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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2008, 2009 Intel Corporation4 * Authors: Andi Kleen, Fengguang Wu5 *6 * High level machine check handler. Handles pages reported by the7 * hardware as being corrupted usually due to a multi-bit ECC memory or cache8 * failure.9 *10 * In addition there is a "soft offline" entry point that allows stop using11 * not-yet-corrupted-by-suspicious pages without killing anything.12 *13 * Handles page cache pages in various states. The tricky part14 * here is that we can access any page asynchronously in respect to15 * other VM users, because memory failures could happen anytime and16 * anywhere. This could violate some of their assumptions. This is why17 * this code has to be extremely careful. Generally it tries to use18 * normal locking rules, as in get the standard locks, even if that means19 * the error handling takes potentially a long time.20 *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-test25 * https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/26 * - The case actually shows up as a frequent (top 10) page state in27 * tools/mm/page-types when running a real workload.28 *29 * There are several operations here with exponential complexity because30 * of unsuitable VM data structures. For example the operation to map back31 * from RMAP chains to processes has to walk the complete process list and32 * has non linear complexity with the number. But since memory corruptions33 * are rare we hope to get away with this. This avoids impacting the core34 * VM.35 */36 37#define pr_fmt(fmt) "Memory failure: " fmt38 39#include <linux/kernel.h>40#include <linux/mm.h>41#include <linux/page-flags.h>42#include <linux/sched/signal.h>43#include <linux/sched/task.h>44#include <linux/dax.h>45#include <linux/ksm.h>46#include <linux/rmap.h>47#include <linux/export.h>48#include <linux/pagemap.h>49#include <linux/swap.h>50#include <linux/backing-dev.h>51#include <linux/migrate.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/memremap.h>58#include <linux/kfifo.h>59#include <linux/ratelimit.h>60#include <linux/pagewalk.h>61#include <linux/shmem_fs.h>62#include <linux/sysctl.h>63#include "swap.h"64#include "internal.h"65#include "ras/ras_event.h"66 67static int sysctl_memory_failure_early_kill __read_mostly;68 69static int sysctl_memory_failure_recovery __read_mostly = 1;70 71static int sysctl_enable_soft_offline __read_mostly = 1;72 73atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);74 75static bool hw_memory_failure __read_mostly = false;76 77static DEFINE_MUTEX(mf_mutex);78 79void num_poisoned_pages_inc(unsigned long pfn)80{81 atomic_long_inc(&num_poisoned_pages);82 memblk_nr_poison_inc(pfn);83}84 85void num_poisoned_pages_sub(unsigned long pfn, long i)86{87 atomic_long_sub(i, &num_poisoned_pages);88 if (pfn != -1UL)89 memblk_nr_poison_sub(pfn, i);90}91 92/**93 * MF_ATTR_RO - Create sysfs entry for each memory failure statistics.94 * @_name: name of the file in the per NUMA sysfs directory.95 */96#define MF_ATTR_RO(_name) \97static ssize_t _name##_show(struct device *dev, \98 struct device_attribute *attr, \99 char *buf) \100{ \101 struct memory_failure_stats *mf_stats = \102 &NODE_DATA(dev->id)->mf_stats; \103 return sprintf(buf, "%lu\n", mf_stats->_name); \104} \105static DEVICE_ATTR_RO(_name)106 107MF_ATTR_RO(total);108MF_ATTR_RO(ignored);109MF_ATTR_RO(failed);110MF_ATTR_RO(delayed);111MF_ATTR_RO(recovered);112 113static struct attribute *memory_failure_attr[] = {114 &dev_attr_total.attr,115 &dev_attr_ignored.attr,116 &dev_attr_failed.attr,117 &dev_attr_delayed.attr,118 &dev_attr_recovered.attr,119 NULL,120};121 122const struct attribute_group memory_failure_attr_group = {123 .name = "memory_failure",124 .attrs = memory_failure_attr,125};126 127static struct ctl_table memory_failure_table[] = {128 {129 .procname = "memory_failure_early_kill",130 .data = &sysctl_memory_failure_early_kill,131 .maxlen = sizeof(sysctl_memory_failure_early_kill),132 .mode = 0644,133 .proc_handler = proc_dointvec_minmax,134 .extra1 = SYSCTL_ZERO,135 .extra2 = SYSCTL_ONE,136 },137 {138 .procname = "memory_failure_recovery",139 .data = &sysctl_memory_failure_recovery,140 .maxlen = sizeof(sysctl_memory_failure_recovery),141 .mode = 0644,142 .proc_handler = proc_dointvec_minmax,143 .extra1 = SYSCTL_ZERO,144 .extra2 = SYSCTL_ONE,145 },146 {147 .procname = "enable_soft_offline",148 .data = &sysctl_enable_soft_offline,149 .maxlen = sizeof(sysctl_enable_soft_offline),150 .mode = 0644,151 .proc_handler = proc_dointvec_minmax,152 .extra1 = SYSCTL_ZERO,153 .extra2 = SYSCTL_ONE,154 }155};156 157/*158 * Return values:159 * 1: the page is dissolved (if needed) and taken off from buddy,160 * 0: the page is dissolved (if needed) and not taken off from buddy,161 * < 0: failed to dissolve.162 */163static int __page_handle_poison(struct page *page)164{165 int ret;166 167 /*168 * zone_pcp_disable() can't be used here. It will169 * hold pcp_batch_high_lock and dissolve_free_hugetlb_folio() might hold170 * cpu_hotplug_lock via static_key_slow_dec() when hugetlb vmemmap171 * optimization is enabled. This will break current lock dependency172 * chain and leads to deadlock.173 * Disabling pcp before dissolving the page was a deterministic174 * approach because we made sure that those pages cannot end up in any175 * PCP list. Draining PCP lists expels those pages to the buddy system,176 * but nothing guarantees that those pages do not get back to a PCP177 * queue if we need to refill those.178 */179 ret = dissolve_free_hugetlb_folio(page_folio(page));180 if (!ret) {181 drain_all_pages(page_zone(page));182 ret = take_page_off_buddy(page);183 }184 185 return ret;186}187 188static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)189{190 if (hugepage_or_freepage) {191 /*192 * Doing this check for free pages is also fine since193 * dissolve_free_hugetlb_folio() returns 0 for non-hugetlb folios as well.194 */195 if (__page_handle_poison(page) <= 0)196 /*197 * We could fail to take off the target page from buddy198 * for example due to racy page allocation, but that's199 * acceptable because soft-offlined page is not broken200 * and if someone really want to use it, they should201 * take it.202 */203 return false;204 }205 206 SetPageHWPoison(page);207 if (release)208 put_page(page);209 page_ref_inc(page);210 num_poisoned_pages_inc(page_to_pfn(page));211 212 return true;213}214 215#if IS_ENABLED(CONFIG_HWPOISON_INJECT)216 217u32 hwpoison_filter_enable = 0;218u32 hwpoison_filter_dev_major = ~0U;219u32 hwpoison_filter_dev_minor = ~0U;220u64 hwpoison_filter_flags_mask;221u64 hwpoison_filter_flags_value;222EXPORT_SYMBOL_GPL(hwpoison_filter_enable);223EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);224EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);225EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);226EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);227 228static int hwpoison_filter_dev(struct page *p)229{230 struct folio *folio = page_folio(p);231 struct address_space *mapping;232 dev_t dev;233 234 if (hwpoison_filter_dev_major == ~0U &&235 hwpoison_filter_dev_minor == ~0U)236 return 0;237 238 mapping = folio_mapping(folio);239 if (mapping == NULL || mapping->host == NULL)240 return -EINVAL;241 242 dev = mapping->host->i_sb->s_dev;243 if (hwpoison_filter_dev_major != ~0U &&244 hwpoison_filter_dev_major != MAJOR(dev))245 return -EINVAL;246 if (hwpoison_filter_dev_minor != ~0U &&247 hwpoison_filter_dev_minor != MINOR(dev))248 return -EINVAL;249 250 return 0;251}252 253static int hwpoison_filter_flags(struct page *p)254{255 if (!hwpoison_filter_flags_mask)256 return 0;257 258 if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==259 hwpoison_filter_flags_value)260 return 0;261 else262 return -EINVAL;263}264 265/*266 * This allows stress tests to limit test scope to a collection of tasks267 * by putting them under some memcg. This prevents killing unrelated/important268 * processes such as /sbin/init. Note that the target task may share clean269 * pages with init (eg. libc text), which is harmless. If the target task270 * share _dirty_ pages with another task B, the test scheme must make sure B271 * is also included in the memcg. At last, due to race conditions this filter272 * can only guarantee that the page either belongs to the memcg tasks, or is273 * a freed page.274 */275#ifdef CONFIG_MEMCG276u64 hwpoison_filter_memcg;277EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);278static int hwpoison_filter_task(struct page *p)279{280 if (!hwpoison_filter_memcg)281 return 0;282 283 if (page_cgroup_ino(p) != hwpoison_filter_memcg)284 return -EINVAL;285 286 return 0;287}288#else289static int hwpoison_filter_task(struct page *p) { return 0; }290#endif291 292int hwpoison_filter(struct page *p)293{294 if (!hwpoison_filter_enable)295 return 0;296 297 if (hwpoison_filter_dev(p))298 return -EINVAL;299 300 if (hwpoison_filter_flags(p))301 return -EINVAL;302 303 if (hwpoison_filter_task(p))304 return -EINVAL;305 306 return 0;307}308EXPORT_SYMBOL_GPL(hwpoison_filter);309#else310int hwpoison_filter(struct page *p)311{312 return 0;313}314#endif315 316/*317 * Kill all processes that have a poisoned page mapped and then isolate318 * the page.319 *320 * General strategy:321 * Find all processes having the page mapped and kill them.322 * But we keep a page reference around so that the page is not323 * actually freed yet.324 * Then stash the page away325 *326 * There's no convenient way to get back to mapped processes327 * from the VMAs. So do a brute-force search over all328 * running processes.329 *330 * Remember that machine checks are not common (or rather331 * if they are common you have other problems), so this shouldn't332 * be a performance issue.333 *334 * Also there are some races possible while we get from the335 * error detection to actually handle it.336 */337 338struct to_kill {339 struct list_head nd;340 struct task_struct *tsk;341 unsigned long addr;342 short size_shift;343};344 345/*346 * Send all the processes who have the page mapped a signal.347 * ``action optional'' if they are not immediately affected by the error348 * ``action required'' if error happened in current execution