shutemov .page = page, 1428c7ab0d2fSKirill A. Shutemov .vma = vma, 1429c7ab0d2fSKirill A. Shutemov .address = address, 1430c7ab0d2fSKirill A. Shutemov }; 14311da177e4SLinus Torvalds pte_t pteval; 1432c7ab0d2fSKirill A. Shutemov struct page *subpage; 1433785373b4SLinus Torvalds bool ret = true; 1434ac46d4f3SJérôme Glisse struct mmu_notifier_range range; 14354708f318SPalmer Dabbelt enum ttu_flags flags = (enum ttu_flags)(long)arg; 14361da177e4SLinus Torvalds 1437732ed558SHugh Dickins /* 1438732ed558SHugh Dickins * When racing against e.g. zap_pte_range() on another cpu, 1439732ed558SHugh Dickins * in between its ptep_get_and_clear_full() and page_remove_rmap(), 14401fb08ac6SYang Shi * try_to_unmap() may return before page_mapped() has become false, 1441732ed558SHugh Dickins * if page table locking is skipped: use TTU_SYNC to wait for that. 1442732ed558SHugh Dickins */ 1443732ed558SHugh Dickins if (flags & TTU_SYNC) 1444732ed558SHugh Dickins pvmw.flags = PVMW_SYNC; 1445732ed558SHugh Dickins 1446a98a2f0cSAlistair Popple if (flags & TTU_SPLIT_HUGE_PMD) 1447a98a2f0cSAlistair Popple split_huge_pmd_address(vma, address, false, page); 1448fec89c10SKirill A. Shutemov 1449369ea824SJérôme Glisse /* 1450017b1660SMike Kravetz * For THP, we have to assume the worse case ie pmd for invalidation. 1451017b1660SMike Kravetz * For hugetlb, it could be much worse if we need to do pud 1452017b1660SMike Kravetz * invalidation in the case of pmd sharing. 1453017b1660SMike Kravetz * 1454017b1660SMike Kravetz * Note that the page can not be free in this function as call of 1455017b1660SMike Kravetz * try_to_unmap() must hold a reference on the page. 1456369ea824SJérôme Glisse */ 1457494334e4SHugh Dickins range.end = PageKsm(page) ? 1458494334e4SHugh Dickins address + PAGE_SIZE : vma_address_end(page, vma); 14597269f999SJérôme Glisse mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1460494334e4SHugh Dickins address, range.end); 1461017b1660SMike Kravetz if (PageHuge(page)) { 1462017b1660SMike Kravetz /* 1463017b1660SMike Kravetz * If sharing is possible, start and end will be adjusted 1464017b1660SMike Kravetz * accordingly. 1465017b1660SMike Kravetz */ 1466ac46d4f3SJérôme Glisse adjust_range_if_pmd_sharing_possible(vma, &range.start, 1467ac46d4f3SJérôme Glisse &range.end); 1468017b1660SMike Kravetz } 1469ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_start(&range); 1470369ea824SJérôme Glisse 1471c7ab0d2fSKirill A. Shutemov while (page_vma_mapped_walk(&pvmw)) { 14721da177e4SLinus Torvalds /* 14731da177e4SLinus Torvalds * If the page is mlock()d, we cannot swap it out. 14741da177e4SLinus Torvalds */ 1475efdb6720SHugh Dickins if (!(flags & TTU_IGNORE_MLOCK) && 1476efdb6720SHugh Dickins (vma->vm_flags & VM_LOCKED)) { 14779a73f61bSKirill A. Shutemov /* 1478efdb6720SHugh Dickins * PTE-mapped THP are never marked as mlocked: so do 1479efdb6720SHugh Dickins * not set it on a DoubleMap THP, nor on an Anon THP 1480efdb6720SHugh Dickins * (which may still be PTE-mapped after DoubleMap was 1481efdb6720SHugh Dickins * cleared). But stop unmapping even in those cases. 14829a73f61bSKirill A. Shutemov */ 1483efdb6720SHugh Dickins if (!PageTransCompound(page) || (PageHead(page) && 1484efdb6720SHugh Dickins !PageDoubleMap(page) && !PageAnon(page))) 1485b87537d9SHugh Dickins mlock_vma_page(page); 1486c7ab0d2fSKirill A. Shutemov page_vma_mapped_walk_done(&pvmw); 1487efdb6720SHugh Dickins ret = false; 1488c7ab0d2fSKirill A. Shutemov break; 1489b87537d9SHugh Dickins } 1490c7ab0d2fSKirill A. Shutemov 14918346242aSKirill A. Shutemov /* Unexpected PMD-mapped THP? */ 14928346242aSKirill A. Shutemov VM_BUG_ON_PAGE(!pvmw.pte, page); 14938346242aSKirill A. Shutemov 14948346242aSKirill A. Shutemov subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); 1495785373b4SLinus Torvalds address = pvmw.address; 1496785373b4SLinus Torvalds 1497336bf30eSMike Kravetz if (PageHuge(page) && !PageAnon(page)) { 1498c0d0381aSMike Kravetz /* 1499c0d0381aSMike Kravetz * To call huge_pmd_unshare, i_mmap_rwsem must be 1500c0d0381aSMike Kravetz * held in write mode. Caller needs to explicitly 1501c0d0381aSMike Kravetz * do this outside rmap routines. 1502c0d0381aSMike Kravetz */ 1503c0d0381aSMike Kravetz VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); 150434ae204fSMike Kravetz if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) { 1505017b1660SMike Kravetz /* 1506017b1660SMike Kravetz * huge_pmd_unshare unmapped an entire PMD 1507017b1660SMike Kravetz * page. There is no way of knowing exactly 1508017b1660SMike Kravetz * which PMDs may be cached for this mm, so 1509017b1660SMike Kravetz * we must flush them all. start/end were 1510017b1660SMike Kravetz * already adjusted above to cover this range. 1511017b1660SMike Kravetz */ 1512ac46d4f3SJérôme Glisse flush_cache_range(vma, range.start, range.end); 1513ac46d4f3SJérôme Glisse flush_tlb_range(vma, range.start, range.end); 1514ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range(mm, range.start, 1515ac46d4f3SJérôme Glisse range.end); 1516017b1660SMike Kravetz 1517017b1660SMike Kravetz /* 1518017b1660SMike Kravetz * The ref count of the PMD page was dropped 1519017b1660SMike Kravetz * which is part of the way map counting 1520017b1660SMike Kravetz * is done for shared PMDs. Return 'true' 1521017b1660SMike Kravetz * here. When there is no other sharing, 1522017b1660SMike Kravetz * huge_pmd_unshare returns false and we will 1523017b1660SMike Kravetz * unmap the actual page and drop map count 1524017b1660SMike Kravetz * to zero. 1525017b1660SMike Kravetz */ 1526017b1660SMike Kravetz page_vma_mapped_walk_done(&pvmw); 1527017b1660SMike Kravetz break; 1528017b1660SMike Kravetz } 1529017b1660SMike Kravetz } 15308346242aSKirill A. Shutemov 15311da177e4SLinus Torvalds /* Nuke the page table entry. */ 1532785373b4SLinus Torvalds flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); 153372b252aeSMel Gorman if (should_defer_flush(mm, flags)) { 153472b252aeSMel Gorman /* 1535c7ab0d2fSKirill A. Shutemov * We clear the PTE but do not flush so potentially 1536c7ab0d2fSKirill A. Shutemov * a remote CPU could still be writing to the page. 1537c7ab0d2fSKirill A. Shutemov * If the entry was previously clean then the 1538c7ab0d2fSKirill A. Shutemov * architecture must guarantee that a clear->dirty 1539c7ab0d2fSKirill A. Shutemov * transition on a cached TLB entry is written through 1540c7ab0d2fSKirill A. Shutemov * and traps if the PTE is unmapped. 