1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2008, 2009 Intel Corporation
4 * Authors: Andi Kleen, Fengguang Wu
6 * High level machine check handler. Handles pages reported by the
7 * hardware as being corrupted usually due to a multi-bit ECC memory or cache
10 * In addition there is a "soft offline" entry point that allows stop using
11 * not-yet-corrupted-by-suspicious pages without killing anything.
13 * Handles page cache pages in various states. The tricky part
14 * here is that we can access any page asynchronously in respect to
15 * other VM users, because memory failures could happen anytime and
16 * anywhere. This could violate some of their assumptions. This is why
17 * this code has to be extremely careful. Generally it tries to use
18 * normal locking rules, as in get the standard locks, even if that means
19 * the error handling takes potentially a long time.
21 * It can be very tempting to add handling for obscure cases here.
22 * In general any code for handling new cases should only be added iff:
23 * - You know how to test it.
24 * - You have a test that can be added to mce-test
25 * https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/
26 * - The case actually shows up as a frequent (top 10) page state in
27 * tools/vm/page-types when running a real workload.
29 * There are several operations here with exponential complexity because
30 * of unsuitable VM data structures. For example the operation to map back
31 * from RMAP chains to processes has to walk the complete process list and
32 * has non linear complexity with the number. But since memory corruptions
33 * are rare we hope to get away with this. This avoids impacting the core
36 #include <linux/kernel.h>
38 #include <linux/page-flags.h>
39 #include <linux/kernel-page-flags.h>
40 #include <linux/sched/signal.h>
41 #include <linux/sched/task.h>
42 #include <linux/ksm.h>
43 #include <linux/rmap.h>
44 #include <linux/export.h>
45 #include <linux/pagemap.h>
46 #include <linux/swap.h>
47 #include <linux/backing-dev.h>
48 #include <linux/migrate.h>
49 #include <linux/suspend.h>
50 #include <linux/slab.h>
51 #include <linux/swapops.h>
52 #include <linux/hugetlb.h>
53 #include <linux/memory_hotplug.h>
54 #include <linux/mm_inline.h>
55 #include <linux/memremap.h>
56 #include <linux/kfifo.h>
57 #include <linux/ratelimit.h>
58 #include <linux/page-isolation.h>
60 #include "ras/ras_event.h"
62 int sysctl_memory_failure_early_kill __read_mostly = 0;
64 int sysctl_memory_failure_recovery __read_mostly = 1;
66 atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
68 static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
70 if (hugepage_or_freepage) {
72 * Doing this check for free pages is also fine since dissolve_free_huge_page
73 * returns 0 for non-hugetlb pages as well.
75 if (dissolve_free_huge_page(page) || !take_page_off_buddy(page))
77 * We could fail to take off the target page from buddy
78 * for example due to racy page allocaiton, but that's
79 * acceptable because soft-offlined page is not broken
80 * and if someone really want to use it, they should
86 SetPageHWPoison(page);
90 num_poisoned_pages_inc();
95 #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
97 u32 hwpoison_filter_enable = 0;
98 u32 hwpoison_filter_dev_major = ~0U;
99 u32 hwpoison_filter_dev_minor = ~0U;
100 u64 hwpoison_filter_flags_mask;
101 u64 hwpoison_filter_flags_value;
102 EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
103 EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
104 EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
105 EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
106 EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
108 static int hwpoison_filter_dev(struct page *p)
110 struct address_space *mapping;
113 if (hwpoison_filter_dev_major == ~0U &&
114 hwpoison_filter_dev_minor == ~0U)
118 * page_mapping() does not accept slab pages.
123 mapping = page_mapping(p);
124 if (mapping == NULL || mapping->host == NULL)
127 dev = mapping->host->i_sb->s_dev;
128 if (hwpoison_filter_dev_major != ~0U &&
129 hwpoison_filter_dev_major != MAJOR(dev))
131 if (hwpoison_filter_dev_minor != ~0U &&
132 hwpoison_filter_dev_minor != MINOR(dev))
138 static int hwpoison_filter_flags(struct page *p)
140 if (!hwpoison_filter_flags_mask)
143 if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
144 hwpoison_filter_flags_value)
151 * This allows stress tests to limit test scope to a collection of tasks
152 * by putting them under some memcg. This prevents killing unrelated/important
153 * processes such as /sbin/init. Note that the target task may share clean
154 * pages with init (eg. libc text), which is harmless. If the target task
155 * share _dirty_ pages with another task B, the test scheme must make sure B
156 * is also included in the memcg. At last, due to race conditions this filter
157 * can only guarantee that the page either belongs to the memcg tasks, or is
161 u64 hwpoison_filter_memcg;
162 EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
163 static int hwpoison_filter_task(struct page *p)
165 if (!hwpoison_filter_memcg)
168 if (page_cgroup_ino(p) != hwpoison_filter_memcg)
174 static int hwpoison_filter_task(struct page *p) { return 0; }
177 int hwpoison_filter(struct page *p)
179 if (!hwpoison_filter_enable)
182 if (hwpoison_filter_dev(p))
185 if (hwpoison_filter_flags(p))
188 if (hwpoison_filter_task(p))
194 int hwpoison_filter(struct page *p)
200 EXPORT_SYMBOL_GPL(hwpoison_filter);
203 * Kill all processes that have a poisoned page mapped and then isolate
207 * Find all processes having the page mapped and kill them.
208 * But we keep a page reference around so that the page is not
209 * actually freed yet.
210 * Then stash the page away
212 * There's no convenient way to get back to mapped processes
213 * from the VMAs. So do a brute-force search over all
216 * Remember that machine checks are not common (or rather
217 * if they are common you have other problems), so this shouldn't
218 * be a performance issue.
220 * Also there are some races possible while we get from the
221 * error detection to actually handle it.
226 struct task_struct *tsk;
232 * Send all the processes who have the page mapped a signal.
233 * ``action optional'' if they are not immediately affected by the error
234 * ``action required'' if error happened in current execution context
236 static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
238 struct task_struct *t = tk->tsk;
239 short addr_lsb = tk->size_shift;
242 pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
243 pfn, t->comm, t->pid);
245 if (flags & MF_ACTION_REQUIRED) {
246 WARN_ON_ONCE(t != current);
247 ret = force_sig_mceerr(BUS_MCEERR_AR,
248 (void __user *)tk->addr, addr_lsb);
251 * Don't use force here, it's convenient if the signal
252 * can be temporarily blocked.
