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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (C) 2008, 2009 Intel Corporation
- * Authors: Andi Kleen, Fengguang Wu
- *
- * High level machine check handler. Handles pages reported by the
- * hardware as being corrupted usually due to a multi-bit ECC memory or cache
- * failure.
- *
- * In addition there is a "soft offline" entry point that allows stop using
- * not-yet-corrupted-by-suspicious pages without killing anything.
- *
- * Handles page cache pages in various states. The tricky part
- * here is that we can access any page asynchronously in respect to
- * other VM users, because memory failures could happen anytime and
- * anywhere. This could violate some of their assumptions. This is why
- * this code has to be extremely careful. Generally it tries to use
- * normal locking rules, as in get the standard locks, even if that means
- * the error handling takes potentially a long time.
- *
- * It can be very tempting to add handling for obscure cases here.
- * In general any code for handling new cases should only be added iff:
- * - You know how to test it.
- * - You have a test that can be added to mce-test
- * https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/
- * - The case actually shows up as a frequent (top 10) page state in
- * tools/vm/page-types when running a real workload.
- *
- * There are several operations here with exponential complexity because
- * of unsuitable VM data structures. For example the operation to map back
- * from RMAP chains to processes has to walk the complete process list and
- * has non linear complexity with the number. But since memory corruptions
- * are rare we hope to get away with this. This avoids impacting the core
- * VM.
- */
- #include <linux/kernel.h>
- #include <linux/mm.h>
- #include <linux/page-flags.h>
- #include <linux/kernel-page-flags.h>
- #include <linux/sched/signal.h>
- #include <linux/sched/task.h>
- #include <linux/ksm.h>
- #include <linux/rmap.h>
- #include <linux/export.h>
- #include <linux/pagemap.h>
- #include <linux/swap.h>
- #include <linux/backing-dev.h>
- #include <linux/migrate.h>
- #include <linux/suspend.h>
- #include <linux/slab.h>
- #include <linux/swapops.h>
- #include <linux/hugetlb.h>
- #include <linux/memory_hotplug.h>
- #include <linux/mm_inline.h>
- #include <linux/memremap.h>
- #include <linux/kfifo.h>
- #include <linux/ratelimit.h>
- #include <linux/page-isolation.h>
- #include "internal.h"
- #include "ras/ras_event.h"
- int sysctl_memory_failure_early_kill __read_mostly = 0;
- int sysctl_memory_failure_recovery __read_mostly = 1;
- atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
- static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
- {
- if (hugepage_or_freepage) {
- /*
- * Doing this check for free pages is also fine since dissolve_free_huge_page
- * returns 0 for non-hugetlb pages as well.
- */
- if (dissolve_free_huge_page(page) || !take_page_off_buddy(page))
- /*
- * We could fail to take off the target page from buddy
- * for example due to racy page allocaiton, but that's
- * acceptable because soft-offlined page is not broken
- * and if someone really want to use it, they should
- * take it.
- */
- return false;
- }
- SetPageHWPoison(page);
- if (release)
- put_page(page);
- page_ref_inc(page);
- num_poisoned_pages_inc();
- return true;
- }
- #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
- u32 hwpoison_filter_enable = 0;
- u32 hwpoison_filter_dev_major = ~0U;
- u32 hwpoison_filter_dev_minor = ~0U;
- u64 hwpoison_filter_flags_mask;
- u64 hwpoison_filter_flags_value;
- EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
- EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
- EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
- EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
- EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
- static int hwpoison_filter_dev(struct page *p)
- {
- struct address_space *mapping;
- dev_t dev;
- if (hwpoison_filter_dev_major == ~0U &&
- hwpoison_filter_dev_minor == ~0U)
- return 0;
- /*
- * page_mapping() does not accept slab pages.
- */
- if (PageSlab(p))
- return -EINVAL;
- mapping = page_mapping(p);
- if (mapping == NULL || mapping->host == NULL)
- return -EINVAL;
- dev = mapping->host->i_sb->s_dev;
- if (hwpoison_filter_dev_major != ~0U &&
- hwpoison_filter_dev_major != MAJOR(dev))
- return -EINVAL;
- if (hwpoison_filter_dev_minor != ~0U &&
- hwpoison_filter_dev_minor != MINOR(dev))
- return -EINVAL;
- return 0;
- }
- static int hwpoison_filter_flags(struct page *p)
- {
- if (!hwpoison_filter_flags_mask)
- return 0;
- if ((stable_page_flags(p) & hwpoison_filter_flags_mask) ==
- hwpoison_filter_flags_value)
- return 0;
- else
- return -EINVAL;
- }
- /*
- * This allows stress tests to limit test scope to a collection of tasks
- * by putting them under some memcg. This prevents killing unrelated/important
- * processes such as /sbin/init. Note that the target task may share clean
- * pages with init (eg. libc text), which is harmless. If the target task
- * share _dirty_ pages with another task B, the test scheme must make sure B
- * is also included in the memcg. At last, due to race conditions this filter
- * can only guarantee that the page either belongs to the memcg tasks, or is
- * a freed page.
