1 /* 2 * Copyright (C) 2008, 2009 Intel Corporation 3 * Authors: Andi Kleen, Fengguang Wu 4 * 5 * This software may be redistributed and/or modified under the terms of 6 * the GNU General Public License ("GPL") version 2 only as published by the 7 * Free Software Foundation. 8 * 9 * High level machine check handler. Handles pages reported by the 10 * hardware as being corrupted usually due to a multi-bit ECC memory or cache 11 * failure. 12 * 13 * In addition there is a "soft offline" entry point that allows stop using 14 * not-yet-corrupted-by-suspicious pages without killing anything. 15 * 16 * Handles page cache pages in various states. The tricky part 17 * here is that we can access any page asynchronously in respect to 18 * other VM users, because memory failures could happen anytime and 19 * anywhere. This could violate some of their assumptions. This is why 20 * this code has to be extremely careful. Generally it tries to use 21 * normal locking rules, as in get the standard locks, even if that means 22 * the error handling takes potentially a long time. 23 * 24 * There are several operations here with exponential complexity because 25 * of unsuitable VM data structures. For example the operation to map back 26 * from RMAP chains to processes has to walk the complete process list and 27 * has non linear complexity with the number. But since memory corruptions 28 * are rare we hope to get away with this. This avoids impacting the core 29 * VM. 30 */ 31 32 /* 33 * Notebook: 34 * - hugetlb needs more code 35 * - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages 36 * - pass bad pages to kdump next kernel 37 */ 38 #include <linux/kernel.h> 39 #include <linux/mm.h> 40 #include <linux/page-flags.h> 41 #include <linux/kernel-page-flags.h> 42 #include <linux/sched.h> 43 #include <linux/ksm.h> 44 #include <linux/rmap.h> 45 #include <linux/export.h> 46 #include <linux/pagemap.h> 47 #include <linux/swap.h> 48 #include <linux/backing-dev.h> 49 #include <linux/migrate.h> 50 #include <linux/page-isolation.h> 51 #include <linux/suspend.h> 52 #include <linux/slab.h> 53 #include <linux/swapops.h> 54 #include <linux/hugetlb.h> 55 #include <linux/memory_hotplug.h> 56 #include <linux/mm_inline.h> 57 #include <linux/kfifo.h> 58 #include "internal.h" 59 60 int sysctl_memory_failure_early_kill __read_mostly = 0; 61 62 int sysctl_memory_failure_recovery __read_mostly = 1; 63 64 atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0); 65 66 #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE) 67 68 u32 hwpoison_filter_enable = 0; 69 u32 hwpoison_filter_dev_major = ~0U; 70 u32 hwpoison_filter_dev_minor = ~0U; 71 u64 hwpoison_filter_flags_mask; 72 u64 hwpoison_filter_flags_value; 73 EXPORT_SYMBOL_GPL(hwpoison_filter_enable); 74 EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major); 75 EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor); 76 EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask); 77 EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value); 78 79 static int hwpoison_filter_dev(struct page *p) 80 { 81 struct address_space *mapping; 82 dev_t dev; 83 84 if (hwpoison_filter_dev_major == ~0U && 85 hwpoison_filter_dev_minor == ~0U) 86 return 0; 87 88 /* 89 * page_mapping() does not accept slab pages. 90 */ 91 if (PageSlab(p)) 92 return -EINVAL; 93 94 mapping = page_mapping(p); 95 if (mapping == NULL || mapping->host == NULL) 96 return -EINVAL; 97 98 dev = mapping->host->i_sb->s_dev; 99 if (hwpoison_filter_dev_major != ~0U && 100 hwpoison_filter_dev_major != MAJOR(dev)) 101 return -EINVAL; 102 if (hwpoison_filter_dev_minor != ~0U && 103 hwpoison_filter_dev_minor != MINOR(dev)) 104 return -EINVAL; 105 106 return 0; 107 } 108 109 static int hwpoison_filter_flags(struct page *p) 110 { 111 if (!hwpoison_filter_flags_mask) 112 return 0; 113 114 if ((stable_page_flags(p) & hwpoison_filter_flags_mask) == 115 hwpoison_filter_flags_value) 116 return 0; 117 else 118 return -EINVAL; 119 } 120 121 /* 122 * This allows stress tests to limit test scope to a collection of tasks 123 * by putting them under some memcg. This prevents killing unrelated/important 124 * processes such as /sbin/init. Note that the target task may share clean 125 * pages with init (eg. libc text), which is harmless. If the target task 126 * share _dirty_ pages with another task B, the test scheme must make sure B 127 * is also included in the memcg. At last, due to race conditions this filter 128 * can only guarantee that the page either belongs to the memcg tasks, or is 129 * a freed page. 130 */ 131 #ifdef CONFIG_MEMCG_SWAP 132 u64 hwpoison_filter_memcg; 133 EXPORT_SYMBOL_GPL(hwpoison_filter_memcg); 134 static int hwpoison_filter_task(struct page *p) 135 { 136 struct mem_cgroup *mem; 137 struct cgroup_subsys_state *css; 138 unsigned long ino; 139 140 if (!hwpoison_filter_memcg) 141 return 0; 142 143 mem = try_get_mem_cgroup_from_page(p); 144 if (!mem) 145 return -EINVAL; 146 147 css = mem_cgroup_css(mem); 148 /* root_mem_cgroup has NULL dentries */ 149 if (!css->cgroup->dentry) 150 return -EINVAL; 151 152 ino = css->cgroup->dentry->d_inode->i_ino; 153 css_put(css); 154 155 if (ino != hwpoison_filter_memcg) 156 return -EINVAL; 157 158 return 0; 159 } 160 #else 161 static int hwpoison_filter_task(struct page *p) { return 0; } 162 #endif 163 164 int hwpoison_filter(struct page *p) 165 { 166 if (!hwpoison_filter_enable) 167 return 0; 168 169 if (hwpoison_filter_dev(p)) 170 return -EINVAL; 171 172 if (hwpoison_filter_flags(p)) 173 return -EINVAL; 174 175 if (hwpoison_filter_task(p)) 176 return -EINVAL; 177 178 return 0; 179 } 180 #else 181 int hwpoison_filter(struct page *p) 182 { 183 return 0; 184 } 185 #endif 186 187 EXPORT_SYMBOL_GPL(hwpoison_filter); 188 189 /* 190 * Send all the processes who have the page mapped a signal. 