154172b252aeSMel Gorman */ 1542785373b4SLinus Torvalds pteval = ptep_get_and_clear(mm, address, pvmw.pte); 154372b252aeSMel Gorman 1544c7ab0d2fSKirill A. Shutemov set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); 154572b252aeSMel Gorman } else { 1546785373b4SLinus Torvalds pteval = ptep_clear_flush(vma, address, pvmw.pte); 154772b252aeSMel Gorman } 15481da177e4SLinus Torvalds 1549c7ab0d2fSKirill A. Shutemov /* Move the dirty bit to the page. Now the pte is gone. */ 15501da177e4SLinus Torvalds if (pte_dirty(pteval)) 15511da177e4SLinus Torvalds set_page_dirty(page); 15521da177e4SLinus Torvalds 1553365e9c87SHugh Dickins /* Update high watermark before we lower rss */ 1554365e9c87SHugh Dickins update_hiwater_rss(mm); 1555365e9c87SHugh Dickins 1556888b9f7cSAndi Kleen if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { 15575fd27b8eSPunit Agrawal pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); 15585d317b2bSNaoya Horiguchi if (PageHuge(page)) { 1559d8c6546bSMatthew Wilcox (Oracle) hugetlb_count_sub(compound_nr(page), mm); 1560785373b4SLinus Torvalds set_huge_swap_pte_at(mm, address, 15615fd27b8eSPunit Agrawal pvmw.pte, pteval, 15625fd27b8eSPunit Agrawal vma_mmu_pagesize(vma)); 15635d317b2bSNaoya Horiguchi } else { 1564eca56ff9SJerome Marchand dec_mm_counter(mm, mm_counter(page)); 1565785373b4SLinus Torvalds set_pte_at(mm, address, pvmw.pte, pteval); 15665f24ae58SNaoya Horiguchi } 1567c7ab0d2fSKirill A. Shutemov 1568bce73e48SChristian Borntraeger } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) { 156945961722SKonstantin Weitz /* 157045961722SKonstantin Weitz * The guest indicated that the page content is of no 157145961722SKonstantin Weitz * interest anymore. Simply discard the pte, vmscan 157245961722SKonstantin Weitz * will take care of the rest. 1573bce73e48SChristian Borntraeger * A future reference will then fault in a new zero 1574bce73e48SChristian Borntraeger * page. When userfaultfd is active, we must not drop 1575bce73e48SChristian Borntraeger * this page though, as its main user (postcopy 1576bce73e48SChristian Borntraeger * migration) will not expect userfaults on already 1577bce73e48SChristian Borntraeger * copied pages. 157845961722SKonstantin Weitz */ 1579eca56ff9SJerome Marchand dec_mm_counter(mm, mm_counter(page)); 15800f10851eSJérôme Glisse /* We have to invalidate as we cleared the pte */ 15810f10851eSJérôme Glisse mmu_notifier_invalidate_range(mm, address, 15820f10851eSJérôme Glisse address + PAGE_SIZE); 1583888b9f7cSAndi Kleen } else if (PageAnon(page)) { 1584c7ab0d2fSKirill A. Shutemov swp_entry_t entry = { .val = page_private(subpage) }; 1585179ef71cSCyrill Gorcunov pte_t swp_pte; 15861da177e4SLinus Torvalds /* 15871da177e4SLinus Torvalds * Store the swap location in the pte. 15881da177e4SLinus Torvalds * See handle_pte_fault() ... 15891da177e4SLinus Torvalds */ 1590eb94a878SMinchan Kim if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) { 1591eb94a878SMinchan Kim WARN_ON_ONCE(1); 159283612a94SMinchan Kim ret = false; 1593369ea824SJérôme Glisse /* We have to invalidate as we cleared the pte */ 15940f10851eSJérôme Glisse mmu_notifier_invalidate_range(mm, address, 15950f10851eSJérôme Glisse address + PAGE_SIZE); 1596eb94a878SMinchan Kim page_vma_mapped_walk_done(&pvmw); 1597eb94a878SMinchan Kim break; 1598eb94a878SMinchan Kim } 1599854e9ed0SMinchan Kim 1600802a3a92SShaohua Li /* MADV_FREE page check */ 1601802a3a92SShaohua Li if (!PageSwapBacked(page)) { 1602a128ca71SShaohua Li if (!PageDirty(page)) { 16030f10851eSJérôme Glisse /* Invalidate as we cleared the pte */ 16040f10851eSJérôme Glisse mmu_notifier_invalidate_range(mm, 16050f10851eSJérôme Glisse address, address + PAGE_SIZE); 1606854e9ed0SMinchan Kim dec_mm_counter(mm, MM_ANONPAGES); 1607854e9ed0SMinchan Kim goto discard; 1608854e9ed0SMinchan Kim } 1609854e9ed0SMinchan Kim 1610802a3a92SShaohua Li /* 1611802a3a92SShaohua Li * If the page was redirtied, it cannot be 1612802a3a92SShaohua Li * discarded. Remap the page to page table. 1613802a3a92SShaohua Li */ 1614785373b4SLinus Torvalds set_pte_at(mm, address, pvmw.pte, pteval); 161518863d3aSMinchan Kim SetPageSwapBacked(page); 1616e4b82222SMinchan Kim ret = false; 1617802a3a92SShaohua Li page_vma_mapped_walk_done(&pvmw); 1618802a3a92SShaohua Li break; 1619802a3a92SShaohua Li } 1620802a3a92SShaohua Li 1621570a335bSHugh Dickins if (swap_duplicate(entry) < 0) { 1622785373b4SLinus Torvalds set_pte_at(mm, address, pvmw.pte, pteval); 1623e4b82222SMinchan Kim ret = false; 1624c7ab0d2fSKirill A. Shutemov page_vma_mapped_walk_done(&pvmw); 1625c7ab0d2fSKirill A. Shutemov break; 1626570a335bSHugh Dickins } 1627ca827d55SKhalid Aziz if (arch_unmap_one(mm, vma, address, pteval) < 0) { 1628ca827d55SKhalid Aziz set_pte_at(mm, address, pvmw.pte, pteval); 1629ca827d55SKhalid Aziz ret = false; 1630ca827d55SKhalid Aziz page_vma_mapped_walk_done(&pvmw); 1631ca827d55SKhalid Aziz break; 1632ca827d55SKhalid Aziz } 16331da177e4SLinus Torvalds if (list_empty(&mm->mmlist)) { 16341da177e4SLinus Torvalds spin_lock(&mmlist_lock); 1635f412ac08SHugh Dickins if (list_empty(&mm->mmlist)) 16361da177e4SLinus Torvalds list_add(&mm->mmlist, &init_mm.mmlist); 16371da177e4SLinus Torvalds spin_unlock(&mmlist_lock); 16381da177e4SLinus Torvalds } 1639d559db08SKAMEZAWA Hiroyuki dec_mm_counter(mm, MM_ANONPAGES); 1640b084d435SKAMEZAWA Hiroyuki inc_mm_counter(mm, MM_SWAPENTS); 1641179ef71cSCyrill Gorcunov swp_pte = swp_entry_to_pte(entry); 1642179ef71cSCyrill Gorcunov if (pte_soft_dirty(pteval)) 1643179ef71cSCyrill Gorcunov swp_pte = pte_swp_mksoft_dirty(swp_pte); 1644f45ec5ffSPeter Xu if (pte_uffd_wp(pteval)) 1645f45ec5ffSPeter Xu swp_pte = pte_swp_mkuffd_wp(swp_pte); 1646785373b4SLinus Torvalds set_pte_at(mm, address, pvmw.pte, swp_pte); 16470f10851eSJérôme Glisse /* Invalidate as we cleared the pte */ 1648369ea824SJérôme Glisse mmu_notifier_invalidate_range(mm, address, 1649369ea824SJérôme Glisse address + PAGE_SIZE); 16500f10851eSJérôme Glisse } else { 16510f10851eSJérôme Glisse /* 1652906f9cdfSHugh Dickins * This is a locked file-backed page, thus it cannot 1653906f9cdfSHugh Dickins * be removed from the page cache and replaced by a new 1654906f9cdfSHugh Dickins * page before mmu_notifier_invalidate_range_end, so no 16550f10851eSJérôme Glisse * concurrent thread might update its page table to 16560f10851eSJérôme Glisse * point at new page while a device still is using this 16570f10851eSJérôme Glisse * page. 16580f10851eSJérôme Glisse * 1659ad56b738SMike Rapoport * See Documentation/vm/mmu_notifier.rst 16600f10851eSJérôme Glisse */ 16610f10851eSJérôme Glisse dec_mm_counter(mm, mm_counter_file(page)); 16620f10851eSJérôme Glisse } 16630f10851eSJérôme Glisse discard: 16640f10851eSJérôme Glisse /* 16650f10851eSJérôme Glisse * No need to call mmu_notifier_invalidate_range() it has be 16660f10851eSJérôme Glisse * done above for all cases requiring it to happen under page 16670f10851eSJérôme Glisse * table lock before mmu_notifier_invalidate_range_end() 16680f10851eSJérôme Glisse * 1669ad56b738SMike Rapoport * See Documentation/vm/mmu_notifier.rst 16700f10851eSJérôme Glisse */ 16710f10851eSJérôme Glisse page_remove_rmap(subpage, PageHuge(page)); 16720f10851eSJérôme Glisse put_page(page); 1673c7ab0d2fSKirill A. Shutemov } 1674369ea824SJérôme Glisse 1675ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_end(&range); 1676369ea824SJérôme Glisse 1677caed0f48SKOSAKI Motohiro return ret; 16781da177e4SLinus Torvalds } 16791da177e4SLinus Torvalds 168052629506SJoonsoo Kim static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) 168152629506SJoonsoo Kim { 1682222100eeSAnshuman Khandual return vma_is_temporary_stack(vma); 168352629506SJoonsoo Kim } 168452629506SJoonsoo Kim 1685b7e188ecSMiaohe Lin static int page_not_mapped(struct page *page) 168652629506SJoonsoo Kim { 1687b7e188ecSMiaohe Lin return !page_mapped(page); 16882a52bcbcSKirill A. Shutemov } 168952629506SJoonsoo Kim 16901da177e4SLinus Torvalds /** 16911da177e4SLinus Torvalds * try_to_unmap - try to remove all page table mappings to a page 16921da177e4SLinus Torvalds * @page: the page to get unmapped 169314fa31b8SAndi Kleen * @flags: action and flags 16941da177e4SLinus Torvalds * 16951da177e4SLinus Torvalds * Tries to remove all the page table entries which are mapping this 16961da177e4SLinus Torvalds * page, used in the pageout path. Caller must hold the page lock. 16971da177e4SLinus Torvalds * 16981fb08ac6SYang Shi * It is the caller's responsibility to check if the page is still 16991fb08ac6SYang Shi * mapped when needed (use TTU_SYNC to prevent accounting races). 