context349 */350static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)351{352 struct task_struct *t = tk->tsk;353 short addr_lsb = tk->size_shift;354 int ret = 0;355 356 pr_err("%#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",357 pfn, t->comm, task_pid_nr(t));358 359 if ((flags & MF_ACTION_REQUIRED) && (t == current))360 ret = force_sig_mceerr(BUS_MCEERR_AR,361 (void __user *)tk->addr, addr_lsb);362 else363 /*364 * Signal other processes sharing the page if they have365 * PF_MCE_EARLY set.366 * Don't use force here, it's convenient if the signal367 * can be temporarily blocked.368 */369 ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,370 addr_lsb, t);371 if (ret < 0)372 pr_info("Error sending signal to %s:%d: %d\n",373 t->comm, task_pid_nr(t), ret);374 return ret;375}376 377/*378 * Unknown page type encountered. Try to check whether it can turn PageLRU by379 * lru_add_drain_all.380 */381void shake_folio(struct folio *folio)382{383 if (folio_test_hugetlb(folio))384 return;385 /*386 * TODO: Could shrink slab caches here if a lightweight range-based387 * shrinker will be available.388 */389 if (folio_test_slab(folio))390 return;391 392 lru_add_drain_all();393}394EXPORT_SYMBOL_GPL(shake_folio);395 396static void shake_page(struct page *page)397{398 shake_folio(page_folio(page));399}400 401static unsigned long dev_pagemap_mapping_shift(struct vm_area_struct *vma,402 unsigned long address)403{404 unsigned long ret = 0;405 pgd_t *pgd;406 p4d_t *p4d;407 pud_t *pud;408 pmd_t *pmd;409 pte_t *pte;410 pte_t ptent;411 412 VM_BUG_ON_VMA(address == -EFAULT, vma);413 pgd = pgd_offset(vma->vm_mm, address);414 if (!pgd_present(*pgd))415 return 0;416 p4d = p4d_offset(pgd, address);417 if (!p4d_present(*p4d))418 return 0;419 pud = pud_offset(p4d, address);420 if (!pud_present(*pud))421 return 0;422 if (pud_devmap(*pud))423 return PUD_SHIFT;424 pmd = pmd_offset(pud, address);425 if (!pmd_present(*pmd))426 return 0;427 if (pmd_devmap(*pmd))428 return PMD_SHIFT;429 pte = pte_offset_map(pmd, address);430 if (!pte)431 return 0;432 ptent = ptep_get(pte);433 if (pte_present(ptent) && pte_devmap(ptent))434 ret = PAGE_SHIFT;435 pte_unmap(pte);436 return ret;437}438 439/*440 * Failure handling: if we can't find or can't kill a process there's441 * not much we can do. We just print a message and ignore otherwise.442 */443 444/*445 * Schedule a process for later kill.446 * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.447 */448static void __add_to_kill(struct task_struct *tsk, struct page *p,449 struct vm_area_struct *vma, struct list_head *to_kill,450 unsigned long addr)451{452 struct to_kill *tk;453 454 tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);455 if (!tk) {456 pr_err("Out of memory while machine check handling\n");457 return;458 }459 460 tk->addr = addr;461 if (is_zone_device_page(p))462 tk->size_shift = dev_pagemap_mapping_shift(vma, tk->addr);463 else464 tk->size_shift = page_shift(compound_head(p));465 466 /*467 * Send SIGKILL if "tk->addr == -EFAULT". Also, as468 * "tk->size_shift" is always non-zero for !is_zone_device_page(),469 * so "tk->size_shift == 0" effectively checks no mapping on470 * ZONE_DEVICE. Indeed, when a devdax page is mmapped N times471 * to a process' address space, it's possible not all N VMAs472 * contain mappings for the page, but at least one VMA does.473 * Only deliver SIGBUS with payload derived from the VMA that474 * has a mapping for the page.475 */476 if (tk->addr == -EFAULT) {477 pr_info("Unable to find user space address %lx in %s\n",478 page_to_pfn(p), tsk->comm);479 } else if (tk->size_shift == 0) {480 kfree(tk);481 return;482 }483 484 get_task_struct(tsk);485 tk->tsk = tsk;486 list_add_tail(&tk->nd, to_kill);487}488 489static void add_to_kill_anon_file(struct task_struct *tsk, struct page *p,490 struct vm_area_struct *vma, struct list_head *to_kill,491 unsigned long addr)492{493 if (addr == -EFAULT)494 return;495 __add_to_kill(tsk, p, vma, to_kill, addr);496}497 498#ifdef CONFIG_KSM499static bool task_in_to_kill_list(struct list_head *to_kill,500 struct task_struct *tsk)501{502 struct to_kill *tk, *next;503 504 list_for_each_entry_safe(tk, next, to_kill, nd) {505 if (tk->tsk == tsk)506 return true;507 }508 509 return false;510}511 512void add_to_kill_ksm(struct task_struct *tsk, struct page *p,513 struct vm_area_struct *vma, struct list_head *to_kill,514 unsigned long addr)515{516 if (!task_in_to_kill_list(to_kill, tsk))517 __add_to_kill(tsk, p, vma, to_kill, addr);518}519#endif520/*521 * Kill the processes that have been collected earlier.522 *523 * Only do anything when FORCEKILL is set, otherwise just free the524 * list (this is used for clean pages which do not need killing)525 */526static void kill_procs(struct list_head *to_kill, int forcekill,527 unsigned long pfn, int flags)528{529 struct to_kill *tk, *next;530 531 list_for_each_entry_safe(tk, next, to_kill, nd) {532 if (forcekill) {533 if (tk->addr == -EFAULT) {534 pr_err("%#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",535 pfn, tk->tsk->comm, task_pid_nr(tk->tsk));536 do_send_sig_info(SIGKILL, SEND_SIG_PRIV,537 tk->tsk, PIDTYPE_PID);538 }539 540 /*541 * In theory the process could have mapped542 * something else on the address in-between. We could543 * check for that, but we need to tell the544 * process anyways.545 */546 else if (kill_proc(tk, pfn, flags) < 0)547 pr_err("%#lx: Cannot send advisory machine check signal to %s:%d\n",548 pfn, tk->tsk->comm, task_pid_nr(tk->tsk));549 }550 list_del(&tk->nd);551 put_task_struct(tk->tsk);552 kfree(tk);553 }554}555 556/*557 * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)558 * on behalf of the thread group. Return task_struct of the (first found)559 * dedicated thread if found, and return NULL otherwise.560 *561 * We already hold rcu lock in the caller, so we don't have to call562 * rcu_read_lock/unlock() in this function.563 */564static struct task_struct *find_early_kill_thread(struct task_struct *tsk)565{566 struct task_struct *t;567 568 for_each_thread(tsk, t) {569 if (t->flags & PF_MCE_PROCESS) {570 if (t->flags & PF_MCE_EARLY)571 return t;572 } else {573 if (sysctl_memory_failure_early_kill)574 return t;575 }576 }577 return NULL;578}579 580/*581 * Determine whether a given process is "early kill" process which expects582 * to be signaled when some page under the process is hwpoisoned.583 * Return task_struct of the dedicated thread (main thread unless explicitly584 * specified) if the process is "early kill" and otherwise returns NULL.585 *586 * Note that the above is true for Action Optional case. For Action Required587 * case, it's only meaningful to the current thread which need to be signaled588 * with SIGBUS, this error is Action Optional for other non current589 * processes sharing the same error page,if the process is "early kill", the590 * task_struct of the dedicated thread will also be returned.591 */592struct task_struct *task_early_kill(struct task_struct *tsk, int force_early)593{594 if (!tsk->mm)595 return NULL;596 /*597 * Comparing ->mm here because current task might represent598 * a subthread, while tsk always points to the main thread.599 */600 if (force_early && tsk->mm == current->mm)601 return current;602 603 return find_early_kill_thread(tsk);604}605 606/*607 * Collect processes when the error hit an anonymous page.608 */609static void collect_procs_anon(struct folio *folio, struct page *page,610 struct list_head *to_kill, int force_early)611{612 struct task_struct *tsk;613 struct anon_vma *av;614 pgoff_t pgoff;615 616 av = folio_lock_anon_vma_read(folio, NULL);617 if (av == NULL) /* Not actually mapped anymore */618 return;619 620 pgoff = page_to_pgoff(page);621 rcu_read_lock();622 for_each_process(tsk) {623 struct vm_area_struct *vma;624 struct anon_vma_chain *vmac;625 struct task_struct *t = task_early_kill(tsk, force_early);626 unsigned long addr;627 628 if (!t)629 continue;630 anon_vma_interval_tree_foreach(vmac, &av->rb_root,631 pgoff, pgoff) {632 vma = vmac->vma;633 if (vma->vm_mm != t->mm)634 continue;635 addr = page_mapped_in_vma(page, vma);636 add_to_kill_anon_file(t, page, vma, to_kill, addr);637 }638 }639 rcu_read_unlock();640 anon_vma_unlock_read(av);641}642 643/*644 * Collect processes when the error hit a file mapped page.645 */646static void collect_procs_file(struct folio *folio, struct page *page,647 struct list_head *to_kill, int force_early)648{649 struct vm_area_struct *vma;650 struct task_struct *tsk;651 struct address_space *mapping = folio->mapping;652 pgoff_t pgoff;653 654 i_mmap_lock_read(mapping);655 rcu_read_lock();656 pgoff = page_to_pgoff(page);657 for_each_process(tsk) {658 struct task_struct *t = task_early_kill(tsk, force_early);659 unsigned long addr;660 661 if (!t)662 continue;663 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,664 pgoff) {665 /*666 * Send early kill signal to tasks where a vma covers667 * the page but the corrupted page is not necessarily668 * mapped in its pte.669 * Assume applications who requested early kill want670 * to be informed of all such data corruptions.671 */672 if (vma->vm_mm != t->mm)673 continue;674 addr = page_address_in_vma(page, vma);675 add_to_kill_anon_file(t, page, vma, to_kill, addr);676 }677 }678 rcu_read_unlock();679 i_mmap_unlock_read(mapping);680}681 682#ifdef CONFIG_FS_DAX683static void add_to_kill_fsdax(struct task_struct *tsk, struct page *p,684 struct vm_area_struct *vma,685 struct list_head *to_kill, pgoff_t pgoff)686{687 unsigned long addr = vma_address(vma, pgoff, 1);688 __add_to_kill(tsk, p, vma, to_kill, addr);689}690 691/*692 * Collect processes when the error hit a fsdax page.693 */694static void collect_procs_fsdax(struct page *page,695 struct address_space *mapping, pgoff_t pgoff,696 struct list_head *to_kill, bool pre_remove)697{698 struct vm_area_struct *vma;699 struct task_struct *tsk;700 701 i_mmap_lock_read(mapping);702 rcu_read_lock();703 for_each_process(tsk) {704 struct task_struct *t = tsk;705 706 /*707 * Search for all tasks while MF_MEM_PRE_REMOVE is set, because708 * the current may not be the one accessing the fsdax page.709 * Otherwise, search for the current task.710 */711 if (!pre_remove)712 t = task_early_kill(tsk, true);713 if (!t)714 continue;715 