191 * ``action optional'' if they are not immediately affected by the error 192 * ``action required'' if error happened in current execution context 193 */ 194 static int kill_proc(struct task_struct *t, unsigned long addr, int trapno, 195 unsigned long pfn, struct page *page, int flags) 196 { 197 struct siginfo si; 198 int ret; 199 200 printk(KERN_ERR 201 "MCE %#lx: Killing %s:%d due to hardware memory corruption\n", 202 pfn, t->comm, t->pid); 203 si.si_signo = SIGBUS; 204 si.si_errno = 0; 205 si.si_addr = (void *)addr; 206 #ifdef __ARCH_SI_TRAPNO 207 si.si_trapno = trapno; 208 #endif 209 si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT; 210 211 if ((flags & MF_ACTION_REQUIRED) && t == current) { 212 si.si_code = BUS_MCEERR_AR; 213 ret = force_sig_info(SIGBUS, &si, t); 214 } else { 215 /* 216 * Don't use force here, it's convenient if the signal 217 * can be temporarily blocked. 218 * This could cause a loop when the user sets SIGBUS 219 * to SIG_IGN, but hopefully no one will do that? 220 */ 221 si.si_code = BUS_MCEERR_AO; 222 ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */ 223 } 224 if (ret < 0) 225 printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n", 226 t->comm, t->pid, ret); 227 return ret; 228 } 229 230 /* 231 * When a unknown page type is encountered drain as many buffers as possible 232 * in the hope to turn the page into a LRU or free page, which we can handle. 233 */ 234 void shake_page(struct page *p, int access) 235 { 236 if (!PageSlab(p)) { 237 lru_add_drain_all(); 238 if (PageLRU(p)) 239 return; 240 drain_all_pages(); 241 if (PageLRU(p) || is_free_buddy_page(p)) 242 return; 243 } 244 245 /* 246 * Only call shrink_slab here (which would also shrink other caches) if 247 * access is not potentially fatal. 248 */ 249 if (access) { 250 int nr; 251 do { 252 struct shrink_control shrink = { 253 .gfp_mask = GFP_KERNEL, 254 }; 255 256 nr = shrink_slab(&shrink, 1000, 1000); 257 if (page_count(p) == 1) 258 break; 259 } while (nr > 10); 260 } 261 } 262 EXPORT_SYMBOL_GPL(shake_page); 263 264 /* 265 * Kill all processes that have a poisoned page mapped and then isolate 266 * the page. 267 * 268 * General strategy: 269 * Find all processes having the page mapped and kill them. 270 * But we keep a page reference around so that the page is not 271 * actually freed yet. 272 * Then stash the page away 273 * 274 * There's no convenient way to get back to mapped processes 275 * from the VMAs. So do a brute-force search over all 276 * running processes. 277 * 278 * Remember that machine checks are not common (or rather 279 * if they are common you have other problems), so this shouldn't 280 * be a performance issue. 281 * 282 * Also there are some races possible while we get from the 283 * error detection to actually handle it. 284 */ 285 286 struct to_kill { 287 struct list_head nd; 288 struct task_struct *tsk; 289 unsigned long addr; 290 char addr_valid; 291 }; 292 293 /* 294 * Failure handling: if we can't find or can't kill a process there's 295 * not much we can do. We just print a message and ignore otherwise. 296 */ 297 298 /* 299 * Schedule a process for later kill. 300 * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM. 301 * TBD would GFP_NOIO be enough? 302 */ 303 static void add_to_kill(struct task_struct *tsk, struct page *p, 304 struct vm_area_struct *vma, 305 struct list_head *to_kill, 306 struct to_kill **tkc) 307 { 308 struct to_kill *tk; 309 310 if (*tkc) { 311 tk = *tkc; 312 *tkc = NULL; 313 } else { 314 tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC); 315 if (!tk) { 316 printk(KERN_ERR 317 "MCE: Out of memory while machine check handling\n"); 318 return; 319 } 320 } 321 tk->addr = page_address_in_vma(p, vma); 322 tk->addr_valid = 1; 323 324 /* 325 * In theory we don't have to kill when the page was 326 * munmaped. But it could be also a mremap. Since that's 327 * likely very rare kill anyways just out of paranoia, but use 328 * a SIGKILL because the error is not contained anymore. 329 */ 330 if (tk->addr == -EFAULT) { 331 pr_info("MCE: Unable to find user space address %lx in %s\n", 332 page_to_pfn(p), tsk->comm); 333 tk->addr_valid = 0; 334 } 335 get_task_struct(tsk); 336 tk->tsk = tsk; 337 list_add_tail(&tk->nd, to_kill); 338 } 339 340 /* 341 * Kill the processes that have been collected earlier. 342 * 343 * Only do anything when DOIT is set, otherwise just free the list 344 * (this is used for clean pages which do not need killing) 345 * Also when FAIL is set do a force kill because something went 346 * wrong earlier. 347 */ 348 static void kill_procs(struct list_head *to_kill, int forcekill, int trapno, 349 int fail, struct page *page, unsigned long pfn, 350 int flags) 351 { 352 struct to_kill *tk, *next; 353 354 list_for_each_entry_safe (tk, next, to_kill, nd) { 355 if (forcekill) { 356 /* 357 * In case something went wrong with munmapping 358 * make sure the process doesn't catch the 359 * signal and then access the memory. Just kill it. 360 */ 361 if (fail || tk->addr_valid == 0) { 362 printk(KERN_ERR 363 "MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", 364 pfn, tk->tsk->comm, tk->tsk->pid); 365 force_sig(SIGKILL, tk->tsk); 366 } 367 368 /* 369 * In theory the process could have mapped 370 * something else on the address in-between. We could 371 * check for that, but we need to tell the 372 * process anyways. 373 */ 374 else if (kill_proc(tk->tsk, tk->addr, trapno, 375 pfn, page, flags) < 0) 376 printk(KERN_ERR 377 "MCE %#lx: Cannot send advisory machine check signal to %s:%d\n", 378 pfn, tk->tsk->comm, tk->tsk->pid); 379 } 380 put_task_struct(tk->tsk); 381 kfree(tk); 382 } 383 } 384 385 static int task_early_kill(struct task_struct *tsk) 386 { 387 if (!tsk->mm) 388 return 0; 389 if (tsk->flags & PF_MCE_PROCESS) 390 return !!