17001da177e4SLinus Torvalds */ 17011fb08ac6SYang Shi void try_to_unmap(struct page *page, enum ttu_flags flags) 17021da177e4SLinus Torvalds { 170352629506SJoonsoo Kim struct rmap_walk_control rwc = { 170452629506SJoonsoo Kim .rmap_one = try_to_unmap_one, 1705802a3a92SShaohua Li .arg = (void *)flags, 1706b7e188ecSMiaohe Lin .done = page_not_mapped, 170752629506SJoonsoo Kim .anon_lock = page_lock_anon_vma_read, 170852629506SJoonsoo Kim }; 17091da177e4SLinus Torvalds 1710a98a2f0cSAlistair Popple if (flags & TTU_RMAP_LOCKED) 1711a98a2f0cSAlistair Popple rmap_walk_locked(page, &rwc); 1712a98a2f0cSAlistair Popple else 1713a98a2f0cSAlistair Popple rmap_walk(page, &rwc); 1714a98a2f0cSAlistair Popple } 1715a98a2f0cSAlistair Popple 1716a98a2f0cSAlistair Popple /* 1717a98a2f0cSAlistair Popple * @arg: enum ttu_flags will be passed to this argument. 1718a98a2f0cSAlistair Popple * 1719a98a2f0cSAlistair Popple * If TTU_SPLIT_HUGE_PMD is specified any PMD mappings will be split into PTEs 172064b586d1SHugh Dickins * containing migration entries. 1721a98a2f0cSAlistair Popple */ 1722a98a2f0cSAlistair Popple static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma, 1723a98a2f0cSAlistair Popple unsigned long address, void *arg) 1724a98a2f0cSAlistair Popple { 1725a98a2f0cSAlistair Popple struct mm_struct *mm = vma->vm_mm; 1726a98a2f0cSAlistair Popple struct page_vma_mapped_walk pvmw = { 1727a98a2f0cSAlistair Popple .page = page, 1728a98a2f0cSAlistair Popple .vma = vma, 1729a98a2f0cSAlistair Popple .address = address, 1730a98a2f0cSAlistair Popple }; 1731a98a2f0cSAlistair Popple pte_t pteval; 1732a98a2f0cSAlistair Popple struct page *subpage; 1733a98a2f0cSAlistair Popple bool ret = true; 1734a98a2f0cSAlistair Popple struct mmu_notifier_range range; 1735a98a2f0cSAlistair Popple enum ttu_flags flags = (enum ttu_flags)(long)arg; 1736a98a2f0cSAlistair Popple 1737a98a2f0cSAlistair Popple /* 1738a98a2f0cSAlistair Popple * When racing against e.g. zap_pte_range() on another cpu, 1739a98a2f0cSAlistair Popple * in between its ptep_get_and_clear_full() and page_remove_rmap(), 1740a98a2f0cSAlistair Popple * try_to_migrate() may return before page_mapped() has become false, 1741a98a2f0cSAlistair Popple * if page table locking is skipped: use TTU_SYNC to wait for that. 1742a98a2f0cSAlistair Popple */ 1743a98a2f0cSAlistair Popple if (flags & TTU_SYNC) 1744a98a2f0cSAlistair Popple pvmw.flags = PVMW_SYNC; 1745a98a2f0cSAlistair Popple 1746a98a2f0cSAlistair Popple /* 1747a98a2f0cSAlistair Popple * unmap_page() in mm/huge_memory.c is the only user of migration with 1748a98a2f0cSAlistair Popple * TTU_SPLIT_HUGE_PMD and it wants to freeze. 1749a98a2f0cSAlistair Popple */ 1750a98a2f0cSAlistair Popple if (flags & TTU_SPLIT_HUGE_PMD) 1751a98a2f0cSAlistair Popple split_huge_pmd_address(vma, address, true, page); 1752a98a2f0cSAlistair Popple 1753a98a2f0cSAlistair Popple /* 1754a98a2f0cSAlistair Popple * For THP, we have to assume the worse case ie pmd for invalidation. 1755a98a2f0cSAlistair Popple * For hugetlb, it could be much worse if we need to do pud 1756a98a2f0cSAlistair Popple * invalidation in the case of pmd sharing. 1757a98a2f0cSAlistair Popple * 1758a98a2f0cSAlistair Popple * Note that the page can not be free in this function as call of 1759a98a2f0cSAlistair Popple * try_to_unmap() must hold a reference on the page. 1760a98a2f0cSAlistair Popple */ 1761a98a2f0cSAlistair Popple range.end = PageKsm(page) ? 1762a98a2f0cSAlistair Popple address + PAGE_SIZE : vma_address_end(page, vma); 1763a98a2f0cSAlistair Popple mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1764a98a2f0cSAlistair Popple address, range.end); 1765a98a2f0cSAlistair Popple if (PageHuge(page)) { 1766a98a2f0cSAlistair Popple /* 1767a98a2f0cSAlistair Popple * If sharing is possible, start and end will be adjusted 1768a98a2f0cSAlistair Popple * accordingly. 1769a98a2f0cSAlistair Popple */ 1770a98a2f0cSAlistair Popple adjust_range_if_pmd_sharing_possible(vma, &range.start, 1771a98a2f0cSAlistair Popple &range.end); 1772a98a2f0cSAlistair Popple } 1773a98a2f0cSAlistair Popple mmu_notifier_invalidate_range_start(&range); 1774a98a2f0cSAlistair Popple 1775a98a2f0cSAlistair Popple while (page_vma_mapped_walk(&pvmw)) { 1776a98a2f0cSAlistair Popple #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1777a98a2f0cSAlistair Popple /* PMD-mapped THP migration entry */ 1778a98a2f0cSAlistair Popple if (!pvmw.pte) { 1779a98a2f0cSAlistair Popple VM_BUG_ON_PAGE(PageHuge(page) || 1780a98a2f0cSAlistair Popple !PageTransCompound(page), page); 1781a98a2f0cSAlistair Popple 1782a98a2f0cSAlistair Popple set_pmd_migration_entry(&pvmw, page); 1783a98a2f0cSAlistair Popple continue; 1784a98a2f0cSAlistair Popple } 1785a98a2f0cSAlistair Popple #endif 1786a98a2f0cSAlistair Popple 1787a98a2f0cSAlistair Popple /* Unexpected PMD-mapped THP? */ 1788a98a2f0cSAlistair Popple VM_BUG_ON_PAGE(!pvmw.pte, page); 1789a98a2f0cSAlistair Popple 1790a98a2f0cSAlistair Popple subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); 1791a98a2f0cSAlistair Popple address = pvmw.address; 1792a98a2f0cSAlistair Popple 1793a98a2f0cSAlistair Popple if (PageHuge(page) && !PageAnon(page)) { 1794a98a2f0cSAlistair Popple /* 1795a98a2f0cSAlistair Popple * To call huge_pmd_unshare, i_mmap_rwsem must be 1796a98a2f0cSAlistair Popple * held in write mode. Caller needs to explicitly 1797a98a2f0cSAlistair Popple * do this outside rmap routines. 1798a98a2f0cSAlistair Popple */ 1799a98a2f0cSAlistair Popple VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); 1800a98a2f0cSAlistair Popple if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) { 1801a98a2f0cSAlistair Popple /* 1802a98a2f0cSAlistair Popple * huge_pmd_unshare unmapped an entire PMD 1803a98a2f0cSAlistair Popple * page. There is no way of knowing exactly 1804a98a2f0cSAlistair Popple * which PMDs may be cached for this mm, so 1805a98a2f0cSAlistair Popple * we must flush them all. start/end were 1806a98a2f0cSAlistair Popple * already adjusted above to cover this range. 