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {716 if (vma->vm_mm == t->mm)717 add_to_kill_fsdax(t, page, vma, to_kill, pgoff);718 }719 }720 rcu_read_unlock();721 i_mmap_unlock_read(mapping);722}723#endif /* CONFIG_FS_DAX */724 725/*726 * Collect the processes who have the corrupted page mapped to kill.727 */728static void collect_procs(struct folio *folio, struct page *page,729 struct list_head *tokill, int force_early)730{731 if (!folio->mapping)732 return;733 if (unlikely(folio_test_ksm(folio)))734 collect_procs_ksm(folio, page, tokill, force_early);735 else if (folio_test_anon(folio))736 collect_procs_anon(folio, page, tokill, force_early);737 else738 collect_procs_file(folio, page, tokill, force_early);739}740 741struct hwpoison_walk {742 struct to_kill tk;743 unsigned long pfn;744 int flags;745};746 747static void set_to_kill(struct to_kill *tk, unsigned long addr, short shift)748{749 tk->addr = addr;750 tk->size_shift = shift;751}752 753static int check_hwpoisoned_entry(pte_t pte, unsigned long addr, short shift,754 unsigned long poisoned_pfn, struct to_kill *tk)755{756 unsigned long pfn = 0;757 758 if (pte_present(pte)) {759 pfn = pte_pfn(pte);760 } else {761 swp_entry_t swp = pte_to_swp_entry(pte);762 763 if (is_hwpoison_entry(swp))764 pfn = swp_offset_pfn(swp);765 }766 767 if (!pfn || pfn != poisoned_pfn)768 return 0;769 770 set_to_kill(tk, addr, shift);771 return 1;772}773 774#ifdef CONFIG_TRANSPARENT_HUGEPAGE775static int check_hwpoisoned_pmd_entry(pmd_t *pmdp, unsigned long addr,776 struct hwpoison_walk *hwp)777{778 pmd_t pmd = *pmdp;779 unsigned long pfn;780 unsigned long hwpoison_vaddr;781 782 if (!pmd_present(pmd))783 return 0;784 pfn = pmd_pfn(pmd);785 if (pfn <= hwp->pfn && hwp->pfn < pfn + HPAGE_PMD_NR) {786 hwpoison_vaddr = addr + ((hwp->pfn - pfn) << PAGE_SHIFT);787 set_to_kill(&hwp->tk, hwpoison_vaddr, PAGE_SHIFT);788 return 1;789 }790 return 0;791}792#else793static int check_hwpoisoned_pmd_entry(pmd_t *pmdp, unsigned long addr,794 struct hwpoison_walk *hwp)795{796 return 0;797}798#endif799 800static int hwpoison_pte_range(pmd_t *pmdp, unsigned long addr,801 unsigned long end, struct mm_walk *walk)802{803 struct hwpoison_walk *hwp = walk->private;804 int ret = 0;805 pte_t *ptep, *mapped_pte;806 spinlock_t *ptl;807 808 ptl = pmd_trans_huge_lock(pmdp, walk->vma);809 if (ptl) {810 ret = check_hwpoisoned_pmd_entry(pmdp, addr, hwp);811 spin_unlock(ptl);812 goto out;813 }814 815 mapped_pte = ptep = pte_offset_map_lock(walk->vma->vm_mm, pmdp,816 addr, &ptl);817 if (!ptep)818 goto out;819 820 for (; addr != end; ptep++, addr += PAGE_SIZE) {821 ret = check_hwpoisoned_entry(ptep_get(ptep), addr, PAGE_SHIFT,822 hwp->pfn, &hwp->tk);823 if (ret == 1)824 break;825 }826 pte_unmap_unlock(mapped_pte, ptl);827out:828 cond_resched();829 return ret;830}831 832#ifdef CONFIG_HUGETLB_PAGE833static int hwpoison_hugetlb_range(pte_t *ptep, unsigned long hmask,834 unsigned long addr, unsigned long end,835 struct mm_walk *walk)836{837 struct hwpoison_walk *hwp = walk->private;838 pte_t pte = huge_ptep_get(walk->mm, addr, ptep);839 struct hstate *h = hstate_vma(walk->vma);840 841 return check_hwpoisoned_entry(pte, addr, huge_page_shift(h),842 hwp->pfn, &hwp->tk);843}844#else845#define hwpoison_hugetlb_range NULL846#endif847 848static const struct mm_walk_ops hwpoison_walk_ops = {849 .pmd_entry = hwpoison_pte_range,850 .hugetlb_entry = hwpoison_hugetlb_range,851 .walk_lock = PGWALK_RDLOCK,852};853 854/*855 * Sends SIGBUS to the current process with error info.856 *857 * This function is intended to handle "Action Required" MCEs on already858 * hardware poisoned pages. They could happen, for example, when859 * memory_failure() failed to unmap the error page at the first call, or860 * when multiple local machine checks happened on different CPUs.861 *862 * MCE handler currently has no easy access to the error virtual address,863 * so this function walks page table to find it. The returned virtual address864 * is proper in most cases, but it could be wrong when the application865 * process has multiple entries mapping the error page.866 */867static int kill_accessing_process(struct task_struct *p, unsigned long pfn,868 int flags)869{870 int ret;871 struct hwpoison_walk priv = {872 .pfn = pfn,873 };874 priv.tk.tsk = p;875 876 if (!p->mm)877 return -EFAULT;878 879 mmap_read_lock(p->mm);880 ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwpoison_walk_ops,881 (void *)&priv);882 if (ret == 1 && priv.tk.addr)883 kill_proc(&priv.tk, pfn, flags);884 else885 ret = 0;886 mmap_read_unlock(p->mm);887 return ret > 0 ? -EHWPOISON : -EFAULT;888}889 890/*891 * MF_IGNORED - The m-f() handler marks the page as PG_hwpoisoned'ed.892 * But it could not do more to isolate the page from being accessed again,893 * nor does it kill the process. This is extremely rare and one of the894 * potential causes is that the page state has been changed due to895 * underlying race condition. This is the most severe outcomes.896 *897 * MF_FAILED - The m-f() handler marks the page as PG_hwpoisoned'ed.898 * It should have killed the process, but it can't isolate the page,899 * due to conditions such as extra pin, unmap failure, etc. Accessing900 * the page again may trigger another MCE and the process will be killed901 * by the m-f() handler immediately.902 *903 * MF_DELAYED - The m-f() handler marks the page as PG_hwpoisoned'ed.904 * The page is unmapped, and is removed from the LRU or file mapping.905 * An attempt to access the page again will trigger page fault and the906 * PF handler will kill the process.907 *908 * MF_RECOVERED - The m-f() handler marks the page as PG_hwpoisoned'ed.909 * The page has been completely isolated, that is, unmapped, taken out of910 * the buddy system, or hole-punnched out of the file mapping.911 */912static const char *action_name[] = {913 [MF_IGNORED] = "Ignored",914 [MF_FAILED] = "Failed",915 [MF_DELAYED] = "Delayed",916 [MF_RECOVERED] = "Recovered",917};918 919static const char * const action_page_types[] = {920 [MF_MSG_KERNEL] = "reserved kernel page",921 [MF_MSG_KERNEL_HIGH_ORDER] = "high-order kernel page",922 [MF_MSG_HUGE] = "huge page",923 [MF_MSG_FREE_HUGE] = "free huge page",924 [MF_MSG_GET_HWPOISON] = "get hwpoison page",925 [MF_MSG_UNMAP_FAILED] = "unmapping failed page",926 [MF_MSG_DIRTY_SWAPCACHE] = "dirty swapcache page",927 [MF_MSG_CLEAN_SWAPCACHE] = "clean swapcache page",928 [MF_MSG_DIRTY_MLOCKED_LRU] = "dirty mlocked LRU page",929 [MF_MSG_CLEAN_MLOCKED_LRU] = "clean mlocked LRU page",930 [MF_MSG_DIRTY_UNEVICTABLE_LRU] = "dirty unevictable LRU page",931 [MF_MSG_CLEAN_UNEVICTABLE_LRU] = "clean unevictable LRU page",932 [MF_MSG_DIRTY_LRU] = "dirty LRU page",933 [MF_MSG_CLEAN_LRU] = "clean LRU page",934 [MF_MSG_TRUNCATED_LRU] = "already truncated LRU page",935 [MF_MSG_BUDDY] = "free buddy page",936 [MF_MSG_DAX] = "dax page",937 [MF_MSG_UNSPLIT_THP] = "unsplit thp",938 [MF_MSG_ALREADY_POISONED] = "already poisoned",939 [MF_MSG_UNKNOWN] = "unknown page",940};941 942/*943 * XXX: It is possible that a page is isolated from LRU cache,944 * and then kept in swap cache or failed to remove from page cache.945 * The page count will stop it from being freed by unpoison.946 * Stress tests should be aware of this memory leak problem.947 */948static int delete_from_lru_cache(struct folio *folio)949{950 if (folio_isolate_lru(folio)) {951 /*952 * Clear sensible page flags, so that the buddy system won't953 * complain when the folio is unpoison-and-freed.954 */955 folio_clear_active(folio);956 folio_clear_unevictable(folio);957 958 /*959 * Poisoned page might never drop its ref count to 0 so we have960 * to uncharge it manually from its memcg.961 */962 mem_cgroup_uncharge(folio);963 964 /*965 * drop the refcount elevated by folio_isolate_lru()966 */967 folio_put(folio);968 return 0;969 }970 return -EIO;971}972 973static int truncate_error_folio(struct folio *folio, unsigned long pfn,974 struct address_space *mapping)975{976 int ret = MF_FAILED;977 978 if (mapping->a_ops->error_remove_folio) {979 int err = mapping->a_ops->error_remove_folio(mapping, folio);980 981 if (err != 0)982 pr_info("%#lx: Failed to punch page: %d\n", pfn, err);983 else if (!filemap_release_folio(folio, GFP_NOIO))984 pr_info("%#lx: failed to release buffers\n", pfn);985 else986 ret = MF_RECOVERED;987 } else {988 /*989 * If the file system doesn't support it just invalidate990 * This fails on dirty or anything with private pages991 */992 if (mapping_evict_folio(mapping, folio))993 ret = MF_RECOVERED;994 else995 pr_info("%#lx: Failed to invalidate\n", pfn);996 }997 998 return ret;999}1000 1001struct page_state {1002 unsigned long mask;1003 unsigned long res;1004 enum mf_action_page_type type;1005 1006 /* Callback ->action() has to unlock the relevant page inside it. */1007 int (*action)(struct page_state *ps, struct page *p);1008};1009 1010/*1011 * Return true if page is still referenced by others, otherwise return1012 * false.1013 *1014 * The extra_pins is true when one extra refcount is expected.1015 */1016static bool has_extra_refcount(struct page_state *ps, struct page *p,1017 bool extra_pins)1018{1019 int count = page_count(p) - 1;1020 1021 if (extra_pins)1022 count -= folio_nr_pages(page_folio(p));1023 1024 if (count > 0) {1025 pr_err("%#lx: %s still referenced by %d users\n",1026 page_to_pfn(p), action_page_types[ps->type], count);1027 return true;1028 }1029 1030 return false;1031}1032 1033/*1034 * Error hit kernel page.1035 * Do nothing, try to be lucky and not touch this instead. For a few cases we1036 * could be more sophisticated.1037 */1038static int me_kernel(struct page_state *ps, struct page *p)1039{1040 unlock_page(p);1041 return MF_IGNORED;1042}1043 1044/*1045 * Page in unknown state. Do nothing.1046 * This is a catch-all in case we fail to make sense of the page state.1047 */1048static int me_unknown(struct page_state *ps, struct page *p)1049{1050 pr_err("%#lx: Unknown page state\n", page_to_pfn(p));1051 unlock_page(p);1052 return MF_IGNORED;1053}1054 1055/*1056 * Clean (or cleaned) page cache page.1057 */1058static int me_pagecache_clean(struct page_state *ps, struct page *p)1059{1060 struct folio *folio = page_folio(p);1061 int ret;1062 struct address_space *mapping;1063 bool extra_pins;1064 1065 