(tsk->flags & PF_MCE_EARLY); 391 return sysctl_memory_failure_early_kill; 392 } 393 394 /* 395 * Collect processes when the error hit an anonymous page. 396 */ 397 static void collect_procs_anon(struct page *page, struct list_head *to_kill, 398 struct to_kill **tkc) 399 { 400 struct vm_area_struct *vma; 401 struct task_struct *tsk; 402 struct anon_vma *av; 403 404 av = page_lock_anon_vma(page); 405 if (av == NULL) /* Not actually mapped anymore */ 406 return; 407 408 read_lock(&tasklist_lock); 409 for_each_process (tsk) { 410 struct anon_vma_chain *vmac; 411 412 if (!task_early_kill(tsk)) 413 continue; 414 list_for_each_entry(vmac, &av->head, same_anon_vma) { 415 vma = vmac->vma; 416 if (!page_mapped_in_vma(page, vma)) 417 continue; 418 if (vma->vm_mm == tsk->mm) 419 add_to_kill(tsk, page, vma, to_kill, tkc); 420 } 421 } 422 read_unlock(&tasklist_lock); 423 page_unlock_anon_vma(av); 424 } 425 426 /* 427 * Collect processes when the error hit a file mapped page. 428 */ 429 static void collect_procs_file(struct page *page, struct list_head *to_kill, 430 struct to_kill **tkc) 431 { 432 struct vm_area_struct *vma; 433 struct task_struct *tsk; 434 struct prio_tree_iter iter; 435 struct address_space *mapping = page->mapping; 436 437 mutex_lock(&mapping->i_mmap_mutex); 438 read_lock(&tasklist_lock); 439 for_each_process(tsk) { 440 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); 441 442 if (!task_early_kill(tsk)) 443 continue; 444 445 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, 446 pgoff) { 447 /* 448 * Send early kill signal to tasks where a vma covers 449 * the page but the corrupted page is not necessarily 450 * mapped it in its pte. 451 * Assume applications who requested early kill want 452 * to be informed of all such data corruptions. 453 */ 454 if (vma->vm_mm == tsk->mm) 455 add_to_kill(tsk, page, vma, to_kill, tkc); 456 } 457 } 458 read_unlock(&tasklist_lock); 459 mutex_unlock(&mapping->i_mmap_mutex); 460 } 461 462 /* 463 * Collect the processes who have the corrupted page mapped to kill. 464 * This is done in two steps for locking reasons. 465 * First preallocate one tokill structure outside the spin locks, 466 * so that we can kill at least one process reasonably reliable. 467 */ 468 static void collect_procs(struct page *page, struct list_head *tokill) 469 { 470 struct to_kill *tk; 471 472 if (!page->mapping) 473 return; 474 475 tk = kmalloc(sizeof(struct to_kill), GFP_NOIO); 476 if (!tk) 477 return; 478 if (PageAnon(page)) 479 collect_procs_anon(page, tokill, &tk); 480 else 481 collect_procs_file(page, tokill, &tk); 482 kfree(tk); 483 } 484 485 /* 486 * Error handlers for various types of pages. 487 */ 488 489 enum outcome { 490 IGNORED, /* Error: cannot be handled */ 491 FAILED, /* Error: handling failed */ 492 DELAYED, /* Will be handled later */ 493 RECOVERED, /* Successfully recovered */ 494 }; 495 496 static const char *action_name[] = { 497 [IGNORED] = "Ignored", 498 [FAILED] = "Failed", 499 [DELAYED] = "Delayed", 500 [RECOVERED] = "Recovered", 501 }; 502 503 /* 504 * XXX: It is possible that a page is isolated from LRU cache, 505 * and then kept in swap cache or failed to remove from page cache. 506 * The page count will stop it from being freed by unpoison. 507 * Stress tests should be aware of this memory leak problem. 508 */ 509 static int delete_from_lru_cache(struct page *p) 510 { 511 if (!isolate_lru_page(p)) { 512 /* 513 * Clear sensible page flags, so that the buddy system won't 514 * complain when the page is unpoison-and-freed. 515 */ 516 ClearPageActive(p); 517 ClearPageUnevictable(p); 518 /* 519 * drop the page count elevated by isolate_lru_page() 520 */ 521 page_cache_release(p); 522 return 0; 523 } 524 return -EIO; 525 } 526 527 /* 528 * Error hit kernel page. 529 * Do nothing, try to be lucky and not touch this instead. For a few cases we 530 * could be more sophisticated. 531 */ 532 static int me_kernel(struct page *p, unsigned long pfn) 533 { 534 return IGNORED; 535 } 536 537 /* 538 * Page in unknown state. Do nothing. 539 */ 540 static int me_unknown(struct page *p, unsigned long pfn) 541 { 542 printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn); 543 return FAILED; 544 } 545 546 /* 547 * Clean (or cleaned) page cache page. 548 */ 549 static int me_pagecache_clean(struct page *p, unsigned long pfn) 550 { 551 int err; 552 int ret = FAILED; 553 struct address_space *mapping; 554 555 delete_from_lru_cache(p); 556 557 /* 558 * For anonymous pages we're done the only reference left 559 * should be the one m_f() holds. 560 */ 561 if (PageAnon(p)) 562 return RECOVERED; 563 564 /* 565 * Now truncate the page in the page cache. This is really 566 * more like a "temporary hole punch" 567 * Don't do this for block devices when someone else 568 * has a reference, because it could be file system metadata 569 * and that's not safe to truncate. 570 */ 571 mapping = page_mapping(p); 572 if (!mapping) { 573 /* 574 * Page has been teared down in the meanwhile 575 */ 576 return FAILED; 577 } 578 579 /* 580 * Truncation is a bit tricky. Enable it per file system for now. 581 * 582 * Open: to take i_mutex or not for this? Right now we don't. 583 */ 584 if (mapping->a_ops->error_remove_page) { 585 err = mapping->a_ops->error_remove_page(mapping, p); 586 if (err != 0) { 587 printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n", 588 pfn, err); 589 } else if (page_has_private(p) && 590 !try_to_release_page(p, GFP_NOIO)) { 591 pr_info("MCE %#lx: failed to release buffers\n", pfn); 592 } else { 593 ret = RECOVERED; 594 } 595 } else { 596 /* 597 * If the file system doesn't support it just invalidate 598 * This fails on dirty or anything with private pages 599 */ 600 if (invalidate_inode_page(p)) 601 ret = RECOVERED; 602 else 603 printk(KERN_INFO "MCE %#lx: Failed to invalidate\n", 604 pfn); 605 } 606 return ret; 607 } 608 609 /* 610 * Dirty cache page page 611 * Issues: when the error hit a hole page the error is not properly 612 * propagated. 