1807a98a2f0cSAlistair Popple */ 1808a98a2f0cSAlistair Popple flush_cache_range(vma, range.start, range.end); 1809a98a2f0cSAlistair Popple flush_tlb_range(vma, range.start, range.end); 1810a98a2f0cSAlistair Popple mmu_notifier_invalidate_range(mm, range.start, 1811a98a2f0cSAlistair Popple range.end); 1812a98a2f0cSAlistair Popple 1813a98a2f0cSAlistair Popple /* 1814a98a2f0cSAlistair Popple * The ref count of the PMD page was dropped 1815a98a2f0cSAlistair Popple * which is part of the way map counting 1816a98a2f0cSAlistair Popple * is done for shared PMDs. Return 'true' 1817a98a2f0cSAlistair Popple * here. When there is no other sharing, 1818a98a2f0cSAlistair Popple * huge_pmd_unshare returns false and we will 1819a98a2f0cSAlistair Popple * unmap the actual page and drop map count 1820a98a2f0cSAlistair Popple * to zero. 1821a98a2f0cSAlistair Popple */ 1822a98a2f0cSAlistair Popple page_vma_mapped_walk_done(&pvmw); 1823a98a2f0cSAlistair Popple break; 1824a98a2f0cSAlistair Popple } 1825a98a2f0cSAlistair Popple } 1826a98a2f0cSAlistair Popple 1827a98a2f0cSAlistair Popple /* Nuke the page table entry. */ 1828a98a2f0cSAlistair Popple flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); 1829a98a2f0cSAlistair Popple pteval = ptep_clear_flush(vma, address, pvmw.pte); 1830a98a2f0cSAlistair Popple 1831a98a2f0cSAlistair Popple /* Move the dirty bit to the page. Now the pte is gone. */ 1832a98a2f0cSAlistair Popple if (pte_dirty(pteval)) 1833a98a2f0cSAlistair Popple set_page_dirty(page); 1834a98a2f0cSAlistair Popple 1835a98a2f0cSAlistair Popple /* Update high watermark before we lower rss */ 1836a98a2f0cSAlistair Popple update_hiwater_rss(mm); 1837a98a2f0cSAlistair Popple 1838a98a2f0cSAlistair Popple if (is_zone_device_page(page)) { 18393d88705cSAlistair Popple unsigned long pfn = page_to_pfn(page); 1840a98a2f0cSAlistair Popple swp_entry_t entry; 1841a98a2f0cSAlistair Popple pte_t swp_pte; 1842a98a2f0cSAlistair Popple 1843a98a2f0cSAlistair Popple /* 1844a98a2f0cSAlistair Popple * Store the pfn of the page in a special migration 1845a98a2f0cSAlistair Popple * pte. do_swap_page() will wait until the migration 1846a98a2f0cSAlistair Popple * pte is removed and then restart fault handling. 1847a98a2f0cSAlistair Popple */ 18483d88705cSAlistair Popple entry = pte_to_swp_entry(pteval); 18493d88705cSAlistair Popple if (is_writable_device_private_entry(entry)) 18503d88705cSAlistair Popple entry = make_writable_migration_entry(pfn); 18513d88705cSAlistair Popple else 18523d88705cSAlistair Popple entry = make_readable_migration_entry(pfn); 1853a98a2f0cSAlistair Popple swp_pte = swp_entry_to_pte(entry); 1854a98a2f0cSAlistair Popple 1855a98a2f0cSAlistair Popple /* 1856a98a2f0cSAlistair Popple * pteval maps a zone device page and is therefore 1857a98a2f0cSAlistair Popple * a swap pte. 1858a98a2f0cSAlistair Popple */ 1859a98a2f0cSAlistair Popple if (pte_swp_soft_dirty(pteval)) 1860a98a2f0cSAlistair Popple swp_pte = pte_swp_mksoft_dirty(swp_pte); 1861a98a2f0cSAlistair Popple if (pte_swp_uffd_wp(pteval)) 1862a98a2f0cSAlistair Popple swp_pte = pte_swp_mkuffd_wp(swp_pte); 1863a98a2f0cSAlistair Popple set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte); 1864a98a2f0cSAlistair Popple /* 1865a98a2f0cSAlistair Popple * No need to invalidate here it will synchronize on 1866a98a2f0cSAlistair Popple * against the special swap migration pte. 1867a98a2f0cSAlistair Popple * 1868a98a2f0cSAlistair Popple * The assignment to subpage above was computed from a 1869a98a2f0cSAlistair Popple * swap PTE which results in an invalid pointer. 1870a98a2f0cSAlistair Popple * Since only PAGE_SIZE pages can currently be 1871a98a2f0cSAlistair Popple * migrated, just set it to page. This will need to be 1872a98a2f0cSAlistair Popple * changed when hugepage migrations to device private 1873a98a2f0cSAlistair Popple * memory are supported. 1874a98a2f0cSAlistair Popple */ 1875a98a2f0cSAlistair Popple subpage = page; 1876a98a2f0cSAlistair Popple } else if (PageHWPoison(page)) { 1877a98a2f0cSAlistair Popple pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); 1878a98a2f0cSAlistair Popple if (PageHuge(page)) { 1879a98a2f0cSAlistair Popple hugetlb_count_sub(compound_nr(page), mm); 1880a98a2f0cSAlistair Popple set_huge_swap_pte_at(mm, address, 1881a98a2f0cSAlistair Popple pvmw.pte, pteval, 1882a98a2f0cSAlistair Popple vma_mmu_pagesize(vma)); 1883a98a2f0cSAlistair Popple } else { 1884a98a2f0cSAlistair Popple dec_mm_counter(mm, mm_counter(page)); 1885a98a2f0cSAlistair Popple set_pte_at(mm, address, pvmw.pte, pteval); 1886a98a2f0cSAlistair Popple } 1887a98a2f0cSAlistair Popple 1888a98a2f0cSAlistair Popple } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) { 1889a98a2f0cSAlistair Popple /* 1890a98a2f0cSAlistair Popple * The guest indicated that the page content is of no 1891a98a2f0cSAlistair Popple * interest anymore. Simply discard the pte, vmscan 1892a98a2f0cSAlistair Popple * will take care of the rest. 1893a98a2f0cSAlistair Popple * A future reference will then fault in a new zero 1894a98a2f0cSAlistair Popple * page. When userfaultfd is active, we must not drop 1895a98a2f0cSAlistair Popple * this page though, as its main user (postcopy 1896a98a2f0cSAlistair Popple * migration) will not expect userfaults on already 1897a98a2f0cSAlistair Popple * copied pages. 1898a98a2f0cSAlistair Popple */ 1899a98a2f0cSAlistair Popple dec_mm_counter(mm, mm_counter(page)); 1900a98a2f0cSAlistair Popple /* We have to invalidate as we cleared the pte */ 1901a98a2f0cSAlistair Popple mmu_notifier_invalidate_range(mm, address, 1902a98a2f0cSAlistair Popple address + PAGE_SIZE); 1903a98a2f0cSAlistair Popple } else { 1904a98a2f0cSAlistair Popple swp_entry_t entry; 1905a98a2f0cSAlistair Popple pte_t swp_pte; 1906a98a2f0cSAlistair Popple 1907a98a2f0cSAlistair Popple if (arch_unmap_one(mm, vma, address, pteval) < 0) { 1908a98a2f0cSAlistair Popple set_pte_at(mm, address, pvmw.pte, pteval); 1909a98a2f0cSAlistair Popple ret = false; 1910a98a2f0cSAlistair Popple page_vma_mapped_walk_done(&pvmw); 1911a98a2f0cSAlistair Popple break; 1912a98a2f0cSAlistair Popple } 1913a98a2f0cSAlistair Popple 1914a98a2f0cSAlistair Popple /* 1915a98a2f0cSAlistair Popple * Store the pfn of the page in a special migration 1916a98a2f0cSAlistair Popple * pte. do_swap_page() will wait until the migration 1917a98a2f0cSAlistair Popple * pte is removed and then restart fault handling. 