delete_from_lru_cache(folio);1066 1067 /*1068 * For anonymous folios the only reference left1069 * should be the one m_f() holds.1070 */1071 if (folio_test_anon(folio)) {1072 ret = MF_RECOVERED;1073 goto out;1074 }1075 1076 /*1077 * Now truncate the page in the page cache. This is really1078 * more like a "temporary hole punch"1079 * Don't do this for block devices when someone else1080 * has a reference, because it could be file system metadata1081 * and that's not safe to truncate.1082 */1083 mapping = folio_mapping(folio);1084 if (!mapping) {1085 /* Folio has been torn down in the meantime */1086 ret = MF_FAILED;1087 goto out;1088 }1089 1090 /*1091 * The shmem page is kept in page cache instead of truncating1092 * so is expected to have an extra refcount after error-handling.1093 */1094 extra_pins = shmem_mapping(mapping);1095 1096 /*1097 * Truncation is a bit tricky. Enable it per file system for now.1098 *1099 * Open: to take i_rwsem or not for this? Right now we don't.1100 */1101 ret = truncate_error_folio(folio, page_to_pfn(p), mapping);1102 if (has_extra_refcount(ps, p, extra_pins))1103 ret = MF_FAILED;1104 1105out:1106 folio_unlock(folio);1107 1108 return ret;1109}1110 1111/*1112 * Dirty pagecache page1113 * Issues: when the error hit a hole page the error is not properly1114 * propagated.1115 */1116static int me_pagecache_dirty(struct page_state *ps, struct page *p)1117{1118 struct folio *folio = page_folio(p);1119 struct address_space *mapping = folio_mapping(folio);1120 1121 /* TBD: print more information about the file. */1122 if (mapping) {1123 /*1124 * IO error will be reported by write(), fsync(), etc.1125 * who check the mapping.1126 * This way the application knows that something went1127 * wrong with its dirty file data.1128 */1129 mapping_set_error(mapping, -EIO);1130 }1131 1132 return me_pagecache_clean(ps, p);1133}1134 1135/*1136 * Clean and dirty swap cache.1137 *1138 * Dirty swap cache page is tricky to handle. The page could live both in page1139 * table and swap cache(ie. page is freshly swapped in). So it could be1140 * referenced concurrently by 2 types of PTEs:1141 * normal PTEs and swap PTEs. We try to handle them consistently by calling1142 * try_to_unmap(!TTU_HWPOISON) to convert the normal PTEs to swap PTEs,1143 * and then1144 * - clear dirty bit to prevent IO1145 * - remove from LRU1146 * - but keep in the swap cache, so that when we return to it on1147 * a later page fault, we know the application is accessing1148 * corrupted data and shall be killed (we installed simple1149 * interception code in do_swap_page to catch it).1150 *1151 * Clean swap cache pages can be directly isolated. A later page fault will1152 * bring in the known good data from disk.1153 */1154static int me_swapcache_dirty(struct page_state *ps, struct page *p)1155{1156 struct folio *folio = page_folio(p);1157 int ret;1158 bool extra_pins = false;1159 1160 folio_clear_dirty(folio);1161 /* Trigger EIO in shmem: */1162 folio_clear_uptodate(folio);1163 1164 ret = delete_from_lru_cache(folio) ? MF_FAILED : MF_DELAYED;1165 folio_unlock(folio);1166 1167 if (ret == MF_DELAYED)1168 extra_pins = true;1169 1170 if (has_extra_refcount(ps, p, extra_pins))1171 ret = MF_FAILED;1172 1173 return ret;1174}1175 1176static int me_swapcache_clean(struct page_state *ps, struct page *p)1177{1178 struct folio *folio = page_folio(p);1179 int ret;1180 1181 delete_from_swap_cache(folio);1182 1183 ret = delete_from_lru_cache(folio) ? MF_FAILED : MF_RECOVERED;1184 folio_unlock(folio);1185 1186 if (has_extra_refcount(ps, p, false))1187 ret = MF_FAILED;1188 1189 return ret;1190}1191 1192/*1193 * Huge pages. Needs work.1194 * Issues:1195 * - Error on hugepage is contained in hugepage unit (not in raw page unit.)1196 * To narrow down kill region to one page, we need to break up pmd.1197 */1198static int me_huge_page(struct page_state *ps, struct page *p)1199{1200 struct folio *folio = page_folio(p);1201 int res;1202 struct address_space *mapping;1203 bool extra_pins = false;1204 1205 mapping = folio_mapping(folio);1206 if (mapping) {1207 res = truncate_error_folio(folio, page_to_pfn(p), mapping);1208 /* The page is kept in page cache. */1209 extra_pins = true;1210 folio_unlock(folio);1211 } else {1212 folio_unlock(folio);1213 /*1214 * migration entry prevents later access on error hugepage,1215 * so we can free and dissolve it into buddy to save healthy1216 * subpages.1217 */1218 folio_put(folio);1219 if (__page_handle_poison(p) > 0) {1220 page_ref_inc(p);1221 res = MF_RECOVERED;1222 } else {1223 res = MF_FAILED;1224 }1225 }1226 1227 if (has_extra_refcount(ps, p, extra_pins))1228 res = MF_FAILED;1229 1230 return res;1231}1232 1233/*1234 * Various page states we can handle.1235 *1236 * A page state is defined by its current page->flags bits.1237 * The table matches them in order and calls the right handler.1238 *1239 * This is quite tricky because we can access page at any time1240 * in its live cycle, so all accesses have to be extremely careful.1241 *1242 * This is not complete. More states could be added.1243 * For any missing state don't attempt recovery.1244 */1245 1246#define dirty (1UL << PG_dirty)1247#define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked))1248#define unevict (1UL << PG_unevictable)1249#define mlock (1UL << PG_mlocked)1250#define lru (1UL << PG_lru)1251#define head (1UL << PG_head)1252#define reserved (1UL << PG_reserved)1253 1254static struct page_state error_states[] = {1255 { reserved, reserved, MF_MSG_KERNEL, me_kernel },1256 /*1257 * free pages are specially detected outside this table:1258 * PG_buddy pages only make a small fraction of all free pages.1259 */1260 1261 { head, head, MF_MSG_HUGE, me_huge_page },1262 1263 { sc|dirty, sc|dirty, MF_MSG_DIRTY_SWAPCACHE, me_swapcache_dirty },1264 { sc|dirty, sc, MF_MSG_CLEAN_SWAPCACHE, me_swapcache_clean },1265 1266 { mlock|dirty, mlock|dirty, MF_MSG_DIRTY_MLOCKED_LRU, me_pagecache_dirty },1267 { mlock|dirty, mlock, MF_MSG_CLEAN_MLOCKED_LRU, me_pagecache_clean },1268 1269 { unevict|dirty, unevict|dirty, MF_MSG_DIRTY_UNEVICTABLE_LRU, me_pagecache_dirty },1270 { unevict|dirty, unevict, MF_MSG_CLEAN_UNEVICTABLE_LRU, me_pagecache_clean },1271 1272 { lru|dirty, lru|dirty, MF_MSG_DIRTY_LRU, me_pagecache_dirty },1273 { lru|dirty, lru, MF_MSG_CLEAN_LRU, me_pagecache_clean },1274 1275 /*1276 * Catchall entry: must be at end.1277 */1278 { 0, 0, MF_MSG_UNKNOWN, me_unknown },1279};1280 1281#undef dirty1282#undef sc1283#undef unevict1284#undef mlock1285#undef lru1286#undef head1287#undef reserved1288 1289static void update_per_node_mf_stats(unsigned long pfn,1290 enum mf_result result)1291{1292 int nid = MAX_NUMNODES;1293 struct memory_failure_stats *mf_stats = NULL;1294 1295 nid = pfn_to_nid(pfn);1296 if (unlikely(nid < 0 || nid >= MAX_NUMNODES)) {1297 WARN_ONCE(1, "Memory failure: pfn=%#lx, invalid nid=%d", pfn, nid);1298 return;1299 }1300 1301 mf_stats = &NODE_DATA(nid)->mf_stats;1302 switch (result) {1303 case MF_IGNORED:1304 ++mf_stats->ignored;1305 break;1306 case MF_FAILED:1307 ++mf_stats->failed;1308 break;1309 case MF_DELAYED:1310 ++mf_stats->delayed;1311 break;1312 case MF_RECOVERED:1313 ++mf_stats->recovered;1314 break;1315 default:1316 WARN_ONCE(1, "Memory failure: mf_result=%d is not properly handled", result);1317 break;1318 }1319 ++mf_stats->total;1320}1321 1322/*1323 * "Dirty/Clean" indication is not 100% accurate due to the possibility of1324 * setting PG_dirty outside page lock. See also comment above set_page_dirty().1325 */1326static int action_result(unsigned long pfn, enum mf_action_page_type type,1327 enum mf_result result)1328{1329 trace_memory_failure_event(pfn, type, result);1330 1331 num_poisoned_pages_inc(pfn);1332 1333 update_per_node_mf_stats(pfn, result);1334 1335 pr_err("%#lx: recovery action for %s: %s\n",1336 pfn, action_page_types[type], action_name[result]);1337 1338 return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;1339}1340 1341static int page_action(struct page_state *ps, struct page *p,1342 unsigned long pfn)1343{1344 int result;1345 1346 /* page p should be unlocked after returning from ps->action(). */1347 result = ps->action(ps, p);1348 1349 /* Could do more checks here if page looks ok */1350 /*1351 * Could adjust zone counters here to correct for the missing page.1352 */1353 1354 return action_result(pfn, ps->type, result);1355}1356 1357static inline bool PageHWPoisonTakenOff(struct page *page)1358{1359 return PageHWPoison(page) && page_private(page) == MAGIC_HWPOISON;1360}1361 1362void SetPageHWPoisonTakenOff(struct page *page)1363{1364 set_page_private(page, MAGIC_HWPOISON);1365}1366 1367void ClearPageHWPoisonTakenOff(struct page *page)1368{1369 if (PageHWPoison(page))1370 set_page_private(page, 0);1371}1372 1373/*1374 * Return true if a page type of a given page is supported by hwpoison1375 * mechanism (while handling could fail), otherwise false. This function1376 * does not return true for hugetlb or device memory pages, so it's assumed1377 * to be called only in the context where we never have such pages.1378 */1379static inline bool HWPoisonHandlable(struct page *page, unsigned long flags)1380{1381 if (PageSlab(page))1382 return false;1383 1384 /* Soft offline could migrate non-LRU movable pages */1385 if ((flags & MF_SOFT_OFFLINE) && __PageMovable(page))1386 return true;1387 1388 return PageLRU(page) || is_free_buddy_page(page);1389}1390 1391static int __get_hwpoison_page(struct page *page, unsigned long flags)1392{1393 struct folio *folio = page_folio(page);1394 int ret = 0;1395 bool hugetlb = false;1396 1397 ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, false);1398 if (hugetlb) {1399 /* Make sure hugetlb demotion did not happen from under us. */1400 if (folio == page_folio(page))1401 return ret;1402 if (ret > 0) {1403 folio_put(folio);1404 folio = page_folio(page);1405 }1406 }1407 1408 /*1409 * This check prevents from calling folio_try_get() for any1410 * unsupported type of folio in order to reduce the risk of unexpected1411 * races caused by taking a folio refcount.1412 */1413 if (!HWPoisonHandlable(&folio->page, flags))1414 return -EBUSY;1415 1416 if (folio_try_get(folio)) {1417 if (folio == page_folio(page))1418 return 1;1419 1420 pr_info("%#lx cannot catch tail\n", page_to_pfn(page));1421 folio_put(folio);1422 }1423 1424 return 0;1425}1426 1427#define GET_PAGE_MAX_RETRY_NUM 31428 1429static int get_any_page(struct page *p, unsigned long flags)1430{1431 int ret = 0, pass = 0;1432 bool count_increased = false;1433 1434 if (flags & MF_COUNT_INCREASED)1435 count_increased = true;1436 1437try_again:1438 if (!count_increased) {1439 ret = __get_hwpoison_page(p, flags);1440 if (!ret) {1441 if (page_count(p)) {1442 /* We raced with an allocation, retry. */1443 if (pass++ < GET_PAGE_MAX_RETRY_NUM)1444 goto try_again;1445 ret = -EBUSY;1446 } else if (!PageHuge(p) && !is_free_buddy_page(p)) {1447 /* We raced with put_page, retry. */1448 if (pass++ < GET_PAGE_MAX_RETRY_NUM)1449 goto try_again;1450 ret = -EIO;1451 }1452 goto out;1453 } else if (ret == -EBUSY) {1454 /*1455 * We raced with (possibly temporary) unhandlable1456 * page, retry.1457 */1458 if (pass++ < 3) {1459 shake_page(p);1460 goto try_again;1461 }1462 ret = -EIO;1463 goto out;1464 }1465 }1466 1467 if (PageHuge(p) || HWPoisonHandlable(p, flags)) {1468 ret = 1;1469 } else {1470 /*1471 * A page we cannot handle. Check whether we can turn1472 * it into something we can handle.1473 */1474 if (pass++ < GET_PAGE_MAX_RETRY_NUM) {1475 put_page(p);1476 shake_page(p);1477 count_increased = false;1478 goto try_again;1479 }1480 put_page(p);1481 ret = -EIO;1482 }1483out:1484 if (ret == -EIO)1485 pr_err("%#lx: unhandlable page.