613 */ 614 static int me_pagecache_dirty(struct page *p, unsigned long pfn) 615 { 616 struct address_space *mapping = page_mapping(p); 617 618 SetPageError(p); 619 /* TBD: print more information about the file. */ 620 if (mapping) { 621 /* 622 * IO error will be reported by write(), fsync(), etc. 623 * who check the mapping. 624 * This way the application knows that something went 625 * wrong with its dirty file data. 626 * 627 * There's one open issue: 628 * 629 * The EIO will be only reported on the next IO 630 * operation and then cleared through the IO map. 631 * Normally Linux has two mechanisms to pass IO error 632 * first through the AS_EIO flag in the address space 633 * and then through the PageError flag in the page. 634 * Since we drop pages on memory failure handling the 635 * only mechanism open to use is through AS_AIO. 636 * 637 * This has the disadvantage that it gets cleared on 638 * the first operation that returns an error, while 639 * the PageError bit is more sticky and only cleared 640 * when the page is reread or dropped. If an 641 * application assumes it will always get error on 642 * fsync, but does other operations on the fd before 643 * and the page is dropped between then the error 644 * will not be properly reported. 645 * 646 * This can already happen even without hwpoisoned 647 * pages: first on metadata IO errors (which only 648 * report through AS_EIO) or when the page is dropped 649 * at the wrong time. 650 * 651 * So right now we assume that the application DTRT on 652 * the first EIO, but we're not worse than other parts 653 * of the kernel. 654 */ 655 mapping_set_error(mapping, EIO); 656 } 657 658 return me_pagecache_clean(p, pfn); 659 } 660 661 /* 662 * Clean and dirty swap cache. 663 * 664 * Dirty swap cache page is tricky to handle. The page could live both in page 665 * cache and swap cache(ie. page is freshly swapped in). So it could be 666 * referenced concurrently by 2 types of PTEs: 667 * normal PTEs and swap PTEs. We try to handle them consistently by calling 668 * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs, 669 * and then 670 * - clear dirty bit to prevent IO 671 * - remove from LRU 672 * - but keep in the swap cache, so that when we return to it on 673 * a later page fault, we know the application is accessing 674 * corrupted data and shall be killed (we installed simple 675 * interception code in do_swap_page to catch it). 676 * 677 * Clean swap cache pages can be directly isolated. A later page fault will 678 * bring in the known good data from disk. 679 */ 680 static int me_swapcache_dirty(struct page *p, unsigned long pfn) 681 { 682 ClearPageDirty(p); 683 /* Trigger EIO in shmem: */ 684 ClearPageUptodate(p); 685 686 if (!delete_from_lru_cache(p)) 687 return DELAYED; 688 else 689 return FAILED; 690 } 691 692 static int me_swapcache_clean(struct page *p, unsigned long pfn) 693 { 694 delete_from_swap_cache(p); 695 696 if (!delete_from_lru_cache(p)) 697 return RECOVERED; 698 else 699 return FAILED; 700 } 701 702 /* 703 * Huge pages. Needs work. 704 * Issues: 705 * - Error on hugepage is contained in hugepage unit (not in raw page unit.) 706 * To narrow down kill region to one page, we need to break up pmd. 707 */ 708 static int me_huge_page(struct page *p, unsigned long pfn) 709 { 710 int res = 0; 711 struct page *hpage = compound_head(p); 712 /* 713 * We can safely recover from error on free or reserved (i.e. 714 * not in-use) hugepage by dequeuing it from freelist. 715 * To check whether a hugepage is in-use or not, we can't use 716 * page->lru because it can be used in other hugepage operations, 717 * such as __unmap_hugepage_range() and gather_surplus_pages(). 718 * So instead we use page_mapping() and PageAnon(). 719 * We assume that this function is called with page lock held, 720 * so there is no race between isolation and mapping/unmapping. 721 */ 722 if (!(page_mapping(hpage) || PageAnon(hpage))) { 723 res = dequeue_hwpoisoned_huge_page(hpage); 724 if (!res) 725 return RECOVERED; 726 } 727 return DELAYED; 728 } 729 730 /* 731 * Various page states we can handle. 732 * 733 * A page state is defined by its current page->flags bits. 734 * The table matches them in order and calls the right handler. 735 * 736 * This is quite tricky because we can access page at any time 737 * in its live cycle, so all accesses have to be extremely careful. 738 * 739 * This is not complete. More states could be added. 740 * For any missing state don't attempt recovery. 741 */ 742 743 #define dirty (1UL << PG_dirty) 744 #define sc (1UL << PG_swapcache) 745 #define unevict (1UL << PG_unevictable) 746 #define mlock (1UL << PG_mlocked) 747 #define writeback (1UL << PG_writeback) 748 #define lru (1UL << PG_lru) 749 #define swapbacked (1UL << PG_swapbacked) 750 #define head (1UL << PG_head) 751 #define tail (1UL << PG_tail) 752 #define compound (1UL << PG_compound) 753 #define slab (1UL << PG_slab) 754 #define reserved (1UL << PG_reserved) 755 756 static struct page_state { 757 unsigned long mask; 758 unsigned long res; 759 char *msg; 760 int (*action)(struct page *p, unsigned long pfn); 761 } error_states[] = { 762 { reserved, reserved, "reserved kernel", me_kernel }, 763 /* 764 * free pages are specially detected outside this table: 765 * PG_buddy pages only make a small fraction of all free pages. 