253 * This could cause a loop when the user sets SIGBUS
254 * to SIG_IGN, but hopefully no one will do that?
256 ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
257 addr_lsb, t); /* synchronous? */
260 pr_info("Memory failure: Error sending signal to %s:%d: %d\n",
261 t->comm, t->pid, ret);
266 * When a unknown page type is encountered drain as many buffers as possible
267 * in the hope to turn the page into a LRU or free page, which we can handle.
269 void shake_page(struct page *p, int access)
278 drain_all_pages(page_zone(p));
279 if (PageLRU(p) || is_free_buddy_page(p))
284 * Only call shrink_node_slabs here (which would also shrink
285 * other caches) if access is not potentially fatal.
288 drop_slab_node(page_to_nid(p));
290 EXPORT_SYMBOL_GPL(shake_page);
292 static unsigned long dev_pagemap_mapping_shift(struct page *page,
293 struct vm_area_struct *vma)
295 unsigned long address = vma_address(page, vma);
302 pgd = pgd_offset(vma->vm_mm, address);
303 if (!pgd_present(*pgd))
305 p4d = p4d_offset(pgd, address);
306 if (!p4d_present(*p4d))
308 pud = pud_offset(p4d, address);
309 if (!pud_present(*pud))
311 if (pud_devmap(*pud))
313 pmd = pmd_offset(pud, address);
314 if (!pmd_present(*pmd))
316 if (pmd_devmap(*pmd))
318 pte = pte_offset_map(pmd, address);
319 if (!pte_present(*pte))
321 if (pte_devmap(*pte))
327 * Failure handling: if we can't find or can't kill a process there's
328 * not much we can do. We just print a message and ignore otherwise.
332 * Schedule a process for later kill.
333 * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
335 static void add_to_kill(struct task_struct *tsk, struct page *p,
336 struct vm_area_struct *vma,
337 struct list_head *to_kill)
341 tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
343 pr_err("Memory failure: Out of memory while machine check handling\n");
347 tk->addr = page_address_in_vma(p, vma);
348 if (is_zone_device_page(p))
349 tk->size_shift = dev_pagemap_mapping_shift(p, vma);
351 tk->size_shift = page_shift(compound_head(p));
354 * Send SIGKILL if "tk->addr == -EFAULT". Also, as
355 * "tk->size_shift" is always non-zero for !is_zone_device_page(),
356 * so "tk->size_shift == 0" effectively checks no mapping on
357 * ZONE_DEVICE. Indeed, when a devdax page is mmapped N times
358 * to a process' address space, it's possible not all N VMAs
359 * contain mappings for the page, but at least one VMA does.
360 * Only deliver SIGBUS with payload derived from the VMA that
361 * has a mapping for the page.
363 if (tk->addr == -EFAULT) {
364 pr_info("Memory failure: Unable to find user space address %lx in %s\n",
365 page_to_pfn(p), tsk->comm);
366 } else if (tk->size_shift == 0) {
371 get_task_struct(tsk);
373 list_add_tail(&tk->nd, to_kill);
377 * Kill the processes that have been collected earlier.
379 * Only do anything when DOIT is set, otherwise just free the list
380 * (this is used for clean pages which do not need killing)
381 * Also when FAIL is set do a force kill because something went
384 static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
385 unsigned long pfn, int flags)
387 struct to_kill *tk, *next;
389 list_for_each_entry_safe (tk, next, to_kill, nd) {
392 * In case something went wrong with munmapping
393 * make sure the process doesn't catch the
394 * signal and then access the memory. Just kill it.
396 if (fail || tk->addr == -EFAULT) {
397 pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
398 pfn, tk->tsk->comm, tk->tsk->pid);
399 do_send_sig_info(SIGKILL, SEND_SIG_PRIV,
400 tk->tsk, PIDTYPE_PID);
404 * In theory the process could have mapped
405 * something else on the address in-between. We could
406 * check for that, but we need to tell the
409 else if (kill_proc(tk, pfn, flags) < 0)
410 pr_err("Memory failure: %#lx: Cannot send advisory machine check signal to %s:%d\n",
411 pfn, tk->tsk->comm, tk->tsk->pid);
413 put_task_struct(tk->tsk);
419 * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
420 * on behalf of the thread group. Return task_struct of the (first found)
421 * dedicated thread if found, and return NULL otherwise.
423 * We already hold read_lock(&tasklist_lock) in the caller, so we don't
424 * have to call rcu_read_lock/unlock() in this function.
426 static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
428 struct task_struct *t;
430 for_each_thread(tsk, t) {
431 if (t->flags & PF_MCE_PROCESS) {
432 if (t->flags & PF_MCE_EARLY)
435 if (sysctl_memory_failure_early_kill)
443 * Determine whether a given process is "early kill" process which expects
444 * to be signaled when some page under the process is hwpoisoned.
445 * Return task_struct of the dedicated thread (main thread unless explicitly
446 * specified) if the process is "early kill," and otherwise returns NULL.
448 * Note that the above is true for Action Optional case, but not for Action
449 * Required case where SIGBUS should sent only to the current thread.
451 static struct task_struct *task_early_kill(struct task_struct *tsk,
458 * Comparing ->mm here because current task might represent
459 * a subthread, while tsk always points to the main thread.
461 if (tsk->mm == current->mm)
466 return find_early_kill_thread(tsk);
470 * Collect processes when the error hit an anonymous page.
472 static void collect_procs_anon(struct page *page, struct list_head *to_kill,
475 struct vm_area_struct *vma;
476 struct task_struct *tsk;
480 av = page_lock_anon_vma_read(page);
481 if (av == NULL) /* Not actually mapped anymore */
484 pgoff = page_to_pgoff(page);
485 read_lock(&tasklist_lock);
486 for_each_process (tsk) {
487 struct anon_vma_chain *vmac;
488 struct task_struct *t = task_early_kill(tsk, force_early);
492 anon_vma_interval_tree_foreach(vmac, &av->rb_root,
495 if (!page_mapped_in_vma(page, vma))
497 if (vma->vm_mm == t->mm)
498 add_to_kill(t, page, vma, to_kill);
501 read_unlock(&tasklist_lock);
502 page_unlock_anon_vma_read(av);
506 * Collect processes when the error hit a file mapped page.