1918a98a2f0cSAlistair Popple */ 1919a98a2f0cSAlistair Popple if (pte_write(pteval)) 1920a98a2f0cSAlistair Popple entry = make_writable_migration_entry( 1921a98a2f0cSAlistair Popple page_to_pfn(subpage)); 1922a98a2f0cSAlistair Popple else 1923a98a2f0cSAlistair Popple entry = make_readable_migration_entry( 1924a98a2f0cSAlistair Popple page_to_pfn(subpage)); 1925a98a2f0cSAlistair Popple 1926a98a2f0cSAlistair Popple swp_pte = swp_entry_to_pte(entry); 1927a98a2f0cSAlistair Popple if (pte_soft_dirty(pteval)) 1928a98a2f0cSAlistair Popple swp_pte = pte_swp_mksoft_dirty(swp_pte); 1929a98a2f0cSAlistair Popple if (pte_uffd_wp(pteval)) 1930a98a2f0cSAlistair Popple swp_pte = pte_swp_mkuffd_wp(swp_pte); 1931a98a2f0cSAlistair Popple set_pte_at(mm, address, pvmw.pte, swp_pte); 1932a98a2f0cSAlistair Popple /* 1933a98a2f0cSAlistair Popple * No need to invalidate here it will synchronize on 1934a98a2f0cSAlistair Popple * against the special swap migration pte. 1935a98a2f0cSAlistair Popple */ 1936a98a2f0cSAlistair Popple } 1937a98a2f0cSAlistair Popple 1938a98a2f0cSAlistair Popple /* 1939a98a2f0cSAlistair Popple * No need to call mmu_notifier_invalidate_range() it has be 1940a98a2f0cSAlistair Popple * done above for all cases requiring it to happen under page 1941a98a2f0cSAlistair Popple * table lock before mmu_notifier_invalidate_range_end() 1942a98a2f0cSAlistair Popple * 1943a98a2f0cSAlistair Popple * See Documentation/vm/mmu_notifier.rst 1944a98a2f0cSAlistair Popple */ 1945a98a2f0cSAlistair Popple page_remove_rmap(subpage, PageHuge(page)); 1946a98a2f0cSAlistair Popple put_page(page); 1947a98a2f0cSAlistair Popple } 1948a98a2f0cSAlistair Popple 1949a98a2f0cSAlistair Popple mmu_notifier_invalidate_range_end(&range); 1950a98a2f0cSAlistair Popple 1951a98a2f0cSAlistair Popple return ret; 1952a98a2f0cSAlistair Popple } 1953a98a2f0cSAlistair Popple 1954a98a2f0cSAlistair Popple /** 1955a98a2f0cSAlistair Popple * try_to_migrate - try to replace all page table mappings with swap entries 1956a98a2f0cSAlistair Popple * @page: the page to replace page table entries for 1957a98a2f0cSAlistair Popple * @flags: action and flags 1958a98a2f0cSAlistair Popple * 1959a98a2f0cSAlistair Popple * Tries to remove all the page table entries which are mapping this page and 1960a98a2f0cSAlistair Popple * replace them with special swap entries. Caller must hold the page lock. 1961a98a2f0cSAlistair Popple */ 1962a98a2f0cSAlistair Popple void try_to_migrate(struct page *page, enum ttu_flags flags) 1963a98a2f0cSAlistair Popple { 1964a98a2f0cSAlistair Popple struct rmap_walk_control rwc = { 1965a98a2f0cSAlistair Popple .rmap_one = try_to_migrate_one, 1966a98a2f0cSAlistair Popple .arg = (void *)flags, 1967a98a2f0cSAlistair Popple .done = page_not_mapped, 1968a98a2f0cSAlistair Popple .anon_lock = page_lock_anon_vma_read, 1969a98a2f0cSAlistair Popple }; 1970a98a2f0cSAlistair Popple 1971a98a2f0cSAlistair Popple /* 1972a98a2f0cSAlistair Popple * Migration always ignores mlock and only supports TTU_RMAP_LOCKED and 1973a98a2f0cSAlistair Popple * TTU_SPLIT_HUGE_PMD and TTU_SYNC flags. 1974a98a2f0cSAlistair Popple */ 1975a98a2f0cSAlistair Popple if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 1976a98a2f0cSAlistair Popple TTU_SYNC))) 1977a98a2f0cSAlistair Popple return; 1978a98a2f0cSAlistair Popple 19796c855fceSHugh Dickins if (is_zone_device_page(page) && !is_device_private_page(page)) 19806c855fceSHugh Dickins return; 19816c855fceSHugh Dickins 198252629506SJoonsoo Kim /* 198352629506SJoonsoo Kim * During exec, a temporary VMA is setup and later moved. 198452629506SJoonsoo Kim * The VMA is moved under the anon_vma lock but not the 198552629506SJoonsoo Kim * page tables leading to a race where migration cannot 198652629506SJoonsoo Kim * find the migration ptes. Rather than increasing the 198752629506SJoonsoo Kim * locking requirements of exec(), migration skips 198852629506SJoonsoo Kim * temporary VMAs until after exec() completes. 198952629506SJoonsoo Kim */ 1990a98a2f0cSAlistair Popple if (!PageKsm(page) && PageAnon(page)) 199152629506SJoonsoo Kim rwc.invalid_vma = invalid_migration_vma; 199252629506SJoonsoo Kim 19932a52bcbcSKirill A. Shutemov if (flags & TTU_RMAP_LOCKED) 199433fc80e2SMinchan Kim rmap_walk_locked(page, &rwc); 19952a52bcbcSKirill A. Shutemov else 199633fc80e2SMinchan Kim rmap_walk(page, &rwc); 19971da177e4SLinus Torvalds } 199881b4082dSNikita Danilov 1999cd62734cSAlistair Popple /* 2000cd62734cSAlistair Popple * Walks the vma's mapping a page and mlocks the page if any locked vma's are 2001cd62734cSAlistair Popple * found. Once one is found the page is locked and the scan can be terminated. 2002b291f000SNick Piggin */ 2003cd62734cSAlistair Popple static bool page_mlock_one(struct page *page, struct vm_area_struct *vma, 2004cd62734cSAlistair Popple unsigned long address, void *unused) 2005cd62734cSAlistair Popple { 2006cd62734cSAlistair Popple struct page_vma_mapped_walk pvmw = { 2007cd62734cSAlistair Popple .page = page, 2008cd62734cSAlistair Popple .vma = vma, 2009cd62734cSAlistair Popple .address = address, 2010cd62734cSAlistair Popple }; 2011854e9ed0SMinchan Kim 2012cd62734cSAlistair Popple /* An un-locked vma doesn't have any pages to lock, continue the scan */ 2013cd62734cSAlistair Popple if (!(vma->vm_flags & VM_LOCKED)) 2014cd62734cSAlistair Popple return true; 2015cd62734cSAlistair Popple 2016cd62734cSAlistair Popple while (page_vma_mapped_walk(&pvmw)) { 2017cd62734cSAlistair Popple /* 2018cd62734cSAlistair Popple * Need to recheck under the ptl to serialise with 2019cd62734cSAlistair Popple * __munlock_pagevec_fill() after VM_LOCKED is cleared in 2020cd62734cSAlistair Popple * munlock_vma_pages_range(). 2021cd62734cSAlistair Popple */ 2022cd62734cSAlistair Popple if (vma->vm_flags & VM_LOCKED) { 2023d9770fccSHugh Dickins /* 2024efdb6720SHugh Dickins * PTE-mapped THP are never marked as mlocked; but 2025efdb6720SHugh Dickins * this function is never called on a DoubleMap THP, 2026efdb6720SHugh Dickins * nor on an Anon THP (which may still be PTE-mapped 2027efdb6720SHugh Dickins * after DoubleMap was cleared). 2028d9770fccSHugh Dickins */ 2029cd62734cSAlistair Popple mlock_vma_page(page); 2030cd62734cSAlistair Popple /* 2031023e1a8dSHugh Dickins * No need to scan further once the page is marked 2032023e1a8dSHugh Dickins * as mlocked. 2033cd62734cSAlistair Popple */ 2034023e1a8dSHugh Dickins page_vma_mapped_walk_done(&pvmw); 2035cd62734cSAlistair Popple return false; 2036cd62734cSAlistair Popple } 2037023e1a8dSHugh Dickins } 2038cd62734cSAlistair Popple 2039cd62734cSAlistair Popple return true; 2040cd62734cSAlistair Popple } 2041cd62734cSAlistair Popple 2042cd62734cSAlistair Popple /** 2043cd62734cSAlistair Popple * page_mlock - try to mlock a page 2044cd62734cSAlistair Popple * @page: the page to be mlocked 2045cd62734cSAlistair Popple * 2046cd62734cSAlistair Popple * Called from munlock code. Checks all of the VMAs mapping the page and mlocks 2047cd62734cSAlistair Popple * the page if any are found. The page will be returned with PG_mlocked cleared 2048cd62734cSAlistair Popple * if it is not mapped by any locked vmas. 2049cd62734cSAlistair Popple */ 2050cd62734cSAlistair Popple void page_mlock(struct page *page) 2051192d7232SMinchan Kim { 2052e8351ac9SJoonsoo Kim struct rmap_walk_control rwc = { 2053cd62734cSAlistair Popple .rmap_one = page_mlock_one, 2054e8351ac9SJoonsoo Kim .done = page_not_mapped, 2055e8351ac9SJoonsoo Kim .anon_lock = page_lock_anon_vma_read, 2056e8351ac9SJoonsoo Kim 2057e8351ac9SJoonsoo Kim }; 2058e8351ac9SJoonsoo Kim 2059309381feSSasha Levin VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page); 2060192d7232SMinchan Kim VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page); 2061b291f000SNick Piggin 2062efdb6720SHugh Dickins /* Anon THP are only marked as mlocked when singly mapped */ 2063efdb6720SHugh Dickins if (PageTransCompound(page) && PageAnon(page)) 2064efdb6720SHugh Dickins return; 