766 */ 767 768 /* 769 * Could in theory check if slab page is free or if we can drop 770 * currently unused objects without touching them. But just 771 * treat it as standard kernel for now. 772 */ 773 { slab, slab, "kernel slab", me_kernel }, 774 775 #ifdef CONFIG_PAGEFLAGS_EXTENDED 776 { head, head, "huge", me_huge_page }, 777 { tail, tail, "huge", me_huge_page }, 778 #else 779 { compound, compound, "huge", me_huge_page }, 780 #endif 781 782 { sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty }, 783 { sc|dirty, sc, "swapcache", me_swapcache_clean }, 784 785 { unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty}, 786 { unevict, unevict, "unevictable LRU", me_pagecache_clean}, 787 788 { mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty }, 789 { mlock, mlock, "mlocked LRU", me_pagecache_clean }, 790 791 { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty }, 792 { lru|dirty, lru, "clean LRU", me_pagecache_clean }, 793 794 /* 795 * Catchall entry: must be at end. 796 */ 797 { 0, 0, "unknown page state", me_unknown }, 798 }; 799 800 #undef dirty 801 #undef sc 802 #undef unevict 803 #undef mlock 804 #undef writeback 805 #undef lru 806 #undef swapbacked 807 #undef head 808 #undef tail 809 #undef compound 810 #undef slab 811 #undef reserved 812 813 static void action_result(unsigned long pfn, char *msg, int result) 814 { 815 struct page *page = pfn_to_page(pfn); 816 817 printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n", 818 pfn, 819 PageDirty(page) ? "dirty " : "", 820 msg, action_name[result]); 821 } 822 823 static int page_action(struct page_state *ps, struct page *p, 824 unsigned long pfn) 825 { 826 int result; 827 int count; 828 829 result = ps->action(p, pfn); 830 action_result(pfn, ps->msg, result); 831 832 count = page_count(p) - 1; 833 if (ps->action == me_swapcache_dirty && result == DELAYED) 834 count--; 835 if (count != 0) { 836 printk(KERN_ERR 837 "MCE %#lx: %s page still referenced by %d users\n", 838 pfn, ps->msg, count); 839 result = FAILED; 840 } 841 842 /* Could do more checks here if page looks ok */ 843 /* 844 * Could adjust zone counters here to correct for the missing page. 845 */ 846 847 return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY; 848 } 849 850 /* 851 * Do all that is necessary to remove user space mappings. Unmap 852 * the pages and send SIGBUS to the processes if the data was dirty. 853 */ 854 static int hwpoison_user_mappings(struct page *p, unsigned long pfn, 855 int trapno, int flags) 856 { 857 enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; 858 struct address_space *mapping; 859 LIST_HEAD(tokill); 860 int ret; 861 int kill = 1, forcekill; 862 struct page *hpage = compound_head(p); 863 struct page *ppage; 864 865 if (PageReserved(p) || PageSlab(p)) 866 return SWAP_SUCCESS; 867 868 /* 869 * This check implies we don't kill processes if their pages 870 * are in the swap cache early. Those are always late kills. 871 */ 872 if (!page_mapped(hpage)) 873 return SWAP_SUCCESS; 874 875 if (PageKsm(p)) 876 return SWAP_FAIL; 877 878 if (PageSwapCache(p)) { 879 printk(KERN_ERR 880 "MCE %#lx: keeping poisoned page in swap cache\n", pfn); 881 ttu |= TTU_IGNORE_HWPOISON; 882 } 883 884 /* 885 * Propagate the dirty bit from PTEs to struct page first, because we 886 * need this to decide if we should kill or just drop the page. 887 * XXX: the dirty test could be racy: set_page_dirty() may not always 888 * be called inside page lock (it's recommended but not enforced). 889 */ 890 mapping = page_mapping(hpage); 891 if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping && 892 mapping_cap_writeback_dirty(mapping)) { 893 if (page_mkclean(hpage)) { 894 SetPageDirty(hpage); 895 } else { 896 kill = 0; 897 ttu |= TTU_IGNORE_HWPOISON; 898 printk(KERN_INFO 899 "MCE %#lx: corrupted page was clean: dropped without side effects\n", 900 pfn); 901 } 902 } 903 904 /* 905 * ppage: poisoned page 906 * if p is regular page(4k page) 907 * ppage == real poisoned page; 908 * else p is hugetlb or THP, ppage == head page. 909 */ 910 ppage = hpage; 911 912 if (PageTransHuge(hpage)) { 913 /* 914 * Verify that this isn't a hugetlbfs head page, the check for 915 * PageAnon is just for avoid tripping a split_huge_page 916 * internal debug check, as split_huge_page refuses to deal with 917 * anything that isn't an anon page. PageAnon can't go away fro 918 * under us because we hold a refcount on the hpage, without a 919 * refcount on the hpage. split_huge_page can't be safely called 920 * in the first place, having a refcount on the tail isn't 921 * enough * to be safe. 922 */ 923 if (!PageHuge(hpage) && PageAnon(hpage)) { 924 if (unlikely(split_huge_page(hpage))) { 925 /* 926 * FIXME: if splitting THP is failed, it is 927 * better to stop the following operation rather 928 * than causing panic by unmapping. System might 929 * survive if the page is freed later. 930 */ 931 printk(KERN_INFO 932 "MCE %#lx: failed to split THP\n", pfn); 933 934 BUG_ON(!PageHWPoison(p)); 935 return SWAP_FAIL; 936 } 937 /* THP is split, so ppage should be the real poisoned page. */ 938 ppage = p; 939 } 940 } 941 942 /* 943 * First collect all the processes that have the page 944 * mapped in dirty form. This has to be done before try_to_unmap, 945 * because ttu takes the rmap data structures down. 946 * 947 * Error handling: We ignore errors here because 948 * there's nothing that can be done. 949 */ 950 if (kill) 951 collect_procs(ppage, &tokill); 952 953 if (hpage != ppage) 954 lock_page(ppage); 955 956 ret = try_to_unmap(ppage, ttu); 957 if (ret != SWAP_SUCCESS) 958 printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n", 959 pfn, page_mapcount(ppage)); 960 961 if (hpage != ppage) 962 unlock_page(ppage); 963 964 /* 965 * Now that the dirty bit has been propagated to the 966 * struct page and all unmaps done we can decide if 967 * killing is needed or not. Only kill when the page 968 * was dirty or the process is not restartable, 969 * otherwise the tokill list is merely 970 * freed. When there was a problem unmapping earlier 971 * use a more force-full uncatchable kill to prevent 972 * any accesses to the poisoned memory. 