508 static void collect_procs_file(struct page *page, struct list_head *to_kill,
511 struct vm_area_struct *vma;
512 struct task_struct *tsk;
513 struct address_space *mapping = page->mapping;
516 i_mmap_lock_read(mapping);
517 read_lock(&tasklist_lock);
518 pgoff = page_to_pgoff(page);
519 for_each_process(tsk) {
520 struct task_struct *t = task_early_kill(tsk, force_early);
524 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
527 * Send early kill signal to tasks where a vma covers
528 * the page but the corrupted page is not necessarily
529 * mapped it in its pte.
530 * Assume applications who requested early kill want
531 * to be informed of all such data corruptions.
533 if (vma->vm_mm == t->mm)
534 add_to_kill(t, page, vma, to_kill);
537 read_unlock(&tasklist_lock);
538 i_mmap_unlock_read(mapping);
542 * Collect the processes who have the corrupted page mapped to kill.
544 static void collect_procs(struct page *page, struct list_head *tokill,
551 collect_procs_anon(page, tokill, force_early);
553 collect_procs_file(page, tokill, force_early);
556 static const char *action_name[] = {
557 [MF_IGNORED] = "Ignored",
558 [MF_FAILED] = "Failed",
559 [MF_DELAYED] = "Delayed",
560 [MF_RECOVERED] = "Recovered",
563 static const char * const action_page_types[] = {
564 [MF_MSG_KERNEL] = "reserved kernel page",
565 [MF_MSG_KERNEL_HIGH_ORDER] = "high-order kernel page",
566 [MF_MSG_SLAB] = "kernel slab page",
567 [MF_MSG_DIFFERENT_COMPOUND] = "different compound page after locking",
568 [MF_MSG_POISONED_HUGE] = "huge page already hardware poisoned",
569 [MF_MSG_HUGE] = "huge page",
570 [MF_MSG_FREE_HUGE] = "free huge page",
571 [MF_MSG_NON_PMD_HUGE] = "non-pmd-sized huge page",
572 [MF_MSG_UNMAP_FAILED] = "unmapping failed page",
573 [MF_MSG_DIRTY_SWAPCACHE] = "dirty swapcache page",
574 [MF_MSG_CLEAN_SWAPCACHE] = "clean swapcache page",
575 [MF_MSG_DIRTY_MLOCKED_LRU] = "dirty mlocked LRU page",
576 [MF_MSG_CLEAN_MLOCKED_LRU] = "clean mlocked LRU page",
577 [MF_MSG_DIRTY_UNEVICTABLE_LRU] = "dirty unevictable LRU page",
578 [MF_MSG_CLEAN_UNEVICTABLE_LRU] = "clean unevictable LRU page",
579 [MF_MSG_DIRTY_LRU] = "dirty LRU page",
580 [MF_MSG_CLEAN_LRU] = "clean LRU page",
581 [MF_MSG_TRUNCATED_LRU] = "already truncated LRU page",
582 [MF_MSG_BUDDY] = "free buddy page",
583 [MF_MSG_BUDDY_2ND] = "free buddy page (2nd try)",
584 [MF_MSG_DAX] = "dax page",
585 [MF_MSG_UNSPLIT_THP] = "unsplit thp",
586 [MF_MSG_UNKNOWN] = "unknown page",
590 * XXX: It is possible that a page is isolated from LRU cache,
591 * and then kept in swap cache or failed to remove from page cache.
592 * The page count will stop it from being freed by unpoison.
593 * Stress tests should be aware of this memory leak problem.
595 static int delete_from_lru_cache(struct page *p)
597 if (!isolate_lru_page(p)) {
599 * Clear sensible page flags, so that the buddy system won't
600 * complain when the page is unpoison-and-freed.
603 ClearPageUnevictable(p);
606 * Poisoned page might never drop its ref count to 0 so we have
607 * to uncharge it manually from its memcg.
609 mem_cgroup_uncharge(p);
612 * drop the page count elevated by isolate_lru_page()
620 static int truncate_error_page(struct page *p, unsigned long pfn,
621 struct address_space *mapping)
625 if (mapping->a_ops->error_remove_page) {
626 int err = mapping->a_ops->error_remove_page(mapping, p);
629 pr_info("Memory failure: %#lx: Failed to punch page: %d\n",
631 } else if (page_has_private(p) &&
632 !try_to_release_page(p, GFP_NOIO)) {
633 pr_info("Memory failure: %#lx: failed to release buffers\n",
640 * If the file system doesn't support it just invalidate
641 * This fails on dirty or anything with private pages
643 if (invalidate_inode_page(p))
646 pr_info("Memory failure: %#lx: Failed to invalidate\n",
654 * Error hit kernel page.
655 * Do nothing, try to be lucky and not touch this instead. For a few cases we
656 * could be more sophisticated.
658 static int me_kernel(struct page *p, unsigned long pfn)
664 * Page in unknown state. Do nothing.
666 static int me_unknown(struct page *p, unsigned long pfn)
668 pr_err("Memory failure: %#lx: Unknown page state\n", pfn);
673 * Clean (or cleaned) page cache page.
675 static int me_pagecache_clean(struct page *p, unsigned long pfn)
677 struct address_space *mapping;
679 delete_from_lru_cache(p);
682 * For anonymous pages we're done the only reference left
683 * should be the one m_f() holds.
689 * Now truncate the page in the page cache. This is really
690 * more like a "temporary hole punch"
691 * Don't do this for block devices when someone else
692 * has a reference, because it could be file system metadata
693 * and that's not safe to truncate.
695 mapping = page_mapping(p);
698 * Page has been teared down in the meanwhile
704 * Truncation is a bit tricky. Enable it per file system for now.
706 * Open: to take i_mutex or not for this? Right now we don't.