\n", page_to_pfn(p));1486 1487 return ret;1488}1489 1490static int __get_unpoison_page(struct page *page)1491{1492 struct folio *folio = page_folio(page);1493 int ret = 0;1494 bool hugetlb = false;1495 1496 ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, true);1497 if (hugetlb) {1498 /* Make sure hugetlb demotion did not happen from under us. */1499 if (folio == page_folio(page))1500 return ret;1501 if (ret > 0)1502 folio_put(folio);1503 }1504 1505 /*1506 * PageHWPoisonTakenOff pages are not only marked as PG_hwpoison,1507 * but also isolated from buddy freelist, so need to identify the1508 * state and have to cancel both operations to unpoison.1509 */1510 if (PageHWPoisonTakenOff(page))1511 return -EHWPOISON;1512 1513 return get_page_unless_zero(page) ? 1 : 0;1514}1515 1516/**1517 * get_hwpoison_page() - Get refcount for memory error handling1518 * @p: Raw error page (hit by memory error)1519 * @flags: Flags controlling behavior of error handling1520 *1521 * get_hwpoison_page() takes a page refcount of an error page to handle memory1522 * error on it, after checking that the error page is in a well-defined state1523 * (defined as a page-type we can successfully handle the memory error on it,1524 * such as LRU page and hugetlb page).1525 *1526 * Memory error handling could be triggered at any time on any type of page,1527 * so it's prone to race with typical memory management lifecycle (like1528 * allocation and free). So to avoid such races, get_hwpoison_page() takes1529 * extra care for the error page's state (as done in __get_hwpoison_page()),1530 * and has some retry logic in get_any_page().1531 *1532 * When called from unpoison_memory(), the caller should already ensure that1533 * the given page has PG_hwpoison. So it's never reused for other page1534 * allocations, and __get_unpoison_page() never races with them.1535 *1536 * Return: 0 on failure or free buddy (hugetlb) page,1537 * 1 on success for in-use pages in a well-defined state,1538 * -EIO for pages on which we can not handle memory errors,1539 * -EBUSY when get_hwpoison_page() has raced with page lifecycle1540 * operations like allocation and free,1541 * -EHWPOISON when the page is hwpoisoned and taken off from buddy.1542 */1543static int get_hwpoison_page(struct page *p, unsigned long flags)1544{1545 int ret;1546 1547 zone_pcp_disable(page_zone(p));1548 if (flags & MF_UNPOISON)1549 ret = __get_unpoison_page(p);1550 else1551 ret = get_any_page(p, flags);1552 zone_pcp_enable(page_zone(p));1553 1554 return ret;1555}1556 1557void unmap_poisoned_folio(struct folio *folio, enum ttu_flags ttu)1558{1559 if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) {1560 struct address_space *mapping;1561 1562 /*1563 * For hugetlb folios in shared mappings, try_to_unmap1564 * could potentially call huge_pmd_unshare. Because of1565 * this, take semaphore in write mode here and set1566 * TTU_RMAP_LOCKED to indicate we have taken the lock1567 * at this higher level.1568 */1569 mapping = hugetlb_folio_mapping_lock_write(folio);1570 if (!mapping) {1571 pr_info("%#lx: could not lock mapping for mapped hugetlb folio\n",1572 folio_pfn(folio));1573 return;1574 }1575 1576 try_to_unmap(folio, ttu|TTU_RMAP_LOCKED);1577 i_mmap_unlock_write(mapping);1578 } else {1579 try_to_unmap(folio, ttu);1580 }1581}1582 1583/*1584 * Do all that is necessary to remove user space mappings. Unmap1585 * the pages and send SIGBUS to the processes if the data was dirty.1586 */1587static bool hwpoison_user_mappings(struct folio *folio, struct page *p,1588 unsigned long pfn, int flags)1589{1590 enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC | TTU_HWPOISON;1591 struct address_space *mapping;1592 LIST_HEAD(tokill);1593 bool unmap_success;1594 int forcekill;1595 bool mlocked = folio_test_mlocked(folio);1596 1597 /*1598 * Here we are interested only in user-mapped pages, so skip any1599 * other types of pages.1600 */1601 if (folio_test_reserved(folio) || folio_test_slab(folio) ||1602 folio_test_pgtable(folio) || folio_test_offline(folio))1603 return true;1604 if (!(folio_test_lru(folio) || folio_test_hugetlb(folio)))1605 return true;1606 1607 /*1608 * This check implies we don't kill processes if their pages1609 * are in the swap cache early. Those are always late kills.1610 */1611 if (!folio_mapped(folio))1612 return true;1613 1614 if (folio_test_swapcache(folio)) {1615 pr_err("%#lx: keeping poisoned page in swap cache\n", pfn);1616 ttu &= ~TTU_HWPOISON;1617 }1618 1619 /*1620 * Propagate the dirty bit from PTEs to struct page first, because we1621 * need this to decide if we should kill or just drop the page.1622 * XXX: the dirty test could be racy: set_page_dirty() may not always1623 * be called inside page lock (it's recommended but not enforced).1624 */1625 mapping = folio_mapping(folio);1626 if (!(flags & MF_MUST_KILL) && !folio_test_dirty(folio) && mapping &&1627 mapping_can_writeback(mapping)) {1628 if (folio_mkclean(folio)) {1629 folio_set_dirty(folio);1630 } else {1631 ttu &= ~TTU_HWPOISON;1632 pr_info("%#lx: corrupted page was clean: dropped without side effects\n",1633 pfn);1634 }1635 }1636 1637 /*1638 * First collect all the processes that have the page1639 * mapped in dirty form. This has to be done before try_to_unmap,1640 * because ttu takes the rmap data structures down.1641 */1642 collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);1643 1644 unmap_poisoned_folio(folio, ttu);1645 1646 unmap_success = !folio_mapped(folio);1647 if (!unmap_success)1648 pr_err("%#lx: failed to unmap page (folio mapcount=%d)\n",1649 pfn, folio_mapcount(folio));1650 1651 /*1652 * try_to_unmap() might put mlocked page in lru cache, so call1653 * shake_page() again to ensure that it's flushed.1654 */1655 if (mlocked)1656 shake_folio(folio);1657 1658 /*1659 * Now that the dirty bit has been propagated to the1660 * struct page and all unmaps done we can decide if1661 * killing is needed or not. Only kill when the page1662 * was dirty or the process is not restartable,1663 * otherwise the tokill list is merely1664 * freed. When there was a problem unmapping earlier1665 * use a more force-full uncatchable kill to prevent1666 * any accesses to the poisoned memory.1667 */1668 forcekill = folio_test_dirty(folio) || (flags & MF_MUST_KILL) ||1669 !unmap_success;1670 kill_procs(&tokill, forcekill, pfn, flags);1671 1672 return unmap_success;1673}1674 1675static int identify_page_state(unsigned long pfn, struct page *p,1676 unsigned long page_flags)1677{1678 struct page_state *ps;1679 1680 /*1681 * The first check uses the current page flags which may not have any1682 * relevant information. The second check with the saved page flags is1683 * carried out only if the first check can't determine the page status.1684 */1685 for (ps = error_states;; ps++)1686 if ((p->flags & ps->mask) == ps->res)1687 break;1688 1689 page_flags |= (p->flags & (1UL << PG_dirty));1690 1691 if (!ps->mask)1692 for (ps = error_states;; ps++)1693 if ((page_flags & ps->mask) == ps->res)1694 break;1695 return page_action(ps, p, pfn);1696}1697 1698/*1699 * When 'release' is 'false', it means that if thp split has failed,1700 * there is still more to do, hence the page refcount we took earlier1701 * is still needed.1702 */1703static int try_to_split_thp_page(struct page *page, bool release)1704{1705 int ret;1706 1707 lock_page(page);1708 ret = split_huge_page(page);1709 unlock_page(page);1710 1711 if (ret && release)1712 put_page(page);1713 1714 return ret;1715}1716 1717static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,1718 struct address_space *mapping, pgoff_t index, int flags)1719{1720 struct to_kill *tk;1721 unsigned long size = 0;1722 1723 list_for_each_entry(tk, to_kill, nd)1724 if (tk->size_shift)1725 size = max(size, 1UL << tk->size_shift);1726 1727 if (size) {1728 /*1729 * Unmap the largest mapping to avoid breaking up device-dax1730 * mappings which are constant size. The actual size of the1731 * mapping being torn down is communicated in siginfo, see1732 * kill_proc()1733 */1734 loff_t start = ((loff_t)index << PAGE_SHIFT) & ~(size - 1);1735 1736 unmap_mapping_range(mapping, start, size, 0);1737 }1738 1739 kill_procs(to_kill, flags & MF_MUST_KILL, pfn, flags);1740}1741 1742/*1743 * Only dev_pagemap pages get here, such as fsdax when the filesystem1744 * either do not claim or fails to claim a hwpoison event, or devdax.1745 * The fsdax pages are initialized per base page, and the devdax pages1746 * could be initialized either as base pages, or as compound pages with1747 * vmemmap optimization enabled. Devdax is simplistic in its dealing with1748 * hwpoison, such that, if a subpage of a compound page is poisoned,1749 * simply mark the compound head page is by far sufficient.1750 */1751static int mf_generic_kill_procs(unsigned long long pfn, int flags,1752 struct dev_pagemap *pgmap)1753{1754 struct folio *folio = pfn_folio(pfn);1755 LIST_HEAD(to_kill);1756 dax_entry_t cookie;1757 int rc = 0;1758 1759 /*1760 * Prevent the inode from being freed while we are interrogating1761 * the address_space, typically this would be handled by1762 * lock_page(), but dax pages do not use the page lock. This1763 * also prevents changes to the mapping of this pfn until1764 * poison signaling is complete.1765 */1766 cookie = dax_lock_folio(folio);1767 if (!cookie)1768 return -EBUSY;1769 1770 if (hwpoison_filter(&folio->page)) {1771 rc = -EOPNOTSUPP;1772 goto unlock;1773 }1774 1775 switch (pgmap->type) {1776 case MEMORY_DEVICE_PRIVATE:1777 case MEMORY_DEVICE_COHERENT:1778 /*1779 * TODO: Handle device pages which may need coordination1780 * with device-side memory.1781 */1782 rc = -ENXIO;1783 goto unlock;1784 default:1785 break;1786 }1787 1788 /*1789 * Use this flag as an indication that the dax page has been1790 * remapped UC to prevent speculative consumption of poison.1791 */1792 SetPageHWPoison(&folio->page);1793 1794 /*1795 * Unlike System-RAM there is no possibility to swap in a1796 * different physical page at a given virtual address, so all1797 * userspace consumption of ZONE_DEVICE memory necessitates1798 * SIGBUS (i.e. MF_MUST_KILL)1799 */1800 flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;1801 collect_procs(folio, &folio->page, &to_kill, true);1802 1803 unmap_and_kill(&to_kill, pfn, folio->mapping, folio->index, flags);1804unlock:1805 dax_unlock_folio(folio, cookie);1806 return rc;1807}1808 1809#ifdef CONFIG_FS_DAX1810/**1811 * mf_dax_kill_procs - Collect and kill processes who are using this file range1812 * @mapping: address_space of the file in use1813 * @index: start pgoff of the range within the file1814 * @count: length of the range, in unit of PAGE_SIZE1815 * @mf_flags: memory failure flags1816 */1817int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,1818 unsigned long count, int mf_flags)1819{1820 LIST_HEAD(to_kill);1821 dax_entry_t cookie;1822 struct page *page;1823 size_t end = index + count;1824 bool pre_remove = mf_flags & MF_MEM_PRE_REMOVE;1825 1826 mf_flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;1827 1828 for (; index < end; index++) {1829 page = NULL;1830 cookie = dax_lock_mapping_entry(mapping, index, &page);1831 if (!cookie)1832 return -EBUSY;1833 if (!page)1834 goto unlock;1835 1836 if (!pre_remove)1837 SetPageHWPoison(page);1838 1839 /*1840 * The pre_remove case is revoking access, the memory is still1841 * good and could theoretically be put back into service.1842 */1843 collect_procs_fsdax(page, mapping, index, &to_kill, pre_remove);1844 unmap_and_kill(&to_kill, page_to_pfn(page), mapping,1845 index, mf_flags);1846unlock:1847 dax_unlock_mapping_entry(mapping, index, cookie);1848 }1849 return 0;1850}1851EXPORT_SYMBOL_GPL(mf_dax_kill_procs);1852#endif /* CONFIG_FS_DAX */1853 1854#ifdef CONFIG_HUGETLB_PAGE1855 1856/*1857 * Struct raw_hwp_page represents information about "raw error page",1858 * constructing singly linked list from ->_hugetlb_hwpoison field of folio.1859 */1860struct raw_hwp_page {1861 struct llist_node node;1862 struct page *page;1863};1864 1865static inline struct llist_head *raw_hwp_list_head(struct folio *folio)1866{1867 return (struct llist_head *)&folio->_hugetlb_hwpoison;1868}1869 1870bool is_raw_hwpoison_page_in_hugepage(struct page *page)1871{1872 struct llist_head *raw_hwp_head;1873 struct raw_hwp_page *p;1874 struct folio *folio = page_folio(page);1875 bool ret = false;1876 1877 if (!folio_test_hwpoison(folio))1878 return false;1879 1880 if (!folio_test_hugetlb(folio))1881 return PageHWPoison(page);1882 1883 /*1884 * When RawHwpUnreliable is set, kernel lost track of which subpages1885 * are HWPOISON. So return as if ALL subpages are HWPOISONed.1886 */1887 if (folio_test_hugetlb_raw_hwp_unreliable(folio))1888 return true;1889 1890 mutex_lock(&mf_mutex);1891 1892 raw_hwp_head = raw_hwp_list_head(folio);1893 llist_for_each_entry(p, raw_hwp_head->first, node) {1894 if (page == p->page) {1895 ret = true;1896 break;1897 }1898 }1899 1900 mutex_unlock(&mf_mutex);1901 1902 return ret;1903}1904 1905static unsigned long __folio_free_raw_hwp(struct folio *folio, bool move_flag)1906{1907 struct llist_node *head;1908 struct raw_hwp_page *p, *next;1909 unsigned long count = 0;1910 1911 head = llist_del_all(raw_hwp_list_head(folio));1912 llist_for_each_entry_safe(p, next, head, node) {1913 if (move_flag)1914 SetPageHWPoison(p->page);1915 else1916 num_poisoned_pages_sub(page_to_pfn(p->page), 1);1917 kfree(p);1918 count++;1919 }1920 return count;1921}1922 1923static int folio_set_hugetlb_hwpoison(struct folio *folio, struct page *page)1924{1925 struct llist_head *head;1926 struct raw_hwp_page *raw_hwp;1927 struct raw_hwp_page *p;1928 int ret = folio_test_set_hwpoison(folio) ? -EHWPOISON : 0;1929 1930 /*1931 * Once the hwpoison hugepage has lost reliable raw error info,1932 * there is little meaning to keep additional error info precisely,1933 * so skip to add additional raw error info.1934 */1935 if (folio_test_hugetlb_raw_hwp_unreliable(folio))1936 return -EHWPOISON;1937 head = raw_hwp_list_head(folio);1938 llist_for_each_entry(p, head->first, node) {1939 if (p->page == page)1940 return -EHWPOISON;1941 }1942 1943 raw_hwp = kmalloc(sizeof(struct raw_hwp_page), GFP_ATOMIC);1944 if (raw_hwp) {1945 raw_hwp->page = page;1946 llist_add(&raw_hwp->node, head);1947 /* the first error event will be counted in action_result(). */1948 if (ret)1949 num_poisoned_pages_inc(page_to_pfn(page));1950 } else {1951 /*1952 * Failed to save raw error info. We no longer trace all1953 * hwpoisoned subpages, and we need refuse to free/dissolve1954 * this hwpoisoned hugepage.1955 */1956 folio_set_hugetlb_raw_hwp_unreliable(folio);1957 /*1958 * Once hugetlb_raw_hwp_unreliable is set, raw_hwp_page is not1959 * used any more, so free it.1960 */1961 __folio_free_raw_hwp(folio, false);1962 }1963 return ret;1964}1965 1966static unsigned long folio_free_raw_hwp(struct folio *folio, bool move_flag)1967{1968 /*1969 * hugetlb_vmemmap_optimized hugepages can't be freed because struct1970 * pages for tail pages are required but they don't exist.1971 */1972 if (move_flag && folio_test_hugetlb_vmemmap_optimized(folio))1973 return 0;1974 1975 /*1976 * hugetlb_raw_hwp_unreliable hugepages shouldn't be unpoisoned by1977 * definition.1978 */1979 if (folio_test_hugetlb_raw_hwp_unreliable(folio))1980 return 0;1981 1982 return __folio_free_raw_hwp(folio, move_flag);1983}1984 1985void folio_clear_hugetlb_hwpoison(struct folio *folio)1986{1987 if (folio_test_hugetlb_raw_hwp_unreliable(folio))1988 return;1989 if (folio_test_hugetlb_vmemmap_optimized(folio))1990 return;1991 folio_clear_hwpoison(folio);1992 folio_free_raw_hwp(folio, true);1993}1994 1995/*1996 * Called from hugetlb code with hugetlb_lock held.1997 *1998 * Return values:1999 * 0 - free hugepage2000 * 1 - in-use hugepage2001 * 2 - not a hugepage2002 * -EBUSY - the hugepage is busy (try to retry)2003 * -EHWPOISON - the hugepage is already hwpoisoned2004 */2005int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,2006 bool *migratable_cleared)2007{2008 struct page *page = pfn_to_page(pfn);2009 struct folio *folio = page_folio(page);2010 int ret = 2; /* fallback to normal page handling */2011 bool count_increased = false;2012 2013 if (!folio_test_hugetlb(folio))2014 goto out;2015 2016 if (flags & MF_COUNT_INCREASED) {2017 ret = 1;2018 count_increased = true;2019 } else if (folio_test_hugetlb_freed(folio)) {2020 ret = 0;2021 } else if (folio_test_hugetlb_migratable(folio)) {2022 ret = folio_try_get(folio);2023 if (ret)2024 count_increased = true;2025 } else {2026 ret = -EBUSY;2027 if (!(flags & MF_NO_RETRY))2028 goto out;2029 }2030 2031 if (folio_set_hugetlb_hwpoison(folio, page)) {2032 ret = -EHWPOISON;2033 goto out;2034 }2035 2036 /*2037 * Clearing hugetlb_migratable for hwpoisoned hugepages to prevent them2038 * from being migrated by memory hotremove.2039 */2040 if (count_increased && folio_test_hugetlb_migratable(folio)) {2041 folio_clear_hugetlb_migratable(folio);2042 *migratable_cleared = true;2043 }2044 2045 return ret;2046out:2047 if (count_increased)2048 folio_put(folio);2049 return ret;2050}2051 2052/*2053 * Taking refcount of hugetlb pages needs extra care about race conditions2054 * with basic operations like hugepage allocation/free/demotion.2055 * So some of prechecks for hwpoison (pinning, and testing/setting2056 * PageHWPoison) should be done in single hugetlb_lock range.2057 */2058static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb)2059{2060 int res;2061 struct page *p = pfn_to_page(pfn);2062 struct folio *folio;2063 unsigned long page_flags;2064 bool migratable_cleared = false;2065 2066 *hugetlb = 1;2067retry:2068 res = get_huge_page_for_hwpoison(pfn, flags, &migratable_cleared);2069 if (res == 2) { /* fallback to normal page handling */2070 *hugetlb = 0;2071 return 0;2072 } else if (res == -EHWPOISON) {2073 pr_err("%#lx: already hardware poisoned\n", pfn);2074 if (flags & MF_ACTION_REQUIRED) {2075 folio = page_folio(p);2076 res = kill_accessing_process(current, folio_pfn(folio), flags);2077 action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED);2078 }2079 return res;2080 } else if (res == -EBUSY) {2081 if (!(flags & MF_NO_RETRY)) {2082 flags |= MF_NO_RETRY;2083 goto retry;2084 }2085 return action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED);2086 }2087 2088 folio = page_folio(p);2089 folio_lock(folio);2090 2091 if (hwpoison_filter(p)) {2092 folio_clear_hugetlb_hwpoison(folio);2093 if (migratable_cleared)2094 folio_set_hugetlb_migratable(folio);2095 folio_unlock(folio);2096 if (res == 1)2097 folio_put(folio);2098 return -EOPNOTSUPP;2099 }2100 2101 /*2102 * Handling free hugepage. The possible race with hugepage allocation2103 * or demotion can be prevented by PageHWPoison flag.2104 */2105 if (res == 0) {2106 folio_unlock(folio);2107 if (__page_handle_poison(p) > 0) {2108 page_ref_inc(p);2109 res = MF_RECOVERED;2110 } else {2111 res = MF_FAILED;2112 }2113 return action_result(pfn, MF_MSG_FREE_HUGE, res);2114 }2115 2116 page_flags = folio->flags;2117 2118 if (!hwpoison_user_mappings(folio, p, pfn, flags)) {2119 folio_unlock(folio);2120 return action_result(pfn, MF_MSG_UNMAP_FAILED, MF_FAILED);2121 }2122 2123 return identify_page_state(pfn, p, page_flags);2124}2125 2126#else2127static inline int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb)2128{2129 return 0;2130}2131 2132static inline unsigned long folio_free_raw_hwp(struct folio *folio, bool flag)2133{2134 return 0;2135}2136#endif /* CONFIG_HUGETLB_PAGE */2137 2138/* Drop the extra refcount in case we come from madvise() */2139static void put_ref_page(unsigned long pfn, int flags)2140{2141 if (!