973 */ 974 forcekill = PageDirty(ppage) || (flags & MF_MUST_KILL); 975 kill_procs(&tokill, forcekill, trapno, 976 ret != SWAP_SUCCESS, p, pfn, flags); 977 978 return ret; 979 } 980 981 static void set_page_hwpoison_huge_page(struct page *hpage) 982 { 983 int i; 984 int nr_pages = 1 << compound_trans_order(hpage); 985 for (i = 0; i < nr_pages; i++) 986 SetPageHWPoison(hpage + i); 987 } 988 989 static void clear_page_hwpoison_huge_page(struct page *hpage) 990 { 991 int i; 992 int nr_pages = 1 << compound_trans_order(hpage); 993 for (i = 0; i < nr_pages; i++) 994 ClearPageHWPoison(hpage + i); 995 } 996 997 /** 998 * memory_failure - Handle memory failure of a page. 999 * @pfn: Page Number of the corrupted page 1000 * @trapno: Trap number reported in the signal to user space. 1001 * @flags: fine tune action taken 1002 * 1003 * This function is called by the low level machine check code 1004 * of an architecture when it detects hardware memory corruption 1005 * of a page. It tries its best to recover, which includes 1006 * dropping pages, killing processes etc. 1007 * 1008 * The function is primarily of use for corruptions that 1009 * happen outside the current execution context (e.g. when 1010 * detected by a background scrubber) 1011 * 1012 * Must run in process context (e.g. a work queue) with interrupts 1013 * enabled and no spinlocks hold. 1014 */ 1015 int memory_failure(unsigned long pfn, int trapno, int flags) 1016 { 1017 struct page_state *ps; 1018 struct page *p; 1019 struct page *hpage; 1020 int res; 1021 unsigned int nr_pages; 1022 1023 if (!sysctl_memory_failure_recovery) 1024 panic("Memory failure from trap %d on page %lx", trapno, pfn); 1025 1026 if (!pfn_valid(pfn)) { 1027 printk(KERN_ERR 1028 "MCE %#lx: memory outside kernel control\n", 1029 pfn); 1030 return -ENXIO; 1031 } 1032 1033 p = pfn_to_page(pfn); 1034 hpage = compound_head(p); 1035 if (TestSetPageHWPoison(p)) { 1036 printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn); 1037 return 0; 1038 } 1039 1040 nr_pages = 1 << compound_trans_order(hpage); 1041 atomic_long_add(nr_pages, &mce_bad_pages); 1042 1043 /* 1044 * We need/can do nothing about count=0 pages. 1045 * 1) it's a free page, and therefore in safe hand: 1046 * prep_new_page() will be the gate keeper. 1047 * 2) it's a free hugepage, which is also safe: 1048 * an affected hugepage will be dequeued from hugepage freelist, 1049 * so there's no concern about reusing it ever after. 1050 * 3) it's part of a non-compound high order page. 1051 * Implies some kernel user: cannot stop them from 1052 * R/W the page; let's pray that the page has been 1053 * used and will be freed some time later. 1054 * In fact it's dangerous to directly bump up page count from 0, 1055 * that may make page_freeze_refs()/page_unfreeze_refs() mismatch. 1056 */ 1057 if (!(flags & MF_COUNT_INCREASED) && 1058 !get_page_unless_zero(hpage)) { 1059 if (is_free_buddy_page(p)) { 1060 action_result(pfn, "free buddy", DELAYED); 1061 return 0; 1062 } else if (PageHuge(hpage)) { 1063 /* 1064 * Check "just unpoisoned", "filter hit", and 1065 * "race with other subpage." 1066 */ 1067 lock_page(hpage); 1068 if (!PageHWPoison(hpage) 1069 || (hwpoison_filter(p) && TestClearPageHWPoison(p)) 1070 || (p != hpage && TestSetPageHWPoison(hpage))) { 1071 atomic_long_sub(nr_pages, &mce_bad_pages); 1072 return 0; 1073 } 1074 set_page_hwpoison_huge_page(hpage); 1075 res = dequeue_hwpoisoned_huge_page(hpage); 1076 action_result(pfn, "free huge", 1077 res ? IGNORED : DELAYED); 1078 unlock_page(hpage); 1079 return res; 1080 } else { 1081 action_result(pfn, "high order kernel", IGNORED); 1082 return -EBUSY; 1083 } 1084 } 1085 1086 /* 1087 * We ignore non-LRU pages for good reasons. 1088 * - PG_locked is only well defined for LRU pages and a few others 1089 * - to avoid races with __set_page_locked() 1090 * - to avoid races with __SetPageSlab*() (and more non-atomic ops) 1091 * The check (unnecessarily) ignores LRU pages being isolated and 1092 * walked by the page reclaim code, however that's not a big loss. 1093 */ 1094 if (!PageHuge(p) && !PageTransTail(p)) { 1095 if (!PageLRU(p)) 1096 shake_page(p, 0); 1097 if (!PageLRU(p)) { 1098 /* 1099 * shake_page could have turned it free. 1100 */ 1101 if (is_free_buddy_page(p)) { 1102 action_result(pfn, "free buddy, 2nd try", 1103 DELAYED); 1104 return 0; 1105 } 1106 action_result(pfn, "non LRU", IGNORED); 1107 put_page(p); 1108 return -EBUSY; 1109 } 1110 } 1111 1112 /* 1113 * Lock the page and wait for writeback to finish. 1114 * It's very difficult to mess with pages currently under IO 1115 * and in many cases impossible, so we just avoid it here. 1116 */ 1117 lock_page(hpage); 1118 1119 /* 1120 * unpoison always clear PG_hwpoison inside page lock 1121 */ 1122 if (!PageHWPoison(p)) { 1123 printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn); 1124 res = 0; 1125 goto out; 1126 } 1127 if (hwpoison_filter(p)) { 1128 if (TestClearPageHWPoison(p)) 1129 atomic_long_sub(nr_pages, &mce_bad_pages); 1130 unlock_page(hpage); 1131 put_page(hpage); 1132 return 0; 1133 } 1134 1135 /* 1136 * For error on the tail page, we should set PG_hwpoison 1137 * on the head page to show that the hugepage is hwpoisoned 1138 */ 1139 if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) { 1140 action_result(pfn, "hugepage already hardware poisoned", 1141 IGNORED); 1142 unlock_page(hpage); 1143 put_page(hpage); 1144 return 0; 1145 } 1146 /* 1147 * Set PG_hwpoison on all pages in an error hugepage, 1148 * because containment is done in hugepage unit for now. 1149 * Since we have done TestSetPageHWPoison() for the head page with 1150 * page lock held, we can safely set PG_hwpoison bits on tail pages. 1151 */ 1152 if (PageHuge(p)) 1153 set_page_hwpoison_huge_page(hpage); 1154 1155 wait_on_page_writeback(p); 1156 1157 /* 1158 * Now take care of user space mappings. 