708 return truncate_error_page(p, pfn, mapping);
712 * Dirty pagecache page
713 * Issues: when the error hit a hole page the error is not properly
716 static int me_pagecache_dirty(struct page *p, unsigned long pfn)
718 struct address_space *mapping = page_mapping(p);
721 /* TBD: print more information about the file. */
724 * IO error will be reported by write(), fsync(), etc.
725 * who check the mapping.
726 * This way the application knows that something went
727 * wrong with its dirty file data.
729 * There's one open issue:
731 * The EIO will be only reported on the next IO
732 * operation and then cleared through the IO map.
733 * Normally Linux has two mechanisms to pass IO error
734 * first through the AS_EIO flag in the address space
735 * and then through the PageError flag in the page.
736 * Since we drop pages on memory failure handling the
737 * only mechanism open to use is through AS_AIO.
739 * This has the disadvantage that it gets cleared on
740 * the first operation that returns an error, while
741 * the PageError bit is more sticky and only cleared
742 * when the page is reread or dropped. If an
743 * application assumes it will always get error on
744 * fsync, but does other operations on the fd before
745 * and the page is dropped between then the error
746 * will not be properly reported.
748 * This can already happen even without hwpoisoned
749 * pages: first on metadata IO errors (which only
750 * report through AS_EIO) or when the page is dropped
753 * So right now we assume that the application DTRT on
754 * the first EIO, but we're not worse than other parts
757 mapping_set_error(mapping, -EIO);
760 return me_pagecache_clean(p, pfn);
764 * Clean and dirty swap cache.
766 * Dirty swap cache page is tricky to handle. The page could live both in page
767 * cache and swap cache(ie. page is freshly swapped in). So it could be
768 * referenced concurrently by 2 types of PTEs:
769 * normal PTEs and swap PTEs. We try to handle them consistently by calling
770 * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
772 * - clear dirty bit to prevent IO
774 * - but keep in the swap cache, so that when we return to it on
775 * a later page fault, we know the application is accessing
776 * corrupted data and shall be killed (we installed simple
777 * interception code in do_swap_page to catch it).
779 * Clean swap cache pages can be directly isolated. A later page fault will
780 * bring in the known good data from disk.
782 static int me_swapcache_dirty(struct page *p, unsigned long pfn)
785 /* Trigger EIO in shmem: */
786 ClearPageUptodate(p);
788 if (!delete_from_lru_cache(p))
794 static int me_swapcache_clean(struct page *p, unsigned long pfn)
796 delete_from_swap_cache(p);
798 if (!delete_from_lru_cache(p))
805 * Huge pages. Needs work.
807 * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
808 * To narrow down kill region to one page, we need to break up pmd.
810 static int me_huge_page(struct page *p, unsigned long pfn)
813 struct page *hpage = compound_head(p);
814 struct address_space *mapping;
816 if (!PageHuge(hpage))
819 mapping = page_mapping(hpage);
821 res = truncate_error_page(hpage, pfn, mapping);
825 * migration entry prevents later access on error anonymous
826 * hugepage, so we can free and dissolve it into buddy to
827 * save healthy subpages.
831 dissolve_free_huge_page(p);
840 * Various page states we can handle.
842 * A page state is defined by its current page->flags bits.
843 * The table matches them in order and calls the right handler.
845 * This is quite tricky because we can access page at any time
846 * in its live cycle, so all accesses have to be extremely careful.
848 * This is not complete. More states could be added.
849 * For any missing state don't attempt recovery.
852 #define dirty (1UL << PG_dirty)
853 #define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked))
854 #define unevict (1UL << PG_unevictable)
855 #define mlock (1UL << PG_mlocked)
856 #define lru (1UL << PG_lru)
857 #define head (1UL << PG_head)
858 #define slab (1UL << PG_slab)
859 #define reserved (1UL << PG_reserved)
861 static struct page_state {
864 enum mf_action_page_type type;
865 int (*action)(struct page *p, unsigned long pfn);
867 { reserved, reserved, MF_MSG_KERNEL, me_kernel },
869 * free pages are specially detected outside this table:
870 * PG_buddy pages only make a small fraction of all free pages.
874 * Could in theory check if slab page is free or if we can drop
875 * currently unused objects without touching them. But just
876 * treat it as standard kernel for now.
878 { slab, slab, MF_MSG_SLAB, me_kernel },
880 { head, head, MF_MSG_HUGE, me_huge_page },
882 { sc|dirty, sc|dirty, MF_MSG_DIRTY_SWAPCACHE, me_swapcache_dirty },
883 { sc|dirty, sc, MF_MSG_CLEAN_SWAPCACHE, me_swapcache_clean },
885 { mlock|dirty, mlock|dirty, MF_MSG_DIRTY_MLOCKED_LRU, me_pagecache_dirty },
886 { mlock|dirty, mlock, MF_MSG_CLEAN_MLOCKED_LRU, me_pagecache_clean },
888 { unevict|dirty, unevict|dirty, MF_MSG_DIRTY_UNEVICTABLE_LRU, me_pagecache_dirty },
889 { unevict|dirty, unevict, MF_MSG_CLEAN_UNEVICTABLE_LRU, me_pagecache_clean },
891 { lru|dirty, lru|dirty, MF_MSG_DIRTY_LRU, me_pagecache_dirty },
892 { lru|dirty, lru, MF_MSG_CLEAN_LRU, me_pagecache_clean },
895 * Catchall entry: must be at end.
897 { 0, 0, MF_MSG_UNKNOWN, me_unknown },
910 * "Dirty/Clean" indication is not 100% accurate due to the possibility of
911 * setting PG_dirty outside page lock. See also comment above set_page_dirty().
913 static void action_result(unsigned long pfn, enum mf_action_page_type type,
914 enum mf_result result)
916 trace_memory_failure_event(pfn, type, result);
918 pr_err("Memory failure: %#lx: recovery action for %s: %s\n",
919 pfn, action_page_types[type], action_name[result]);
922 static int page_action(struct page_state *ps, struct page *p,
928 result = ps->action(p, pfn);
930 count = page_count(p) - 1;
931 if (ps->action == me_swapcache_dirty && result == MF_DELAYED)
934 pr_err("Memory failure: %#lx: %s still referenced by %d users\n",
935 pfn, action_page_types[ps->type], count);
938 action_result(pfn, ps->type, result);
940 /* Could do more checks here if page looks ok */
942 * Could adjust zone counters here to correct for the missing page.