- */
- #ifdef CONFIG_MEMCG
- u64 hwpoison_filter_memcg;
- EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
- static int hwpoison_filter_task(struct page *p)
- {
- if (!hwpoison_filter_memcg)
- return 0;
- if (page_cgroup_ino(p) != hwpoison_filter_memcg)
- return -EINVAL;
- return 0;
- }
- #else
- static int hwpoison_filter_task(struct page *p) { return 0; }
- #endif
- int hwpoison_filter(struct page *p)
- {
- if (!hwpoison_filter_enable)
- return 0;
- if (hwpoison_filter_dev(p))
- return -EINVAL;
- if (hwpoison_filter_flags(p))
- return -EINVAL;
- if (hwpoison_filter_task(p))
- return -EINVAL;
- return 0;
- }
- #else
- int hwpoison_filter(struct page *p)
- {
- return 0;
- }
- #endif
- EXPORT_SYMBOL_GPL(hwpoison_filter);
- /*
- * Kill all processes that have a poisoned page mapped and then isolate
- * the page.
- *
- * General strategy:
- * Find all processes having the page mapped and kill them.
- * But we keep a page reference around so that the page is not
- * actually freed yet.
- * Then stash the page away
- *
- * There's no convenient way to get back to mapped processes
- * from the VMAs. So do a brute-force search over all
- * running processes.
- *
- * Remember that machine checks are not common (or rather
- * if they are common you have other problems), so this shouldn't
- * be a performance issue.
- *
- * Also there are some races possible while we get from the
- * error detection to actually handle it.
- */
- struct to_kill {
- struct list_head nd;
- struct task_struct *tsk;
- unsigned long addr;
- short size_shift;
- };
- /*
- * Send all the processes who have the page mapped a signal.
- * ``action optional'' if they are not immediately affected by the error
- * ``action required'' if error happened in current execution context
- */
- static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
- {
- struct task_struct *t = tk->tsk;
- short addr_lsb = tk->size_shift;
- int ret = 0;
- pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
- pfn, t->comm, t->pid);
- if (flags & MF_ACTION_REQUIRED) {
- WARN_ON_ONCE(t != current);
- ret = force_sig_mceerr(BUS_MCEERR_AR,
- (void __user *)tk->addr, addr_lsb);
- } else {
- /*
- * Don't use force here, it's convenient if the signal
- * can be temporarily blocked.
- * This could cause a loop when the user sets SIGBUS
- * to SIG_IGN, but hopefully no one will do that?
- */
- ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
- addr_lsb, t); /* synchronous? */
- }
- if (ret < 0)
- pr_info("Memory failure: Error sending signal to %s:%d: %d\n",
- t->comm, t->pid, ret);
- return ret;
- }
- /*
- * When a unknown page type is encountered drain as many buffers as possible
- * in the hope to turn the page into a LRU or free page, which we can handle.
- */
- void shake_page(struct page *p, int access)
- {
- if (PageHuge(p))
- return;
- if (!PageSlab(p)) {
- lru_add_drain_all();
- if (PageLRU(p))
- return;
- drain_all_pages(page_zone(p));
- if (PageLRU(p) || is_free_buddy_page(p))
- return;
- }
- /*
- * Only call shrink_node_slabs here (which would also shrink
- * other caches) if access is not potentially fatal.