(flags & MF_COUNT_INCREASED))2142 return;2143 2144 put_page(pfn_to_page(pfn));2145}2146 2147static int memory_failure_dev_pagemap(unsigned long pfn, int flags,2148 struct dev_pagemap *pgmap)2149{2150 int rc = -ENXIO;2151 2152 /* device metadata space is not recoverable */2153 if (!pgmap_pfn_valid(pgmap, pfn))2154 goto out;2155 2156 /*2157 * Call driver's implementation to handle the memory failure, otherwise2158 * fall back to generic handler.2159 */2160 if (pgmap_has_memory_failure(pgmap)) {2161 rc = pgmap->ops->memory_failure(pgmap, pfn, 1, flags);2162 /*2163 * Fall back to generic handler too if operation is not2164 * supported inside the driver/device/filesystem.2165 */2166 if (rc != -EOPNOTSUPP)2167 goto out;2168 }2169 2170 rc = mf_generic_kill_procs(pfn, flags, pgmap);2171out:2172 /* drop pgmap ref acquired in caller */2173 put_dev_pagemap(pgmap);2174 if (rc != -EOPNOTSUPP)2175 action_result(pfn, MF_MSG_DAX, rc ? MF_FAILED : MF_RECOVERED);2176 return rc;2177}2178 2179/*2180 * The calling condition is as such: thp split failed, page might have2181 * been RDMA pinned, not much can be done for recovery.2182 * But a SIGBUS should be delivered with vaddr provided so that the user2183 * application has a chance to recover. Also, application processes'2184 * election for MCE early killed will be honored.2185 */2186static void kill_procs_now(struct page *p, unsigned long pfn, int flags,2187 struct folio *folio)2188{2189 LIST_HEAD(tokill);2190 2191 collect_procs(folio, p, &tokill, flags & MF_ACTION_REQUIRED);2192 kill_procs(&tokill, true, pfn, flags);2193}2194 2195/**2196 * memory_failure - Handle memory failure of a page.2197 * @pfn: Page Number of the corrupted page2198 * @flags: fine tune action taken2199 *2200 * This function is called by the low level machine check code2201 * of an architecture when it detects hardware memory corruption2202 * of a page. It tries its best to recover, which includes2203 * dropping pages, killing processes etc.2204 *2205 * The function is primarily of use for corruptions that2206 * happen outside the current execution context (e.g. when2207 * detected by a background scrubber)2208 *2209 * Must run in process context (e.g. a work queue) with interrupts2210 * enabled and no spinlocks held.2211 *2212 * Return: 0 for successfully handled the memory error,2213 * -EOPNOTSUPP for hwpoison_filter() filtered the error event,2214 * < 0(except -EOPNOTSUPP) on failure.2215 */2216int memory_failure(unsigned long pfn, int flags)2217{2218 struct page *p;2219 struct folio *folio;2220 struct dev_pagemap *pgmap;2221 int res = 0;2222 unsigned long page_flags;2223 bool retry = true;2224 int hugetlb = 0;2225 2226 if (!sysctl_memory_failure_recovery)2227 panic("Memory failure on page %lx", pfn);2228 2229 mutex_lock(&mf_mutex);2230 2231 if (!(flags & MF_SW_SIMULATED))2232 hw_memory_failure = true;2233 2234 p = pfn_to_online_page(pfn);2235 if (!p) {2236 res = arch_memory_failure(pfn, flags);2237 if (res == 0)2238 goto unlock_mutex;2239 2240 if (pfn_valid(pfn)) {2241 pgmap = get_dev_pagemap(pfn, NULL);2242 put_ref_page(pfn, flags);2243 if (pgmap) {2244 res = memory_failure_dev_pagemap(pfn, flags,2245 pgmap);2246 goto unlock_mutex;2247 }2248 }2249 pr_err("%#lx: memory outside kernel control\n", pfn);2250 res = -ENXIO;2251 goto unlock_mutex;2252 }2253 2254try_again:2255 res = try_memory_failure_hugetlb(pfn, flags, &hugetlb);2256 if (hugetlb)2257 goto unlock_mutex;2258 2259 if (TestSetPageHWPoison(p)) {2260 pr_err("%#lx: already hardware poisoned\n", pfn);2261 res = -EHWPOISON;2262 if (flags & MF_ACTION_REQUIRED)2263 res = kill_accessing_process(current, pfn, flags);2264 if (flags & MF_COUNT_INCREASED)2265 put_page(p);2266 action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED);2267 goto unlock_mutex;2268 }2269 2270 /*2271 * We need/can do nothing about count=0 pages.2272 * 1) it's a free page, and therefore in safe hand:2273 * check_new_page() will be the gate keeper.2274 * 2) it's part of a non-compound high order page.2275 * Implies some kernel user: cannot stop them from2276 * R/W the page; let's pray that the page has been2277 * used and will be freed some time later.2278 * In fact it's dangerous to directly bump up page count from 0,2279 * that may make page_ref_freeze()/page_ref_unfreeze() mismatch.2280 */2281 if (!(flags & MF_COUNT_INCREASED)) {2282 res = get_hwpoison_page(p, flags);2283 if (!res) {2284 if (is_free_buddy_page(p)) {2285 if (take_page_off_buddy(p)) {2286 page_ref_inc(p);2287 res = MF_RECOVERED;2288 } else {2289 /* We lost the race, try again */2290 if (retry) {2291 ClearPageHWPoison(p);2292 retry = false;2293 goto try_again;2294 }2295 res = MF_FAILED;2296 }2297 res = action_result(pfn, MF_MSG_BUDDY, res);2298 } else {2299 res = action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);2300 }2301 goto unlock_mutex;2302 } else if (res < 0) {2303 res = action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED);2304 goto unlock_mutex;2305 }2306 }2307 2308 folio = page_folio(p);2309 2310 /* filter pages that are protected from hwpoison test by users */2311 folio_lock(folio);2312 if (hwpoison_filter(p)) {2313 ClearPageHWPoison(p);2314 folio_unlock(folio);2315 folio_put(folio);2316 res = -EOPNOTSUPP;2317 goto unlock_mutex;2318 }2319 folio_unlock(folio);2320 2321 if (folio_test_large(folio)) {2322 /*2323 * The flag must be set after the refcount is bumped2324 * otherwise it may race with THP split.2325 * And the flag can't be set in get_hwpoison_page() since2326 * it is called by soft offline too and it is just called2327 * for !MF_COUNT_INCREASED. So here seems to be the best2328 * place.2329 *2330 * Don't need care about the above error handling paths for2331 * get_hwpoison_page() since they handle either free page2332 * or unhandlable page. The refcount is bumped iff the2333 * page is a valid handlable page.2334 */2335 folio_set_has_hwpoisoned(folio);2336 if (try_to_split_thp_page(p, false) < 0) {2337 res = -EHWPOISON;2338 kill_procs_now(p, pfn, flags, folio);2339 put_page(p);2340 action_result(pfn, MF_MSG_UNSPLIT_THP, MF_FAILED);2341 goto unlock_mutex;2342 }2343 VM_BUG_ON_PAGE(!page_count(p), p);2344 folio = page_folio(p);2345 }2346 2347 /*2348 * We ignore non-LRU pages for good reasons.2349 * - PG_locked is only well defined for LRU pages and a few others2350 * - to avoid races with __SetPageLocked()2351 * - to avoid races with __SetPageSlab*() (and more non-atomic ops)2352 * The check (unnecessarily) ignores LRU pages being isolated and2353 * walked by the page reclaim code, however that's not a big loss.2354 */2355 shake_folio(folio);2356 2357 folio_lock(folio);2358 2359 /*2360 * We're only intended to deal with the non-Compound page here.2361 * The page cannot become compound pages again as folio has been2362 * splited and extra refcnt is held.2363 */2364 WARN_ON(folio_test_large(folio));2365 2366 /*2367 * We use page flags to determine what action should be taken, but2368 * the flags can be modified by the error containment action. One2369 * example is an mlocked page, where PG_mlocked is cleared by2370 * folio_remove_rmap_*() in try_to_unmap_one(). So to determine page2371 * status correctly, we save a copy of the page flags at this time.2372 */2373 page_flags = folio->flags;2374 2375 /*2376 * __munlock_folio() may clear a writeback folio's LRU flag without2377 * the folio lock. We need to wait for writeback completion for this2378 * folio or it may trigger a vfs BUG while evicting inode.2379 */2380 if (!folio_test_lru(folio) && !folio_test_writeback(folio))2381 goto identify_page_state;2382 2383 /*2384 * It's very difficult to mess with pages currently under IO2385 * and in many cases impossible, so we just avoid it here.2386 */2387 folio_wait_writeback(folio);2388 2389 /*2390 * Now take care of user space mappings.2391 * Abort on fail: __filemap_remove_folio() assumes unmapped page.2392 */2393 if (!hwpoison_user_mappings(folio, p, pfn, flags)) {2394 res = action_result(pfn, MF_MSG_UNMAP_FAILED, MF_FAILED);2395 goto unlock_page;2396 }2397 2398 /*2399 * Torn down by someone else?2400 */2401 if (folio_test_lru(folio) && !folio_test_swapcache(folio) &&2402 folio->mapping == NULL) {2403 res = action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);2404 goto unlock_page;2405 }2406 2407identify_page_state:2408 res = identify_page_state(pfn, p, page_flags);2409 mutex_unlock(&mf_mutex);2410 return res;2411unlock_page:2412 folio_unlock(folio);2413unlock_mutex:2414 mutex_unlock(&mf_mutex);2415 return res;2416}2417EXPORT_SYMBOL_GPL(memory_failure);2418 2419#define MEMORY_FAILURE_FIFO_ORDER 42420#define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER)2421 2422struct memory_failure_entry {2423 unsigned long pfn;2424 int flags;2425};2426 2427struct memory_failure_cpu {2428 DECLARE_KFIFO(fifo, struct memory_failure_entry,2429 MEMORY_FAILURE_FIFO_SIZE);2430 raw_spinlock_t lock;2431 struct work_struct work;2432};2433 2434static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);2435 2436/**2437 * memory_failure_queue - Schedule handling memory failure of a page.2438 * @pfn: Page Number of the corrupted page2439 * @flags: Flags for memory failure handling2440 *2441 * This function is called by the low level hardware error handler2442 * when it detects hardware memory corruption of a page. It schedules2443 * the recovering of error page, including dropping pages, killing2444 * processes etc.2445 *2446 * The function is primarily of use for corruptions that2447 * happen outside the current execution context (e.g. when2448 * detected by a background scrubber)2449 *2450 * Can run in IRQ context.2451 */2452void memory_failure_queue(unsigned long pfn, int flags)2453{2454 struct memory_failure_cpu *mf_cpu;2455 unsigned long