945 return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
949 * get_hwpoison_page() - Get refcount for memory error handling:
950 * @page: raw error page (hit by memory error)
952 * Return: return 0 if failed to grab the refcount, otherwise true (some
955 static int get_hwpoison_page(struct page *page)
957 struct page *head = compound_head(page);
959 if (!PageHuge(head) && PageTransHuge(head)) {
961 * Non anonymous thp exists only in allocation/free time. We
962 * can't handle such a case correctly, so let's give it up.
963 * This should be better than triggering BUG_ON when kernel
964 * tries to touch the "partially handled" page.
966 if (!PageAnon(head)) {
967 pr_err("Memory failure: %#lx: non anonymous thp\n",
973 if (get_page_unless_zero(head)) {
974 if (head == compound_head(page))
977 pr_info("Memory failure: %#lx cannot catch tail\n",
986 * Do all that is necessary to remove user space mappings. Unmap
987 * the pages and send SIGBUS to the processes if the data was dirty.
989 static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
990 int flags, struct page **hpagep)
992 enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
993 struct address_space *mapping;
995 bool unmap_success = true;
996 int kill = 1, forcekill;
997 struct page *hpage = *hpagep;
998 bool mlocked = PageMlocked(hpage);
1001 * Here we are interested only in user-mapped pages, so skip any
1002 * other types of pages.
1004 if (PageReserved(p) || PageSlab(p))
1006 if (!(PageLRU(hpage) || PageHuge(p)))
1010 * This check implies we don't kill processes if their pages
1011 * are in the swap cache early. Those are always late kills.
1013 if (!page_mapped(hpage))
1017 pr_err("Memory failure: %#lx: can't handle KSM pages.\n", pfn);
1021 if (PageSwapCache(p)) {
1022 pr_err("Memory failure: %#lx: keeping poisoned page in swap cache\n",
1024 ttu |= TTU_IGNORE_HWPOISON;
1028 * Propagate the dirty bit from PTEs to struct page first, because we
1029 * need this to decide if we should kill or just drop the page.
1030 * XXX: the dirty test could be racy: set_page_dirty() may not always
1031 * be called inside page lock (it's recommended but not enforced).
1033 mapping = page_mapping(hpage);
1034 if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
1035 mapping_can_writeback(mapping)) {
1036 if (page_mkclean(hpage)) {
1037 SetPageDirty(hpage);
1040 ttu |= TTU_IGNORE_HWPOISON;
1041 pr_info("Memory failure: %#lx: corrupted page was clean: dropped without side effects\n",
1047 * First collect all the processes that have the page
1048 * mapped in dirty form. This has to be done before try_to_unmap,
1049 * because ttu takes the rmap data structures down.
1051 * Error handling: We ignore errors here because
1052 * there's nothing that can be done.
1055 collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
1057 if (!PageHuge(hpage)) {
1058 unmap_success = try_to_unmap(hpage, ttu);
1060 if (!PageAnon(hpage)) {
1062 * For hugetlb pages in shared mappings, try_to_unmap
1063 * could potentially call huge_pmd_unshare. Because of
1064 * this, take semaphore in write mode here and set
1065 * TTU_RMAP_LOCKED to indicate we have taken the lock
1066 * at this higer level.
1068 mapping = hugetlb_page_mapping_lock_write(hpage);
1070 unmap_success = try_to_unmap(hpage,
1071 ttu|TTU_RMAP_LOCKED);
1072 i_mmap_unlock_write(mapping);
1074 pr_info("Memory failure: %#lx: could not lock mapping for mapped huge page\n", pfn);
1075 unmap_success = false;
1078 unmap_success = try_to_unmap(hpage, ttu);
1082 pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n",
1083 pfn, page_mapcount(hpage));
1086 * try_to_unmap() might put mlocked page in lru cache, so call
1087 * shake_page() again to ensure that it's flushed.
1090 shake_page(hpage, 0);
1093 * Now that the dirty bit has been propagated to the
1094 * struct page and all unmaps done we can decide if
1095 * killing is needed or not. Only kill when the page
1096 * was dirty or the process is not restartable,
1097 * otherwise the tokill list is merely
1098 * freed. When there was a problem unmapping earlier
1099 * use a more force-full uncatchable kill to prevent
1100 * any accesses to the poisoned memory.
1102 forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
1103 kill_procs(&tokill, forcekill, !unmap_success, pfn, flags);
1105 return unmap_success;
1108 static int identify_page_state(unsigned long pfn, struct page *p,
1109 unsigned long page_flags)
1111 struct page_state *ps;
1114 * The first check uses the current page flags which may not have any
1115 * relevant information. The second check with the saved page flags is
1116 * carried out only if the first check can't determine the page status.
1118 for (ps = error_states;; ps++)
1119 if ((p->flags & ps->mask) == ps->res)
1122 page_flags |= (p->flags & (1UL << PG_dirty));
1125 for (ps = error_states;; ps++)
1126 if ((page_flags & ps->mask) == ps->res)
1128 return page_action(ps, p, pfn);
1131 static int try_to_split_thp_page(struct page *page, const char *msg)
1134 if (!PageAnon(page) || unlikely(split_huge_page(page))) {
1135 unsigned long pfn = page_to_pfn(page);
1138 if (!PageAnon(page))
1139 pr_info("%s: %#lx: non anonymous thp\n", msg, pfn);
1141 pr_info("%s: %#lx: thp split failed\n", msg, pfn);
1150 static int memory_failure_hugetlb(unsigned long pfn, int flags)
1152 struct page *p = pfn_to_page(pfn);
1153 struct page *head = compound_head(p);
1155 unsigned long page_flags;
1157 if (TestSetPageHWPoison(head)) {
1158 pr_err("Memory failure: %#lx: already hardware poisoned\n",
1163 num_poisoned_pages_inc();
1165 if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
1167 * Check "filter hit" and "race with other subpage."