- */
- if (access)
- drop_slab_node(page_to_nid(p));
- }
- EXPORT_SYMBOL_GPL(shake_page);
- static unsigned long dev_pagemap_mapping_shift(struct page *page,
- struct vm_area_struct *vma)
- {
- unsigned long address = vma_address(page, vma);
- pgd_t *pgd;
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
- pgd = pgd_offset(vma->vm_mm, address);
- if (!pgd_present(*pgd))
- return 0;
- p4d = p4d_offset(pgd, address);
- if (!p4d_present(*p4d))
- return 0;
- pud = pud_offset(p4d, address);
- if (!pud_present(*pud))
- return 0;
- if (pud_devmap(*pud))
- return PUD_SHIFT;
- pmd = pmd_offset(pud, address);
- if (!pmd_present(*pmd))
- return 0;
- if (pmd_devmap(*pmd))
- return PMD_SHIFT;
- pte = pte_offset_map(pmd, address);
- if (!pte_present(*pte))
- return 0;
- if (pte_devmap(*pte))
- return PAGE_SHIFT;
- return 0;
- }
- /*
- * Failure handling: if we can't find or can't kill a process there's
- * not much we can do. We just print a message and ignore otherwise.
- */
- /*
- * Schedule a process for later kill.
- * Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
- */
- static void add_to_kill(struct task_struct *tsk, struct page *p,
- struct vm_area_struct *vma,
- struct list_head *to_kill)
- {
- struct to_kill *tk;
- tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
- if (!tk) {
- pr_err("Memory failure: Out of memory while machine check handling\n");
- return;
- }
- tk->addr = page_address_in_vma(p, vma);
- if (is_zone_device_page(p))
- tk->size_shift = dev_pagemap_mapping_shift(p, vma);
- else
- tk->size_shift = page_shift(compound_head(p));
- /*
- * Send SIGKILL if "tk->addr == -EFAULT". Also, as
- * "tk->size_shift" is always non-zero for !is_zone_device_page(),
- * so "tk->size_shift == 0" effectively checks no mapping on
- * ZONE_DEVICE. Indeed, when a devdax page is mmapped N times
- * to a process' address space, it's possible not all N VMAs
- * contain mappings for the page, but at least one VMA does.
- * Only deliver SIGBUS with payload derived from the VMA that
- * has a mapping for the page.
- */
- if (tk->addr == -EFAULT) {
- pr_info("Memory failure: Unable to find user space address %lx in %s\n",
- page_to_pfn(p), tsk->comm);
- } else if (tk->size_shift == 0) {
- kfree(tk);
- return;
- }
- get_task_struct(tsk);
- tk->tsk = tsk;
- list_add_tail(&tk->nd, to_kill);
- }
- /*
- * Kill the processes that have been collected earlier.
- *
- * Only do anything when DOIT is set, otherwise just free the list
- * (this is used for clean pages which do not need killing)
- * Also when FAIL is set do a force kill because something went
- * wrong earlier.
- */
- static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
- unsigned long pfn, int flags)
- {
- struct to_kill *tk, *next;
- list_for_each_entry_safe (tk, next, to_kill, nd) {
- if (forcekill) {
- /*
- * In case something went wrong with munmapping
- * make sure the process doesn't catch the
- * signal and then access the memory. Just kill it.
- */
- if (fail || tk->addr == -EFAULT) {
- pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
- pfn, tk->tsk->comm, tk->tsk->pid);
- do_send_sig_info(SIGKILL, SEND_SIG_PRIV,
- tk->tsk, PIDTYPE_PID);
- }
- /*
- * In theory the process could have mapped
- * something else on the address in-between. We could
- * check for that, but we need to tell the
- * process anyways.
- */
- else if (kill_proc(tk, pfn, flags) < 0)
- pr_err("Memory failure: %#lx: Cannot send advisory machine check signal to %s:%d\n",
- pfn, tk->tsk->comm, tk->tsk->pid);
- }
- put_task_struct(tk->tsk);
- kfree(tk);
- }
- }
- /*
- * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
- * on behalf of the thread group. Return task_struct of the (first found)
- * dedicated thread if found, and return NULL otherwise.
- *
- * We already hold read_lock(&tasklist_lock) in the caller, so we don't
- * have to call rcu_read_lock/unlock() in this function.
- */
- static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
- {
- struct task_struct *t;
- for_each_thread(tsk, t) {
- if (t->flags & PF_MCE_PROCESS) {
- if (t->flags & PF_MCE_EARLY)
- return t;
- } else {
- if (sysctl_memory_failure_early_kill)
- return t;
- }
- }
- return NULL;
- }
- /*
- * Determine whether a given process is "early kill" process which expects
- * to be signaled when some page under the process is hwpoisoned.
- * Return task_struct of the dedicated thread (main thread unless explicitly
- * specified) if the process is "early kill," and otherwise returns NULL.