2065efdb6720SHugh Dickins 2066192d7232SMinchan Kim rmap_walk(page, &rwc); 2067b291f000SNick Piggin } 2068e9995ef9SHugh Dickins 2069b756a3b5SAlistair Popple #ifdef CONFIG_DEVICE_PRIVATE 2070b756a3b5SAlistair Popple struct make_exclusive_args { 2071b756a3b5SAlistair Popple struct mm_struct *mm; 2072b756a3b5SAlistair Popple unsigned long address; 2073b756a3b5SAlistair Popple void *owner; 2074b756a3b5SAlistair Popple bool valid; 2075b756a3b5SAlistair Popple }; 2076b756a3b5SAlistair Popple 2077b756a3b5SAlistair Popple static bool page_make_device_exclusive_one(struct page *page, 2078b756a3b5SAlistair Popple struct vm_area_struct *vma, unsigned long address, void *priv) 2079b756a3b5SAlistair Popple { 2080b756a3b5SAlistair Popple struct mm_struct *mm = vma->vm_mm; 2081b756a3b5SAlistair Popple struct page_vma_mapped_walk pvmw = { 2082b756a3b5SAlistair Popple .page = page, 2083b756a3b5SAlistair Popple .vma = vma, 2084b756a3b5SAlistair Popple .address = address, 2085b756a3b5SAlistair Popple }; 2086b756a3b5SAlistair Popple struct make_exclusive_args *args = priv; 2087b756a3b5SAlistair Popple pte_t pteval; 2088b756a3b5SAlistair Popple struct page *subpage; 2089b756a3b5SAlistair Popple bool ret = true; 2090b756a3b5SAlistair Popple struct mmu_notifier_range range; 2091b756a3b5SAlistair Popple swp_entry_t entry; 2092b756a3b5SAlistair Popple pte_t swp_pte; 2093b756a3b5SAlistair Popple 2094b756a3b5SAlistair Popple mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma, 2095b756a3b5SAlistair Popple vma->vm_mm, address, min(vma->vm_end, 2096b756a3b5SAlistair Popple address + page_size(page)), args->owner); 2097b756a3b5SAlistair Popple mmu_notifier_invalidate_range_start(&range); 2098b756a3b5SAlistair Popple 2099b756a3b5SAlistair Popple while (page_vma_mapped_walk(&pvmw)) { 2100b756a3b5SAlistair Popple /* Unexpected PMD-mapped THP? */ 2101b756a3b5SAlistair Popple VM_BUG_ON_PAGE(!pvmw.pte, page); 2102b756a3b5SAlistair Popple 2103b756a3b5SAlistair Popple if (!pte_present(*pvmw.pte)) { 2104b756a3b5SAlistair Popple ret = false; 2105b756a3b5SAlistair Popple page_vma_mapped_walk_done(&pvmw); 2106b756a3b5SAlistair Popple break; 2107b756a3b5SAlistair Popple } 2108b756a3b5SAlistair Popple 2109b756a3b5SAlistair Popple subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); 2110b756a3b5SAlistair Popple address = pvmw.address; 2111b756a3b5SAlistair Popple 2112b756a3b5SAlistair Popple /* Nuke the page table entry. */ 2113b756a3b5SAlistair Popple flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); 2114b756a3b5SAlistair Popple pteval = ptep_clear_flush(vma, address, pvmw.pte); 2115b756a3b5SAlistair Popple 2116b756a3b5SAlistair Popple /* Move the dirty bit to the page. Now the pte is gone. */ 2117b756a3b5SAlistair Popple if (pte_dirty(pteval)) 2118b756a3b5SAlistair Popple set_page_dirty(page); 2119b756a3b5SAlistair Popple 2120b756a3b5SAlistair Popple /* 2121b756a3b5SAlistair Popple * Check that our target page is still mapped at the expected 2122b756a3b5SAlistair Popple * address. 2123b756a3b5SAlistair Popple */ 2124b756a3b5SAlistair Popple if (args->mm == mm && args->address == address && 2125b756a3b5SAlistair Popple pte_write(pteval)) 2126b756a3b5SAlistair Popple args->valid = true; 2127b756a3b5SAlistair Popple 2128b756a3b5SAlistair Popple /* 2129b756a3b5SAlistair Popple * Store the pfn of the page in a special migration 2130b756a3b5SAlistair Popple * pte. do_swap_page() will wait until the migration 2131b756a3b5SAlistair Popple * pte is removed and then restart fault handling. 2132b756a3b5SAlistair Popple */ 2133b756a3b5SAlistair Popple if (pte_write(pteval)) 2134b756a3b5SAlistair Popple entry = make_writable_device_exclusive_entry( 2135b756a3b5SAlistair Popple page_to_pfn(subpage)); 2136b756a3b5SAlistair Popple else 2137b756a3b5SAlistair Popple entry = make_readable_device_exclusive_entry( 2138b756a3b5SAlistair Popple page_to_pfn(subpage)); 2139b756a3b5SAlistair Popple swp_pte = swp_entry_to_pte(entry); 2140b756a3b5SAlistair Popple if (pte_soft_dirty(pteval)) 2141b756a3b5SAlistair Popple swp_pte = pte_swp_mksoft_dirty(swp_pte); 2142b756a3b5SAlistair Popple if (pte_uffd_wp(pteval)) 2143b756a3b5SAlistair Popple swp_pte = pte_swp_mkuffd_wp(swp_pte); 2144b756a3b5SAlistair Popple 2145b756a3b5SAlistair Popple set_pte_at(mm, address, pvmw.pte, swp_pte); 2146b756a3b5SAlistair Popple 2147b756a3b5SAlistair Popple /* 2148b756a3b5SAlistair Popple * There is a reference on the page for the swap entry which has 2149b756a3b5SAlistair Popple * been removed, so shouldn't take another. 2150b756a3b5SAlistair Popple */ 2151b756a3b5SAlistair Popple page_remove_rmap(subpage, false); 2152b756a3b5SAlistair Popple } 2153b756a3b5SAlistair Popple 2154b756a3b5SAlistair Popple mmu_notifier_invalidate_range_end(&range); 2155b756a3b5SAlistair Popple 2156b756a3b5SAlistair Popple return ret; 2157b756a3b5SAlistair Popple } 2158b756a3b5SAlistair Popple 2159b756a3b5SAlistair Popple /** 2160b756a3b5SAlistair Popple * page_make_device_exclusive - mark the page exclusively owned by a device 2161b756a3b5SAlistair Popple * @page: the page to replace page table entries for 2162b756a3b5SAlistair Popple * @mm: the mm_struct where the page is expected to be mapped 2163b756a3b5SAlistair Popple * @address: address where the page is expected to be mapped 2164b756a3b5SAlistair Popple * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier callbacks 2165b756a3b5SAlistair Popple * 2166b756a3b5SAlistair Popple * Tries to remove all the page table entries which are mapping this page and 2167b756a3b5SAlistair Popple * replace them with special device exclusive swap entries to grant a device 2168b756a3b5SAlistair Popple * exclusive access to the page. Caller must hold the page lock. 2169b756a3b5SAlistair Popple * 2170b756a3b5SAlistair Popple * Returns false if the page is still mapped, or if it could not be unmapped 2171b756a3b5SAlistair Popple * from the expected address. Otherwise returns true (success). 2172b756a3b5SAlistair Popple */ 2173b756a3b5SAlistair Popple static bool page_make_device_exclusive(struct page *page, struct mm_struct *mm, 2174b756a3b5SAlistair Popple unsigned long address, void *owner) 2175b756a3b5SAlistair Popple { 2176b756a3b5SAlistair Popple struct make_exclusive_args args = { 2177b756a3b5SAlistair Popple .mm = mm, 2178b756a3b5SAlistair Popple .address = address, 2179b756a3b5SAlistair Popple .owner = owner, 2180b756a3b5SAlistair Popple .valid = false, 2181b756a3b5SAlistair Popple }; 2182b756a3b5SAlistair Popple struct rmap_walk_control rwc = { 2183b756a3b5SAlistair Popple .rmap_one = page_make_device_exclusive_one, 2184b756a3b5SAlistair Popple .done = page_not_mapped, 2185b756a3b5SAlistair Popple .anon_lock = page_lock_anon_vma_read, 2186b756a3b5SAlistair Popple .arg = &args, 2187b756a3b5SAlistair Popple }; 2188b756a3b5SAlistair Popple 2189b756a3b5SAlistair Popple /* 2190b756a3b5SAlistair Popple * Restrict to anonymous pages for now to avoid potential writeback 2191b756a3b5SAlistair Popple * issues. Also tail pages shouldn't be passed to rmap_walk so skip 2192b756a3b5SAlistair Popple * those. 