1170 if (PageHWPoison(head)) {
1171 if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
1172 || (p != head && TestSetPageHWPoison(head))) {
1173 num_poisoned_pages_dec();
1179 dissolve_free_huge_page(p);
1180 action_result(pfn, MF_MSG_FREE_HUGE, MF_DELAYED);
1185 page_flags = head->flags;
1187 if (!PageHWPoison(head)) {
1188 pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
1189 num_poisoned_pages_dec();
1196 * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so
1197 * simply disable it. In order to make it work properly, we need
1199 * - conversion of a pud that maps an error hugetlb into hwpoison
1200 * entry properly works, and
1201 * - other mm code walking over page table is aware of pud-aligned
1204 if (huge_page_size(page_hstate(head)) > PMD_SIZE) {
1205 action_result(pfn, MF_MSG_NON_PMD_HUGE, MF_IGNORED);
1210 if (!hwpoison_user_mappings(p, pfn, flags, &head)) {
1211 action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
1216 res = identify_page_state(pfn, p, page_flags);
1222 static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
1223 struct dev_pagemap *pgmap)
1225 struct page *page = pfn_to_page(pfn);
1226 const bool unmap_success = true;
1227 unsigned long size = 0;
1235 * Prevent the inode from being freed while we are interrogating
1236 * the address_space, typically this would be handled by
1237 * lock_page(), but dax pages do not use the page lock. This
1238 * also prevents changes to the mapping of this pfn until
1239 * poison signaling is complete.
1241 cookie = dax_lock_page(page);
1245 if (hwpoison_filter(page)) {
1250 if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
1252 * TODO: Handle HMM pages which may need coordination
1253 * with device-side memory.
1259 * Use this flag as an indication that the dax page has been
1260 * remapped UC to prevent speculative consumption of poison.
1262 SetPageHWPoison(page);
1265 * Unlike System-RAM there is no possibility to swap in a
1266 * different physical page at a given virtual address, so all
1267 * userspace consumption of ZONE_DEVICE memory necessitates
1268 * SIGBUS (i.e. MF_MUST_KILL)
1270 flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
1271 collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED);
1273 list_for_each_entry(tk, &tokill, nd)
1275 size = max(size, 1UL << tk->size_shift);
1278 * Unmap the largest mapping to avoid breaking up
1279 * device-dax mappings which are constant size. The
1280 * actual size of the mapping being torn down is
1281 * communicated in siginfo, see kill_proc()
1283 start = (page->index << PAGE_SHIFT) & ~(size - 1);
1284 unmap_mapping_range(page->mapping, start, start + size, 0);
1286 kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, pfn, flags);
1289 dax_unlock_page(page, cookie);
1291 /* drop pgmap ref acquired in caller */
1292 put_dev_pagemap(pgmap);
1293 action_result(pfn, MF_MSG_DAX, rc ? MF_FAILED : MF_RECOVERED);
1298 * memory_failure - Handle memory failure of a page.
1299 * @pfn: Page Number of the corrupted page
1300 * @flags: fine tune action taken
1302 * This function is called by the low level machine check code
1303 * of an architecture when it detects hardware memory corruption
1304 * of a page. It tries its best to recover, which includes
1305 * dropping pages, killing processes etc.
1307 * The function is primarily of use for corruptions that
1308 * happen outside the current execution context (e.g. when
1309 * detected by a background scrubber)
1311 * Must run in process context (e.g. a work queue) with interrupts
1312 * enabled and no spinlocks hold.
1314 int memory_failure(unsigned long pfn, int flags)
1318 struct page *orig_head;
1319 struct dev_pagemap *pgmap;
1321 unsigned long page_flags;
1323 if (!sysctl_memory_failure_recovery)
1324 panic("Memory failure on page %lx", pfn);
1326 p = pfn_to_online_page(pfn);
1328 if (pfn_valid(pfn)) {
1329 pgmap = get_dev_pagemap(pfn, NULL);
1331 return memory_failure_dev_pagemap(pfn, flags,
1334 pr_err("Memory failure: %#lx: memory outside kernel control\n",
1340 return memory_failure_hugetlb(pfn, flags);
1341 if (TestSetPageHWPoison(p)) {
1342 pr_err("Memory failure: %#lx: already hardware poisoned\n",
1347 orig_head = hpage = compound_head(p);
1348 num_poisoned_pages_inc();
1351 * We need/can do nothing about count=0 pages.
1352 * 1) it's a free page, and therefore in safe hand:
1353 * prep_new_page() will be the gate keeper.
1354 * 2) it's part of a non-compound high order page.
1355 * Implies some kernel user: cannot stop them from
1356 * R/W the page; let's pray that the page has been
1357 * used and will be freed some time later.
1358 * In fact it's dangerous to directly bump up page count from 0,
1359 * that may make page_ref_freeze()/page_ref_unfreeze() mismatch.
1361 if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
1362 if (is_free_buddy_page(p)) {
1363 action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
1366 action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
1371 if (PageTransHuge(hpage)) {
1372 if (try_to_split_thp_page(p, "Memory Failure") < 0) {
1373 action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
1376 VM_BUG_ON_PAGE(!page_count(p), p);
1380 * We ignore non-LRU pages for good reasons.
1381 * - PG_locked is only well defined for LRU pages and a few others
1382 * - to avoid races with __SetPageLocked()
1383 * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
1384 * The check (unnecessarily) ignores LRU pages being isolated and
1385 * walked by the page reclaim code, however that's not a big loss.
1388 /* shake_page could have turned it free. */
1389 if (!PageLRU(p) && is_free_buddy_page(p)) {
1390 if (flags & MF_COUNT_INCREASED)
1391 action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
1393 action_result(pfn, MF_MSG_BUDDY_2ND, MF_DELAYED);
1400 * The page could have changed compound pages during the locking.
1401 * If this happens just bail out.
1403 if (PageCompound(p) && compound_head(p) != orig_head) {
1404 action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
1410 * We use page flags to determine what action should be taken, but
1411 * the flags can be modified by the error containment action. One
1412 * example is an mlocked page, where PG_mlocked is cleared by
1413 * page_remove_rmap() in try_to_unmap_one(). So to determine page status
1414 * correctly, we save a copy of the page flags at this time.