1159 * Abort on fail: __delete_from_page_cache() assumes unmapped page. 1160 */ 1161 if (hwpoison_user_mappings(p, pfn, trapno, flags) != SWAP_SUCCESS) { 1162 printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn); 1163 res = -EBUSY; 1164 goto out; 1165 } 1166 1167 /* 1168 * Torn down by someone else? 1169 */ 1170 if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) { 1171 action_result(pfn, "already truncated LRU", IGNORED); 1172 res = -EBUSY; 1173 goto out; 1174 } 1175 1176 res = -EBUSY; 1177 for (ps = error_states;; ps++) { 1178 if ((p->flags & ps->mask) == ps->res) { 1179 res = page_action(ps, p, pfn); 1180 break; 1181 } 1182 } 1183 out: 1184 unlock_page(hpage); 1185 return res; 1186 } 1187 EXPORT_SYMBOL_GPL(memory_failure); 1188 1189 #define MEMORY_FAILURE_FIFO_ORDER 4 1190 #define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER) 1191 1192 struct memory_failure_entry { 1193 unsigned long pfn; 1194 int trapno; 1195 int flags; 1196 }; 1197 1198 struct memory_failure_cpu { 1199 DECLARE_KFIFO(fifo, struct memory_failure_entry, 1200 MEMORY_FAILURE_FIFO_SIZE); 1201 spinlock_t lock; 1202 struct work_struct work; 1203 }; 1204 1205 static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu); 1206 1207 /** 1208 * memory_failure_queue - Schedule handling memory failure of a page. 1209 * @pfn: Page Number of the corrupted page 1210 * @trapno: Trap number reported in the signal to user space. 1211 * @flags: Flags for memory failure handling 1212 * 1213 * This function is called by the low level hardware error handler 1214 * when it detects hardware memory corruption of a page. It schedules 1215 * the recovering of error page, including dropping pages, killing 1216 * processes etc. 1217 * 1218 * The function is primarily of use for corruptions that 1219 * happen outside the current execution context (e.g. when 1220 * detected by a background scrubber) 1221 * 1222 * Can run in IRQ context. 1223 */ 1224 void memory_failure_queue(unsigned long pfn, int trapno, int flags) 1225 { 1226 struct memory_failure_cpu *mf_cpu; 1227 unsigned long proc_flags; 1228 struct memory_failure_entry entry = { 1229 .pfn = pfn, 1230 .trapno = trapno, 1231 .flags = flags, 1232 }; 1233 1234 mf_cpu = &get_cpu_var(memory_failure_cpu); 1235 spin_lock_irqsave(&mf_cpu->lock, proc_flags); 1236 if (kfifo_put(&mf_cpu->fifo, &entry)) 1237 schedule_work_on(smp_processor_id(), &mf_cpu->work); 1238 else 1239 pr_err("Memory failure: buffer overflow when queuing memory failure at 0x%#lx\n", 1240 pfn); 1241 spin_unlock_irqrestore(&mf_cpu->lock, proc_flags); 1242 put_cpu_var(memory_failure_cpu); 1243 } 1244 EXPORT_SYMBOL_GPL(memory_failure_queue); 1245 1246 static void memory_failure_work_func(struct work_struct *work) 1247 { 1248 struct memory_failure_cpu *mf_cpu; 1249 struct memory_failure_entry entry = { 0, }; 1250 unsigned long proc_flags; 1251 int gotten; 1252 1253 mf_cpu = &__get_cpu_var(memory_failure_cpu); 1254 for (;;) { 1255 spin_lock_irqsave(&mf_cpu->lock, proc_flags); 1256 gotten = kfifo_get(&mf_cpu->fifo, &entry); 1257 spin_unlock_irqrestore(&mf_cpu->lock, proc_flags); 1258 if (!gotten) 1259 break; 1260 memory_failure(entry.pfn, entry.trapno, entry.flags); 1261 } 1262 } 1263 1264 static int __init memory_failure_init(void) 1265 { 1266 struct memory_failure_cpu *mf_cpu; 1267 int cpu; 1268 1269 for_each_possible_cpu(cpu) { 1270 mf_cpu = &per_cpu(memory_failure_cpu, cpu); 1271 spin_lock_init(&mf_cpu->lock); 1272 INIT_KFIFO(mf_cpu->fifo); 1273 INIT_WORK(&mf_cpu->work, memory_failure_work_func); 1274 } 1275 1276 return 0; 1277 } 1278 core_initcall(memory_failure_init); 1279 1280 /** 1281 * unpoison_memory - Unpoison a previously poisoned page 1282 * @pfn: Page number of the to be unpoisoned page 1283 * 1284 * Software-unpoison a page that has been poisoned by 1285 * memory_failure() earlier. 1286 * 1287 * This is only done on the software-level, so it only works 1288 * for linux injected failures, not real hardware failures 1289 * 1290 * Returns 0 for success, otherwise -errno. 1291 */ 1292 int unpoison_memory(unsigned long pfn) 1293 { 1294 struct page *page; 1295 struct page *p; 1296 int freeit = 0; 1297 unsigned int nr_pages; 1298 1299 if (!pfn_valid(pfn)) 1300 return -ENXIO; 1301 1302 p = pfn_to_page(pfn); 1303 page = compound_head(p); 1304 1305 if (!PageHWPoison(p)) { 1306 pr_info("MCE: Page was already unpoisoned %#lx\n", pfn); 1307 return 0; 1308 } 1309 1310 nr_pages = 1 << compound_trans_order(page); 1311 1312 if (!get_page_unless_zero(page)) { 1313 /* 1314 * Since HWPoisoned hugepage should have non-zero refcount, 1315 * race between memory failure and unpoison seems to happen. 1316 * In such case unpoison fails and memory failure runs 1317 * to the end. 1318 */ 1319 if (PageHuge(page)) { 1320 pr_info("MCE: Memory failure is now running on free hugepage %#lx\n", pfn); 1321 return 0; 1322 } 1323 if (TestClearPageHWPoison(p)) 1324 atomic_long_sub(nr_pages, &mce_bad_pages); 1325 pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn); 1326 return 0; 1327 } 1328 1329 lock_page(page); 1330 /* 1331 * This test is racy because PG_hwpoison is set outside of page lock. 1332 * That's acceptable because that won't trigger kernel panic. Instead, 1333 * the PG_hwpoison page will be caught and isolated on the entrance to 1334 * the free buddy page pool. 1335 */ 1336 if (TestClearPageHWPoison(page)) { 1337 pr_info("MCE: Software-unpoisoned page %#lx\n", pfn); 1338 atomic_long_sub(nr_pages, &mce_bad_pages); 1339 freeit = 1; 1340 if (PageHuge(page)) 1341 clear_page_hwpoison_huge_page(page); 1342 } 1343 unlock_page(page); 1344 1345 put_page(page); 1346 if (freeit) 1347 put_page(page); 1348 1349 return 0; 1350 } 1351 EXPORT_SYMBOL(unpoison_memory); 1352 1353 static struct page *new_page(struct page *p, unsigned long private, int **x) 1354 { 1355 int nid = page_to_nid(p); 1356 if (PageHuge(p)) 1357 return alloc_huge_page_node(page_hstate(compound_head(p)), 1358 nid); 1359 else 1360 return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0); 1361 } 1362 1363 /* 1364 * Safely get reference count of an arbitrary page. 1365 * Returns 0 for a free page, -EIO for a zero refcount page 1366 * that is not free, and 1 for any other page type. 1367 * For 1 the page is returned with increased page count, otherwise not. 1368 */ 1369 static int get_any_page(struct page *p, unsigned long pfn, int flags) 1370 { 1371 int ret; 1372 1373 if (flags & MF_COUNT_INCREASED) 1374 return 1; 1375 1376 /* 1377 * The lock_memory_hotplug prevents a race with memory hotplug. 