2193b756a3b5SAlistair Popple */ 2194b756a3b5SAlistair Popple if (!PageAnon(page) || PageTail(page)) 2195b756a3b5SAlistair Popple return false; 2196b756a3b5SAlistair Popple 2197b756a3b5SAlistair Popple rmap_walk(page, &rwc); 2198b756a3b5SAlistair Popple 2199b756a3b5SAlistair Popple return args.valid && !page_mapcount(page); 2200b756a3b5SAlistair Popple } 2201b756a3b5SAlistair Popple 2202b756a3b5SAlistair Popple /** 2203b756a3b5SAlistair Popple * make_device_exclusive_range() - Mark a range for exclusive use by a device 2204b756a3b5SAlistair Popple * @mm: mm_struct of assoicated target process 2205b756a3b5SAlistair Popple * @start: start of the region to mark for exclusive device access 2206b756a3b5SAlistair Popple * @end: end address of region 2207b756a3b5SAlistair Popple * @pages: returns the pages which were successfully marked for exclusive access 2208b756a3b5SAlistair Popple * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier to allow filtering 2209b756a3b5SAlistair Popple * 2210b756a3b5SAlistair Popple * Returns: number of pages found in the range by GUP. A page is marked for 2211b756a3b5SAlistair Popple * exclusive access only if the page pointer is non-NULL. 2212b756a3b5SAlistair Popple * 2213b756a3b5SAlistair Popple * This function finds ptes mapping page(s) to the given address range, locks 2214b756a3b5SAlistair Popple * them and replaces mappings with special swap entries preventing userspace CPU 2215b756a3b5SAlistair Popple * access. On fault these entries are replaced with the original mapping after 2216b756a3b5SAlistair Popple * calling MMU notifiers. 2217b756a3b5SAlistair Popple * 2218b756a3b5SAlistair Popple * A driver using this to program access from a device must use a mmu notifier 2219b756a3b5SAlistair Popple * critical section to hold a device specific lock during programming. Once 2220b756a3b5SAlistair Popple * programming is complete it should drop the page lock and reference after 2221b756a3b5SAlistair Popple * which point CPU access to the page will revoke the exclusive access. 2222b756a3b5SAlistair Popple */ 2223b756a3b5SAlistair Popple int make_device_exclusive_range(struct mm_struct *mm, unsigned long start, 2224b756a3b5SAlistair Popple unsigned long end, struct page **pages, 2225b756a3b5SAlistair Popple void *owner) 2226b756a3b5SAlistair Popple { 2227b756a3b5SAlistair Popple long npages = (end - start) >> PAGE_SHIFT; 2228b756a3b5SAlistair Popple long i; 2229b756a3b5SAlistair Popple 2230b756a3b5SAlistair Popple npages = get_user_pages_remote(mm, start, npages, 2231b756a3b5SAlistair Popple FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD, 2232b756a3b5SAlistair Popple pages, NULL, NULL); 2233b756a3b5SAlistair Popple if (npages < 0) 2234b756a3b5SAlistair Popple return npages; 2235b756a3b5SAlistair Popple 2236b756a3b5SAlistair Popple for (i = 0; i < npages; i++, start += PAGE_SIZE) { 2237b756a3b5SAlistair Popple if (!trylock_page(pages[i])) { 2238b756a3b5SAlistair Popple put_page(pages[i]); 2239b756a3b5SAlistair Popple pages[i] = NULL; 2240b756a3b5SAlistair Popple continue; 2241b756a3b5SAlistair Popple } 2242b756a3b5SAlistair Popple 2243b756a3b5SAlistair Popple if (!page_make_device_exclusive(pages[i], mm, start, owner)) { 2244b756a3b5SAlistair Popple unlock_page(pages[i]); 2245b756a3b5SAlistair Popple put_page(pages[i]); 2246b756a3b5SAlistair Popple pages[i] = NULL; 2247b756a3b5SAlistair Popple } 2248b756a3b5SAlistair Popple } 2249b756a3b5SAlistair Popple 2250b756a3b5SAlistair Popple return npages; 2251b756a3b5SAlistair Popple } 2252b756a3b5SAlistair Popple EXPORT_SYMBOL_GPL(make_device_exclusive_range); 2253b756a3b5SAlistair Popple #endif 2254b756a3b5SAlistair Popple 225501d8b20dSPeter Zijlstra void __put_anon_vma(struct anon_vma *anon_vma) 225676545066SRik van Riel { 225776545066SRik van Riel struct anon_vma *root = anon_vma->root; 225876545066SRik van Riel 2259624483f3SAndrey Ryabinin anon_vma_free(anon_vma); 226001d8b20dSPeter Zijlstra if (root != anon_vma && atomic_dec_and_test(&root->refcount)) 226176545066SRik van Riel anon_vma_free(root); 226276545066SRik van Riel } 226376545066SRik van Riel 22640dd1c7bbSJoonsoo Kim static struct anon_vma *rmap_walk_anon_lock(struct page *page, 22650dd1c7bbSJoonsoo Kim struct rmap_walk_control *rwc) 2266faecd8ddSJoonsoo Kim { 2267faecd8ddSJoonsoo Kim struct anon_vma *anon_vma; 2268faecd8ddSJoonsoo Kim 22690dd1c7bbSJoonsoo Kim if (rwc->anon_lock) 22700dd1c7bbSJoonsoo Kim return rwc->anon_lock(page); 22710dd1c7bbSJoonsoo Kim 2272faecd8ddSJoonsoo Kim /* 2273faecd8ddSJoonsoo Kim * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() 2274faecd8ddSJoonsoo Kim * because that depends on page_mapped(); but not all its usages 2275c1e8d7c6SMichel Lespinasse * are holding mmap_lock. Users without mmap_lock are required to 2276faecd8ddSJoonsoo Kim * take a reference count to prevent the anon_vma disappearing 2277faecd8ddSJoonsoo Kim */ 2278faecd8ddSJoonsoo Kim anon_vma = page_anon_vma(page); 2279faecd8ddSJoonsoo Kim if (!anon_vma) 2280faecd8ddSJoonsoo Kim return NULL; 2281faecd8ddSJoonsoo Kim 2282faecd8ddSJoonsoo Kim anon_vma_lock_read(anon_vma); 2283faecd8ddSJoonsoo Kim return anon_vma; 2284faecd8ddSJoonsoo Kim } 2285faecd8ddSJoonsoo Kim 2286e9995ef9SHugh Dickins /* 2287e8351ac9SJoonsoo Kim * rmap_walk_anon - do something to anonymous page using the object-based 2288e8351ac9SJoonsoo Kim * rmap method 2289e8351ac9SJoonsoo Kim * @page: the page to be handled 2290e8351ac9SJoonsoo Kim * @rwc: control variable according to each walk type 2291e8351ac9SJoonsoo Kim * 2292e8351ac9SJoonsoo Kim * Find all the mappings of a page using the mapping pointer and the vma chains 2293e8351ac9SJoonsoo Kim * contained in the anon_vma struct it points to. 2294e8351ac9SJoonsoo Kim * 2295cd62734cSAlistair Popple * When called from page_mlock(), the mmap_lock of the mm containing the vma 2296e8351ac9SJoonsoo Kim * where the page was found will be held for write. So, we won't recheck 2297e8351ac9SJoonsoo Kim * vm_flags for that VMA. That should be OK, because that vma shouldn't be 2298e8351ac9SJoonsoo Kim * LOCKED. 