1416 page_flags = p->flags;
1419 * unpoison always clear PG_hwpoison inside page lock
1421 if (!PageHWPoison(p)) {
1422 pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
1423 num_poisoned_pages_dec();
1428 if (hwpoison_filter(p)) {
1429 if (TestClearPageHWPoison(p))
1430 num_poisoned_pages_dec();
1436 if (!PageTransTail(p) && !PageLRU(p))
1437 goto identify_page_state;
1440 * It's very difficult to mess with pages currently under IO
1441 * and in many cases impossible, so we just avoid it here.
1443 wait_on_page_writeback(p);
1446 * Now take care of user space mappings.
1447 * Abort on fail: __delete_from_page_cache() assumes unmapped page.
1449 if (!hwpoison_user_mappings(p, pfn, flags, &p)) {
1450 action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
1456 * Torn down by someone else?
1458 if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
1459 action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
1464 identify_page_state:
1465 res = identify_page_state(pfn, p, page_flags);
1470 EXPORT_SYMBOL_GPL(memory_failure);
1472 #define MEMORY_FAILURE_FIFO_ORDER 4
1473 #define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER)
1475 struct memory_failure_entry {
1480 struct memory_failure_cpu {
1481 DECLARE_KFIFO(fifo, struct memory_failure_entry,
1482 MEMORY_FAILURE_FIFO_SIZE);
1484 struct work_struct work;
1487 static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);
1490 * memory_failure_queue - Schedule handling memory failure of a page.
1491 * @pfn: Page Number of the corrupted page
1492 * @flags: Flags for memory failure handling
1494 * This function is called by the low level hardware error handler
1495 * when it detects hardware memory corruption of a page. It schedules
1496 * the recovering of error page, including dropping pages, killing
1499 * The function is primarily of use for corruptions that
1500 * happen outside the current execution context (e.g. when
1501 * detected by a background scrubber)
1503 * Can run in IRQ context.
1505 void memory_failure_queue(unsigned long pfn, int flags)
1507 struct memory_failure_cpu *mf_cpu;
1508 unsigned long proc_flags;
1509 struct memory_failure_entry entry = {
1514 mf_cpu = &get_cpu_var(memory_failure_cpu);
1515 spin_lock_irqsave(&mf_cpu->lock, proc_flags);
1516 if (kfifo_put(&mf_cpu->fifo, entry))
1517 schedule_work_on(smp_processor_id(), &mf_cpu->work);
1519 pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n",
1521 spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
1522 put_cpu_var(memory_failure_cpu);
1524 EXPORT_SYMBOL_GPL(memory_failure_queue);
1526 static void memory_failure_work_func(struct work_struct *work)
1528 struct memory_failure_cpu *mf_cpu;
1529 struct memory_failure_entry entry = { 0, };
1530 unsigned long proc_flags;
1533 mf_cpu = container_of(work, struct memory_failure_cpu, work);
1535 spin_lock_irqsave(&mf_cpu->lock, proc_flags);
1536 gotten = kfifo_get(&mf_cpu->fifo, &entry);
1537 spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
1540 if (entry.flags & MF_SOFT_OFFLINE)
1541 soft_offline_page(entry.pfn, entry.flags);
1543 memory_failure(entry.pfn, entry.flags);
1548 * Process memory_failure work queued on the specified CPU.
1549 * Used to avoid return-to-userspace racing with the memory_failure workqueue.
1551 void memory_failure_queue_kick(int cpu)
1553 struct memory_failure_cpu *mf_cpu;
1555 mf_cpu = &per_cpu(memory_failure_cpu, cpu);
1556 cancel_work_sync(&mf_cpu->work);
1557 memory_failure_work_func(&mf_cpu->work);
1560 static int __init memory_failure_init(void)
1562 struct memory_failure_cpu *mf_cpu;
1565 for_each_possible_cpu(cpu) {
1566 mf_cpu = &per_cpu(memory_failure_cpu, cpu);
1567 spin_lock_init(&mf_cpu->lock);
1568 INIT_KFIFO(mf_cpu->fifo);
1569 INIT_WORK(&mf_cpu->work, memory_failure_work_func);
1574 core_initcall(memory_failure_init);
1576 #define unpoison_pr_info(fmt, pfn, rs) \
1578 if (__ratelimit(rs)) \
1579 pr_info(fmt, pfn); \
1583 * unpoison_memory - Unpoison a previously poisoned page
1584 * @pfn: Page number of the to be unpoisoned page
1586 * Software-unpoison a page that has been poisoned by
1587 * memory_failure() earlier.
1589 * This is only done on the software-level, so it only works
1590 * for linux injected failures, not real hardware failures
1592 * Returns 0 for success, otherwise -errno.
1594 int unpoison_memory(unsigned long pfn)
1599 static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
1600 DEFAULT_RATELIMIT_BURST);
1602 if (!pfn_valid(pfn))
1605 p = pfn_to_page(pfn);
1606 page = compound_head(p);
1608 if (!PageHWPoison(p)) {
1609 unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n",
1614 if (page_count(page) > 1) {
1615 unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n",
1620 if (page_mapped(page)) {
1621 unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n",
1626 if (page_mapping(page)) {
1627 unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n",
1633 * unpoison_memory() can encounter thp only when the thp is being
1634 * worked by memory_failure() and the page lock is not held yet.
1635 * In such case, we yield to memory_failure() and make unpoison fail.
1637 if (!PageHuge(page) && PageTransHuge(page)) {
1638 unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n",
1643 if (!get_hwpoison_page(p)) {
1644 if (TestClearPageHWPoison(p))
1645 num_poisoned_pages_dec();
1646 unpoison_pr_info("Unpoison: Software-unpoisoned free page %#lx\n",
1653 * This test is racy because PG_hwpoison is set outside of page lock.
1654 * That's acceptable because that won't trigger kernel panic. Instead,
1655 * the PG_hwpoison page will be caught and isolated on the entrance to
1656 * the free buddy page pool.
1658 if (TestClearPageHWPoison(page)) {
1659 unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
1661 num_poisoned_pages_dec();
1667 if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1))
1672 EXPORT_SYMBOL(unpoison_memory);
1675 * Safely get reference count of an arbitrary page.