proc_flags;2456 bool buffer_overflow;2457 struct memory_failure_entry entry = {2458 .pfn = pfn,2459 .flags = flags,2460 };2461 2462 mf_cpu = &get_cpu_var(memory_failure_cpu);2463 raw_spin_lock_irqsave(&mf_cpu->lock, proc_flags);2464 buffer_overflow = !kfifo_put(&mf_cpu->fifo, entry);2465 if (!buffer_overflow)2466 schedule_work_on(smp_processor_id(), &mf_cpu->work);2467 raw_spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);2468 put_cpu_var(memory_failure_cpu);2469 if (buffer_overflow)2470 pr_err("buffer overflow when queuing memory failure at %#lx\n",2471 pfn);2472}2473EXPORT_SYMBOL_GPL(memory_failure_queue);2474 2475static void memory_failure_work_func(struct work_struct *work)2476{2477 struct memory_failure_cpu *mf_cpu;2478 struct memory_failure_entry entry = { 0, };2479 unsigned long proc_flags;2480 int gotten;2481 2482 mf_cpu = container_of(work, struct memory_failure_cpu, work);2483 for (;;) {2484 raw_spin_lock_irqsave(&mf_cpu->lock, proc_flags);2485 gotten = kfifo_get(&mf_cpu->fifo, &entry);2486 raw_spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);2487 if (!gotten)2488 break;2489 if (entry.flags & MF_SOFT_OFFLINE)2490 soft_offline_page(entry.pfn, entry.flags);2491 else2492 memory_failure(entry.pfn, entry.flags);2493 }2494}2495 2496/*2497 * Process memory_failure work queued on the specified CPU.2498 * Used to avoid return-to-userspace racing with the memory_failure workqueue.2499 */2500void memory_failure_queue_kick(int cpu)2501{2502 struct memory_failure_cpu *mf_cpu;2503 2504 mf_cpu = &per_cpu(memory_failure_cpu, cpu);2505 cancel_work_sync(&mf_cpu->work);2506 memory_failure_work_func(&mf_cpu->work);2507}2508 2509static int __init memory_failure_init(void)2510{2511 struct memory_failure_cpu *mf_cpu;2512 int cpu;2513 2514 for_each_possible_cpu(cpu) {2515 mf_cpu = &per_cpu(memory_failure_cpu, cpu);2516 raw_spin_lock_init(&mf_cpu->lock);2517 INIT_KFIFO(mf_cpu->fifo);2518 INIT_WORK(&mf_cpu->work, memory_failure_work_func);2519 }2520 2521 register_sysctl_init("vm", memory_failure_table);2522 2523 return 0;2524}2525core_initcall(memory_failure_init);2526 2527#undef pr_fmt2528#define pr_fmt(fmt) "Unpoison: " fmt2529#define unpoison_pr_info(fmt, pfn, rs) \2530({ \2531 if (__ratelimit(rs)) \2532 pr_info(fmt, pfn); \2533})2534 2535/**2536 * unpoison_memory - Unpoison a previously poisoned page2537 * @pfn: Page number of the to be unpoisoned page2538 *2539 * Software-unpoison a page that has been poisoned by2540 * memory_failure() earlier.2541 *2542 * This is only done on the software-level, so it only works2543 * for linux injected failures, not real hardware failures2544 *2545 * Returns 0 for success, otherwise -errno.2546 */2547int unpoison_memory(unsigned long pfn)2548{2549 struct folio *folio;2550 struct page *p;2551 int ret = -EBUSY, ghp;2552 unsigned long count;2553 bool huge = false;2554 static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,2555 DEFAULT_RATELIMIT_BURST);2556 2557 if (!pfn_valid(pfn))2558 return -ENXIO;2559 2560 p = pfn_to_page(pfn);2561 folio = page_folio(p);2562 2563 mutex_lock(&mf_mutex);2564 2565 if (hw_memory_failure) {2566 unpoison_pr_info("%#lx: disabled after HW memory failure\n",2567 pfn, &unpoison_rs);2568 ret = -EOPNOTSUPP;2569 goto unlock_mutex;2570 }2571 2572 if (is_huge_zero_folio(folio)) {2573 unpoison_pr_info("%#lx: huge zero page is not supported\n",2574 pfn, &unpoison_rs);2575 ret = -EOPNOTSUPP;2576 goto unlock_mutex;2577 }2578 2579 if (!PageHWPoison(p)) {2580 unpoison_pr_info("%#lx: page was already unpoisoned\n",2581 pfn, &unpoison_rs);2582 goto unlock_mutex;2583 }2584 2585 if (folio_ref_count(folio) > 1) {2586 unpoison_pr_info("%#lx: someone grabs the hwpoison page\n",2587 pfn, &unpoison_rs);2588 goto unlock_mutex;2589 }2590 2591 if (folio_test_slab(folio) || folio_test_pgtable(folio) ||2592 folio_test_reserved(folio) || folio_test_offline(folio))2593 goto unlock_mutex;2594 2595 if (folio_mapped(folio)) {2596 unpoison_pr_info("%#lx: someone maps the hwpoison page\n",2597 pfn, &unpoison_rs);2598 goto unlock_mutex;2599 }2600 2601 if (folio_mapping(folio)) {2602 unpoison_pr_info("%#lx: the hwpoison page has non-NULL mapping\n",2603 pfn, &unpoison_rs);2604 goto unlock_mutex;2605 }2606 2607 ghp = get_hwpoison_page(p, MF_UNPOISON);2608 if (!ghp) {2609 if (folio_test_hugetlb(folio)) {2610 huge = true;2611 count = folio_free_raw_hwp(folio, false);2612 if (count == 0)2613 goto unlock_mutex;2614 }2615 ret = folio_test_clear_hwpoison(folio) ? 0 : -EBUSY;2616 } else if (ghp < 0) {2617 if (ghp == -EHWPOISON) {2618 ret = put_page_back_buddy(p) ? 0 : -EBUSY;2619 } else {2620 ret = ghp;2621 unpoison_pr_info("%#lx: failed to grab page\n",2622 pfn, &unpoison_rs);2623 }2624 } else {2625 if (folio_test_hugetlb(folio)) {2626 huge = true;2627 count = folio_free_raw_hwp(folio, false);2628 if (count == 0) {2629 folio_put(folio);2630 goto unlock_mutex;2631 }2632 }2633 2634 folio_put(folio);2635 if (TestClearPageHWPoison(p)) {2636 folio_put(folio);2637 ret = 0;2638 }2639 }2640 2641unlock_mutex:2642 mutex_unlock(&mf_mutex);2643 if (!ret) {2644 if (!huge)2645 num_poisoned_pages_sub(pfn, 1);2646 unpoison_pr_info("%#lx: software-unpoisoned page\n",2647 page_to_pfn(p), &unpoison_rs);2648 }2649 return ret;2650}2651EXPORT_SYMBOL(unpoison_memory);2652 2653#undef pr_fmt2654#define pr_fmt(fmt) "Soft offline: " fmt2655 2656/*2657 * soft_offline_in_use_page handles hugetlb-pages and non-hugetlb pages.2658 * If the page is a non-dirty unmapped page-cache page, it simply invalidates.2659 * If the page is mapped, it migrates the contents over.2660 */2661static int soft_offline_in_use_page(struct page *page)2662{2663 long ret = 0;2664 unsigned long pfn = page_to_pfn(page);2665 struct folio *folio = page_folio(page);2666 char const *msg_page[] = {"page", "hugepage"};2667 bool huge = folio_test_hugetlb(folio);2668 bool isolated;2669 LIST_HEAD(pagelist);2670 struct migration_target_control mtc = {2671 .nid = NUMA_NO_NODE,2672 .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,2673 .reason = MR_MEMORY_FAILURE,2674 };2675 2676 if (!huge && folio_test_large(folio)) {2677 if (try_to_split_thp_page(page, true)) {2678 pr_info("%#lx: thp split failed\n", pfn);2679 return -EBUSY;2680 }2681 folio = page_folio(page);2682 }2683 2684 folio_lock(folio);2685 if (!huge)2686 folio_wait_writeback(folio);2687 if (PageHWPoison(page)) {2688 folio_unlock(folio);2689 folio_put(folio);2690 pr_info("%#lx: page already poisoned\n", pfn);2691 return 0;2692 }2693 2694 if (!huge && folio_test_lru(folio) && !folio_test_swapcache(folio))2695 /*2696 * Try to invalidate first. This should work for2697 * non dirty unmapped page cache pages.2698 */2699 ret = mapping_evict_folio(folio_mapping(folio), folio);2700 folio_unlock(folio);2701 2702 if (ret) {2703 pr_info("%#lx: invalidated\n", pfn);2704 page_handle_poison(page, false, true);2705 return 0;2706 }2707 2708 isolated = isolate_folio_to_list(folio, &pagelist);2709 2710 /*2711 * If we succeed to isolate the folio, we grabbed another refcount on2712 * the folio, so we can safely drop the one we got from get_any_page().2713 * If we failed to isolate the folio, it means that we cannot go further2714 * and we will return an error, so drop the reference we got from2715 * get_any_page() as well.2716 */2717 folio_put(folio);2718 2719 if (isolated) {2720 ret = migrate_pages(&pagelist, alloc_migration_target, NULL,2721 (unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_FAILURE, NULL);2722 if (!ret) {2723 bool release = !huge;2724 2725 if (!page_handle_poison(page, huge, release))2726 ret = -EBUSY;2727 } else {2728 if (!list_empty(&pagelist))2729 putback_movable_pages(&pagelist);2730 2731 pr_info("%#lx: %s migration failed %ld, type %pGp\n",2732 pfn, msg_page[huge], ret, &page->flags);2733 if (ret > 0)2734 ret = -EBUSY;2735 }2736 } else {2737 pr_info("%#lx: %s isolation failed, page count %d, type %pGp\n",2738 pfn, msg_page[huge], page_count(page), &page->flags);2739 ret = -EBUSY;2740 }2741 return ret;2742}2743 2744/**2745 * soft_offline_page - Soft offline a page.2746 * @pfn: pfn to soft-offline2747 * @flags: flags. Same as memory_failure().2748 *2749 * Returns 0 on success,2750 * -EOPNOTSUPP for hwpoison_filter() filtered the error event, or2751 * disabled by /proc/sys/vm/enable_soft_offline,2752 * < 0 otherwise negated errno.2753 *2754 * Soft offline a page, by migration or invalidation,2755 * without killing anything. This is for the case when2756 * a page is not corrupted yet (so it's still valid to access),2757 * but has had a number of corrected errors and is better taken2758 * out.2759 *2760 * The actual policy on when to do that is maintained by2761 * user space.2762 *2763 * This should never impact any application or cause data loss,2764 * however it might take some time.2765 *2766 * This is not a 100% solution for all memory, but tries to be2767 * ``good enough'' for the majority of memory.2768 */2769int soft_offline_page(unsigned long pfn, int flags)2770{2771 int ret;2772 bool try_again = true;2773 struct page *page;2774 2775 if (!pfn_valid(pfn)) {2776 WARN_ON_ONCE(flags & MF_COUNT_INCREASED);2777 return -ENXIO;2778 }2779 2780 /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */2781 page = pfn_to_online_page(pfn);2782 if (!page) {2783 put_ref_page(pfn, flags);2784 return -EIO;2785 }2786 2787 if (!sysctl_enable_soft_offline) {2788 pr_info_once("disabled by /proc/sys/vm/enable_soft_offline\n");2789 put_ref_page(pfn, flags);2790 return -EOPNOTSUPP;2791 }2792 2793 mutex_lock(&mf_mutex);2794 2795 if (PageHWPoison(page)) {2796 pr_info("%#lx: page already poisoned\n", pfn);2797 put_ref_page(pfn, flags);2798 mutex_unlock(&mf_mutex);2799 return 0;2800 }2801 2802retry:2803 get_online_mems();2804 ret = get_hwpoison_page(page, flags | MF_SOFT_OFFLINE);2805 put_online_mems();2806 2807 if (hwpoison_filter(page)) {2808 if (ret > 0)2809 put_page(page);2810 2811 mutex_unlock(&mf_mutex);2812 return -EOPNOTSUPP;2813 }2814 2815 if (ret > 0) {2816 ret = soft_offline_in_use_page(page);2817 } else if (ret == 0) {2818 if (!page_handle_poison(page, true, false)) {2819 if (try_again) {2820 try_again = false;2821 flags &= ~MF_COUNT_INCREASED;2822 goto retry;2823 }2824 ret = -EBUSY;2825 }2826 }2827 2828 mutex_unlock(&mf_mutex);2829 2830 return ret;2831}2832