2299e9995ef9SHugh Dickins */ 23001df631aeSMinchan Kim static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc, 2301b9773199SKirill A. Shutemov bool locked) 2302e9995ef9SHugh Dickins { 2303e9995ef9SHugh Dickins struct anon_vma *anon_vma; 2304a8fa41adSKirill A. Shutemov pgoff_t pgoff_start, pgoff_end; 23055beb4930SRik van Riel struct anon_vma_chain *avc; 2306e9995ef9SHugh Dickins 2307b9773199SKirill A. Shutemov if (locked) { 2308b9773199SKirill A. Shutemov anon_vma = page_anon_vma(page); 2309b9773199SKirill A. Shutemov /* anon_vma disappear under us? */ 2310b9773199SKirill A. Shutemov VM_BUG_ON_PAGE(!anon_vma, page); 2311b9773199SKirill A. Shutemov } else { 23120dd1c7bbSJoonsoo Kim anon_vma = rmap_walk_anon_lock(page, rwc); 2313b9773199SKirill A. Shutemov } 2314e9995ef9SHugh Dickins if (!anon_vma) 23151df631aeSMinchan Kim return; 2316faecd8ddSJoonsoo Kim 2317a8fa41adSKirill A. Shutemov pgoff_start = page_to_pgoff(page); 23186c357848SMatthew Wilcox (Oracle) pgoff_end = pgoff_start + thp_nr_pages(page) - 1; 2319a8fa41adSKirill A. Shutemov anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, 2320a8fa41adSKirill A. Shutemov pgoff_start, pgoff_end) { 23215beb4930SRik van Riel struct vm_area_struct *vma = avc->vma; 2322e9995ef9SHugh Dickins unsigned long address = vma_address(page, vma); 23230dd1c7bbSJoonsoo Kim 2324494334e4SHugh Dickins VM_BUG_ON_VMA(address == -EFAULT, vma); 2325ad12695fSAndrea Arcangeli cond_resched(); 2326ad12695fSAndrea Arcangeli 23270dd1c7bbSJoonsoo Kim if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) 23280dd1c7bbSJoonsoo Kim continue; 23290dd1c7bbSJoonsoo Kim 2330e4b82222SMinchan Kim if (!rwc->rmap_one(page, vma, address, rwc->arg)) 2331e9995ef9SHugh Dickins break; 23320dd1c7bbSJoonsoo Kim if (rwc->done && rwc->done(page)) 23330dd1c7bbSJoonsoo Kim break; 2334e9995ef9SHugh Dickins } 2335b9773199SKirill A. Shutemov 2336b9773199SKirill A. Shutemov if (!locked) 23374fc3f1d6SIngo Molnar anon_vma_unlock_read(anon_vma); 2338e9995ef9SHugh Dickins } 2339e9995ef9SHugh Dickins 2340e8351ac9SJoonsoo Kim /* 2341e8351ac9SJoonsoo Kim * rmap_walk_file - do something to file page using the object-based rmap method 2342e8351ac9SJoonsoo Kim * @page: the page to be handled 2343e8351ac9SJoonsoo Kim * @rwc: control variable according to each walk type 2344e8351ac9SJoonsoo Kim * 2345e8351ac9SJoonsoo Kim * Find all the mappings of a page using the mapping pointer and the vma chains 2346e8351ac9SJoonsoo Kim * contained in the address_space struct it points to. 2347e8351ac9SJoonsoo Kim * 2348cd62734cSAlistair Popple * When called from page_mlock(), the mmap_lock of the mm containing the vma 2349e8351ac9SJoonsoo Kim * where the page was found will be held for write. So, we won't recheck 2350e8351ac9SJoonsoo Kim * vm_flags for that VMA. That should be OK, because that vma shouldn't be 2351e8351ac9SJoonsoo Kim * LOCKED. 2352e8351ac9SJoonsoo Kim */ 23531df631aeSMinchan Kim static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc, 2354b9773199SKirill A. Shutemov bool locked) 2355e9995ef9SHugh Dickins { 2356b9773199SKirill A. Shutemov struct address_space *mapping = page_mapping(page); 2357a8fa41adSKirill A. Shutemov pgoff_t pgoff_start, pgoff_end; 2358e9995ef9SHugh Dickins struct vm_area_struct *vma; 2359e9995ef9SHugh Dickins 23609f32624bSJoonsoo Kim /* 23619f32624bSJoonsoo Kim * The page lock not only makes sure that page->mapping cannot 23629f32624bSJoonsoo Kim * suddenly be NULLified by truncation, it makes sure that the 23639f32624bSJoonsoo Kim * structure at mapping cannot be freed and reused yet, 2364c8c06efaSDavidlohr Bueso * so we can safely take mapping->i_mmap_rwsem. 23659f32624bSJoonsoo Kim */ 236681d1b09cSSasha Levin VM_BUG_ON_PAGE(!PageLocked(page), page); 23679f32624bSJoonsoo Kim 2368e9995ef9SHugh Dickins if (!mapping) 23691df631aeSMinchan Kim return; 23703dec0ba0SDavidlohr Bueso 2371a8fa41adSKirill A. Shutemov pgoff_start = page_to_pgoff(page); 23726c357848SMatthew Wilcox (Oracle) pgoff_end = pgoff_start + thp_nr_pages(page) - 1; 2373b9773199SKirill A. Shutemov if (!locked) 23743dec0ba0SDavidlohr Bueso i_mmap_lock_read(mapping); 2375a8fa41adSKirill A. Shutemov vma_interval_tree_foreach(vma, &mapping->i_mmap, 2376a8fa41adSKirill A. Shutemov pgoff_start, pgoff_end) { 2377e9995ef9SHugh Dickins unsigned long address = vma_address(page, vma); 23780dd1c7bbSJoonsoo Kim 2379494334e4SHugh Dickins VM_BUG_ON_VMA(address == -EFAULT, vma); 2380ad12695fSAndrea Arcangeli cond_resched(); 2381ad12695fSAndrea Arcangeli 23820dd1c7bbSJoonsoo Kim if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) 23830dd1c7bbSJoonsoo Kim continue; 23840dd1c7bbSJoonsoo Kim 2385e4b82222SMinchan Kim if (!rwc->rmap_one(page, vma, address, rwc->arg)) 23860dd1c7bbSJoonsoo Kim goto done; 23870dd1c7bbSJoonsoo Kim if (rwc->done && rwc->done(page)) 23880dd1c7bbSJoonsoo Kim goto done; 2389e9995ef9SHugh Dickins } 23900dd1c7bbSJoonsoo Kim 23910dd1c7bbSJoonsoo Kim done: 2392b9773199SKirill A. Shutemov if (!locked) 23933dec0ba0SDavidlohr Bueso i_mmap_unlock_read(mapping); 2394e9995ef9SHugh Dickins } 2395e9995ef9SHugh Dickins 23961df631aeSMinchan Kim void rmap_walk(struct page *page, struct rmap_walk_control *rwc) 2397e9995ef9SHugh Dickins { 2398e9995ef9SHugh Dickins if (unlikely(PageKsm(page))) 23991df631aeSMinchan Kim rmap_walk_ksm(page, rwc); 2400e9995ef9SHugh Dickins else if (PageAnon(page)) 24011df631aeSMinchan Kim rmap_walk_anon(page, rwc, false); 2402e9995ef9SHugh Dickins else 24031df631aeSMinchan Kim rmap_walk_file(page, rwc, false); 2404b9773199SKirill A. Shutemov } 2405b9773199SKirill A. Shutemov 2406b9773199SKirill A. Shutemov /* Like rmap_walk, but caller holds relevant rmap lock */ 24071df631aeSMinchan Kim void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) 2408b9773199SKirill A. Shutemov { 2409b9773199SKirill A. Shutemov /* no ksm support for now */ 2410b9773199SKirill A. Shutemov VM_BUG_ON_PAGE(PageKsm(page), page); 2411b9773199SKirill A. Shutemov if (PageAnon(page)) 24121df631aeSMinchan Kim rmap_walk_anon(page, rwc, true); 2413b9773199SKirill A. Shutemov else 24141df631aeSMinchan Kim rmap_walk_file(page, rwc, true); 2415e9995ef9SHugh Dickins } 24160fe6e20bSNaoya Horiguchi 2417e3390f67SNaoya Horiguchi #ifdef CONFIG_HUGETLB_PAGE 24180fe6e20bSNaoya Horiguchi /* 2419451b9514SKirill Tkhai * The following two functions are for anonymous (private mapped) hugepages. 24200fe6e20bSNaoya Horiguchi * Unlike common anonymous pages, anonymous hugepages have no accounting code 24210fe6e20bSNaoya Horiguchi * and no lru code, because we handle hugepages differently from common pages. 24220fe6e20bSNaoya Horiguchi */ 24230fe6e20bSNaoya Horiguchi void hugepage_add_anon_rmap(struct page *page, 24240fe6e20bSNaoya Horiguchi struct vm_area_struct *vma, unsigned long address) 24250fe6e20bSNaoya Horiguchi { 24260fe6e20bSNaoya Horiguchi struct anon_vma *anon_vma = vma->anon_vma; 24270fe6e20bSNaoya Horiguchi int first; 2428a850ea30SNaoya Horiguchi 2429a850ea30SNaoya Horiguchi BUG_ON(!PageLocked(page)); 24300fe6e20bSNaoya Horiguchi BUG_ON(!anon_vma); 24315dbe0af4SHugh Dickins /* address might be in next vma when migration races vma_adjust */ 243253f9263bSKirill A. Shutemov first = atomic_inc_and_test(compound_mapcount_ptr(page)); 24330fe6e20bSNaoya Horiguchi if (first) 2434451b9514SKirill Tkhai __page_set_anon_rmap(page, vma, address, 0); 24350fe6e20bSNaoya Horiguchi } 24360fe6e20bSNaoya Horiguchi 24370fe6e20bSNaoya Horiguchi void hugepage_add_new_anon_rmap(struct page *page, 24380fe6e20bSNaoya Horiguchi struct vm_area_struct *vma, unsigned long address) 24390fe6e20bSNaoya Horiguchi { 24400fe6e20bSNaoya Horiguchi BUG_ON(address < vma->vm_start || address >= vma->vm_end); 244153f9263bSKirill A. Shutemov atomic_set(compound_mapcount_ptr(page), 0); 244247e29d32SJohn Hubbard if (hpage_pincount_available(page)) 244347e29d32SJohn Hubbard atomic_set(compound_pincount_ptr(page), 0); 244447e29d32SJohn Hubbard 2445451b9514SKirill Tkhai __page_set_anon_rmap(page, vma, address, 1); 24460fe6e20bSNaoya Horiguchi } 2447e3390f67SNaoya Horiguchi #endif /* CONFIG_HUGETLB_PAGE */ 2448