1676 * Returns 0 for a free page, -EIO for a zero refcount page
1677 * that is not free, and 1 for any other page type.
1678 * For 1 the page is returned with increased page count, otherwise not.
1680 static int __get_any_page(struct page *p, unsigned long pfn, int flags)
1684 if (flags & MF_COUNT_INCREASED)
1688 * When the target page is a free hugepage, just remove it
1689 * from free hugepage list.
1691 if (!get_hwpoison_page(p)) {
1693 pr_info("%s: %#lx free huge page\n", __func__, pfn);
1695 } else if (is_free_buddy_page(p)) {
1696 pr_info("%s: %#lx free buddy page\n", __func__, pfn);
1698 } else if (page_count(p)) {
1699 /* raced with allocation */
1702 pr_info("%s: %#lx: unknown zero refcount page type %lx\n",
1703 __func__, pfn, p->flags);
1707 /* Not a free page */
1713 static int get_any_page(struct page *page, unsigned long pfn, int flags)
1715 int ret = __get_any_page(page, pfn, flags);
1718 ret = __get_any_page(page, pfn, flags);
1720 if (ret == 1 && !PageHuge(page) &&
1721 !PageLRU(page) && !__PageMovable(page)) {
1726 shake_page(page, 1);
1731 ret = __get_any_page(page, pfn, 0);
1732 if (ret == 1 && !PageLRU(page)) {
1733 /* Drop page reference which is from __get_any_page() */
1735 pr_info("soft_offline: %#lx: unknown non LRU page type %lx (%pGp)\n",
1736 pfn, page->flags, &page->flags);
1743 static bool isolate_page(struct page *page, struct list_head *pagelist)
1745 bool isolated = false;
1746 bool lru = PageLRU(page);
1748 if (PageHuge(page)) {
1749 isolated = isolate_huge_page(page, pagelist);
1752 isolated = !isolate_lru_page(page);
1754 isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
1757 list_add(&page->lru, pagelist);
1760 if (isolated && lru)
1761 inc_node_page_state(page, NR_ISOLATED_ANON +
1762 page_is_file_lru(page));
1765 * If we succeed to isolate the page, we grabbed another refcount on
1766 * the page, so we can safely drop the one we got from get_any_pages().
1767 * If we failed to isolate the page, it means that we cannot go further
1768 * and we will return an error, so drop the reference we got from
1769 * get_any_pages() as well.
1776 * __soft_offline_page handles hugetlb-pages and non-hugetlb pages.
1777 * If the page is a non-dirty unmapped page-cache page, it simply invalidates.
1778 * If the page is mapped, it migrates the contents over.
1780 static int __soft_offline_page(struct page *page)
1783 unsigned long pfn = page_to_pfn(page);
1784 struct page *hpage = compound_head(page);
1785 char const *msg_page[] = {"page", "hugepage"};
1786 bool huge = PageHuge(page);
1787 LIST_HEAD(pagelist);
1788 struct migration_target_control mtc = {
1789 .nid = NUMA_NO_NODE,
1790 .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
1794 * Check PageHWPoison again inside page lock because PageHWPoison
1795 * is set by memory_failure() outside page lock. Note that
1796 * memory_failure() also double-checks PageHWPoison inside page lock,
1797 * so there's no race between soft_offline_page() and memory_failure().
1800 if (!PageHuge(page))
1801 wait_on_page_writeback(page);
1802 if (PageHWPoison(page)) {
1805 pr_info("soft offline: %#lx page already poisoned\n", pfn);
1809 if (!PageHuge(page))
1811 * Try to invalidate first. This should work for
1812 * non dirty unmapped page cache pages.
1814 ret = invalidate_inode_page(page);
1818 * RED-PEN would be better to keep it isolated here, but we
1819 * would need to fix isolation locking first.
1822 pr_info("soft_offline: %#lx: invalidated\n", pfn);
1823 page_handle_poison(page, false, true);
1827 if (isolate_page(hpage, &pagelist)) {
1828 ret = migrate_pages(&pagelist, alloc_migration_target, NULL,
1829 (unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_FAILURE);
1831 bool release = !huge;
1833 if (!page_handle_poison(page, huge, release))
1836 if (!list_empty(&pagelist))
1837 putback_movable_pages(&pagelist);
1839 pr_info("soft offline: %#lx: %s migration failed %d, type %lx (%pGp)\n",
1840 pfn, msg_page[huge], ret, page->flags, &page->flags);
1845 pr_info("soft offline: %#lx: %s isolation failed: %d, page count %d, type %lx (%pGp)\n",
1846 pfn, msg_page[huge], ret, page_count(page), page->flags, &page->flags);
1852 static int soft_offline_in_use_page(struct page *page)
1854 struct page *hpage = compound_head(page);
1856 if (!PageHuge(page) && PageTransHuge(hpage))
1857 if (try_to_split_thp_page(page, "soft offline") < 0)
1859 return __soft_offline_page(page);
1862 static int soft_offline_free_page(struct page *page)
1866 if (!page_handle_poison(page, true, false))
1873 * soft_offline_page - Soft offline a page.
1874 * @pfn: pfn to soft-offline
1875 * @flags: flags. Same as memory_failure().
1877 * Returns 0 on success, otherwise negated errno.
1879 * Soft offline a page, by migration or invalidation,
1880 * without killing anything. This is for the case when
1881 * a page is not corrupted yet (so it's still valid to access),
1882 * but has had a number of corrected errors and is better taken
1885 * The actual policy on when to do that is maintained by
1888 * This should never impact any application or cause data loss,
1889 * however it might take some time.
1891 * This is not a 100% solution for all memory, but tries to be
1892 * ``good enough'' for the majority of memory.
1894 int soft_offline_page(unsigned long pfn, int flags)
1898 bool try_again = true;
1900 if (!pfn_valid(pfn))
1902 /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
1903 page = pfn_to_online_page(pfn);
1907 if (PageHWPoison(page)) {
1908 pr_info("soft offline: %#lx page already poisoned\n", pfn);
1909 if (flags & MF_COUNT_INCREASED)
1916 ret = get_any_page(page, pfn, flags);
1920 ret = soft_offline_in_use_page(page);
1922 if (soft_offline_free_page(page) && try_again) {