1378 * This is a big hammer, a better would be nicer. 1379 */ 1380 lock_memory_hotplug(); 1381 1382 /* 1383 * Isolate the page, so that it doesn't get reallocated if it 1384 * was free. 1385 */ 1386 set_migratetype_isolate(p); 1387 /* 1388 * When the target page is a free hugepage, just remove it 1389 * from free hugepage list. 1390 */ 1391 if (!get_page_unless_zero(compound_head(p))) { 1392 if (PageHuge(p)) { 1393 pr_info("%s: %#lx free huge page\n", __func__, pfn); 1394 ret = dequeue_hwpoisoned_huge_page(compound_head(p)); 1395 } else if (is_free_buddy_page(p)) { 1396 pr_info("%s: %#lx free buddy page\n", __func__, pfn); 1397 /* Set hwpoison bit while page is still isolated */ 1398 SetPageHWPoison(p); 1399 ret = 0; 1400 } else { 1401 pr_info("%s: %#lx: unknown zero refcount page type %lx\n", 1402 __func__, pfn, p->flags); 1403 ret = -EIO; 1404 } 1405 } else { 1406 /* Not a free page */ 1407 ret = 1; 1408 } 1409 unset_migratetype_isolate(p, MIGRATE_MOVABLE); 1410 unlock_memory_hotplug(); 1411 return ret; 1412 } 1413 1414 static int soft_offline_huge_page(struct page *page, int flags) 1415 { 1416 int ret; 1417 unsigned long pfn = page_to_pfn(page); 1418 struct page *hpage = compound_head(page); 1419 1420 ret = get_any_page(page, pfn, flags); 1421 if (ret < 0) 1422 return ret; 1423 if (ret == 0) 1424 goto done; 1425 1426 if (PageHWPoison(hpage)) { 1427 put_page(hpage); 1428 pr_info("soft offline: %#lx hugepage already poisoned\n", pfn); 1429 return -EBUSY; 1430 } 1431 1432 /* Keep page count to indicate a given hugepage is isolated. */ 1433 ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, false, 1434 MIGRATE_SYNC); 1435 put_page(hpage); 1436 if (ret) { 1437 pr_info("soft offline: %#lx: migration failed %d, type %lx\n", 1438 pfn, ret, page->flags); 1439 return ret; 1440 } 1441 done: 1442 if (!PageHWPoison(hpage)) 1443 atomic_long_add(1 << compound_trans_order(hpage), 1444 &mce_bad_pages); 1445 set_page_hwpoison_huge_page(hpage); 1446 dequeue_hwpoisoned_huge_page(hpage); 1447 /* keep elevated page count for bad page */ 1448 return ret; 1449 } 1450 1451 /** 1452 * soft_offline_page - Soft offline a page. 1453 * @page: page to offline 1454 * @flags: flags. Same as memory_failure(). 1455 * 1456 * Returns 0 on success, otherwise negated errno. 1457 * 1458 * Soft offline a page, by migration or invalidation, 1459 * without killing anything. This is for the case when 1460 * a page is not corrupted yet (so it's still valid to access), 1461 * but has had a number of corrected errors and is better taken 1462 * out. 1463 * 1464 * The actual policy on when to do that is maintained by 1465 * user space. 1466 * 1467 * This should never impact any application or cause data loss, 1468 * however it might take some time. 1469 * 1470 * This is not a 100% solution for all memory, but tries to be 1471 * ``good enough'' for the majority of memory. 1472 */ 1473 int soft_offline_page(struct page *page, int flags) 1474 { 1475 int ret; 1476 unsigned long pfn = page_to_pfn(page); 1477 1478 if (PageHuge(page)) 1479 return soft_offline_huge_page(page, flags); 1480 1481 ret = get_any_page(page, pfn, flags); 1482 if (ret < 0) 1483 return ret; 1484 if (ret == 0) 1485 goto done; 1486 1487 /* 1488 * Page cache page we can handle? 1489 */ 1490 if (!PageLRU(page)) { 1491 /* 1492 * Try to free it. 1493 */ 1494 put_page(page); 1495 shake_page(page, 1); 1496 1497 /* 1498 * Did it turn free? 1499 */ 1500 ret = get_any_page(page, pfn, 0); 1501 if (ret < 0) 1502 return ret; 1503 if (ret == 0) 1504 goto done; 1505 } 1506 if (!PageLRU(page)) { 1507 pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", 1508 pfn, page->flags); 1509 return -EIO; 1510 } 1511 1512 lock_page(page); 1513 wait_on_page_writeback(page); 1514 1515 /* 1516 * Synchronized using the page lock with memory_failure() 1517 */ 1518 if (PageHWPoison(page)) { 1519 unlock_page(page); 1520 put_page(page); 1521 pr_info("soft offline: %#lx page already poisoned\n", pfn); 1522 return -EBUSY; 1523 } 1524 1525 /* 1526 * Try to invalidate first. This should work for 1527 * non dirty unmapped page cache pages. 1528 */ 1529 ret = invalidate_inode_page(page); 1530 unlock_page(page); 1531 /* 1532 * RED-PEN would be better to keep it isolated here, but we 1533 * would need to fix isolation locking first. 1534 */ 1535 if (ret == 1) { 1536 put_page(page); 1537 ret = 0; 1538 pr_info("soft_offline: %#lx: invalidated\n", pfn); 1539 goto done; 1540 } 1541 1542 /* 1543 * Simple invalidation didn't work. 1544 * Try to migrate to a new page instead. migrate.c 1545 * handles a large number of cases for us. 1546 */ 1547 ret = isolate_lru_page(page); 1548 /* 1549 * Drop page reference which is came from get_any_page() 1550 * successful isolate_lru_page() already took another one. 1551 */ 1552 put_page(page); 1553 if (!ret) { 1554 LIST_HEAD(pagelist); 1555 inc_zone_page_state(page, NR_ISOLATED_ANON + 1556 page_is_file_cache(page)); 1557 list_add(&page->lru, &pagelist); 1558 ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 1559 false, MIGRATE_SYNC); 1560 if (ret) { 1561 putback_lru_pages(&pagelist); 1562 pr_info("soft offline: %#lx: migration failed %d, type %lx\n", 1563 pfn, ret, page->flags); 1564 if (ret > 0) 1565 ret = -EIO; 1566 } 1567 } else { 1568 pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", 1569 pfn, ret, page_count(page), page->flags); 1570 } 1571 if (ret) 1572 return ret; 1573 1574 done: 1575 atomic_long_add(1, &mce_bad_pages); 1576 SetPageHWPoison(page); 1577 /* keep elevated page count for bad page */ 1578 return ret; 1579 } 1580