- *
- * Note that the above is true for Action Optional case, but not for Action
- * Required case where SIGBUS should sent only to the current thread.
- */
- static struct task_struct *task_early_kill(struct task_struct *tsk,
- int force_early)
- {
- if (!tsk->mm)
- return NULL;
- if (force_early) {
- /*
- * Comparing ->mm here because current task might represent
- * a subthread, while tsk always points to the main thread.
- */
- if (tsk->mm == current->mm)
- return current;
- else
- return NULL;
- }
- return find_early_kill_thread(tsk);
- }
- /*
- * Collect processes when the error hit an anonymous page.
- */
- static void collect_procs_anon(struct page *page, struct list_head *to_kill,
- int force_early)
- {
- struct vm_area_struct *vma;
- struct task_struct *tsk;
- struct anon_vma *av;
- pgoff_t pgoff;
- av = page_lock_anon_vma_read(page);
- if (av == NULL) /* Not actually mapped anymore */
- return;
- pgoff = page_to_pgoff(page);
- read_lock(&tasklist_lock);
- for_each_process (tsk) {
- struct anon_vma_chain *vmac;
- struct task_struct *t = task_early_kill(tsk, force_early);
- if (!t)
- continue;
- anon_vma_interval_tree_foreach(vmac, &av->rb_root,
- pgoff, pgoff) {
- vma = vmac->vma;
- if (!page_mapped_in_vma(page, vma))
- continue;
- if (vma->vm_mm == t->mm)
- add_to_kill(t, page, vma, to_kill);
- }
- }
- read_unlock(&tasklist_lock);
- page_unlock_anon_vma_read(av);
- }
- /*
- * Collect processes when the error hit a file mapped page.
- */
- static void collect_procs_file(struct page *page, struct list_head *to_kill,
- int force_early)
- {
- struct vm_area_struct *vma;
- struct task_struct *tsk;
- struct address_space *mapping = page->mapping;
- pgoff_t pgoff;
- i_mmap_lock_read(mapping);
- read_lock(&tasklist_lock);
- pgoff = page_to_pgoff(page);
- for_each_process(tsk) {
- struct task_struct *t = task_early_kill(tsk, force_early);
- if (!t)
- continue;
- vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
- pgoff) {
- /*
- * Send early kill signal to tasks where a vma covers
- * the page but the corrupted page is not necessarily
- * mapped it in its pte.
- * Assume applications who requested early kill want
- * to be informed of all such data corruptions.
- */
- if (vma->vm_mm == t->mm)
- add_to_kill(t, page, vma, to_kill);
- }
- }
- read_unlock(&tasklist_lock);
- i_mmap_unlock_read(mapping);
- }
- /*
- * Collect the processes who have the corrupted page mapped to kill.
- */
- static void collect_procs(struct page *page, struct list_head *tokill,
- int force_early)
- {
- if (!page->mapping)
- return;
- if (PageAnon(page))
- collect_procs_anon(page, tokill, force_early);
- else
- collect_procs_file(page, tokill, force_early);
- }
- static const char *action_name[] = {
- [MF_IGNORED] = "Ignored",
- [MF_FAILED] = "Failed",
- [MF_DELAYED] = "Delayed",
- [MF_RECOVERED] = "Recovered",
- };
- static const char * const action_page_types[] = {
- [MF_MSG_KERNEL] = "reserved kernel page",
- [MF_MSG_KERNEL_HIGH_ORDER] = "high-order kernel page",
- [MF_MSG_SLAB] = "kernel slab page",
- [MF_MSG_DIFFERENT_COMPOUND] = "different compound page after locking",
- [MF_MSG_POISONED_HUGE] = "huge page already hardware poisoned",
- [MF_MSG_HUGE] = "huge page",
- [MF_MSG_FREE_HUGE] = "free huge page",
- [MF_MSG_NON_PMD_HUGE] = "non-pmd-sized huge page",
- [MF_MSG_UNMAP_FAILED] = "unmapping failed page",
- [MF_MSG_DIRTY_SWAPCACHE] = "dirty swapcache page",
- [MF_MSG_CLEAN_SWAPCACHE] = "clean swapcache page",
- [MF_MSG_DIRTY_MLOCKED_LRU] = "dirty mlocked LRU page",
- [MF_MSG_CLEAN_MLOCKED_LRU] = "clean mlocked LRU page",
- [MF_MSG_DIRTY_UNEVICTABLE_LRU] = "dirty unevictable LRU page",
- [MF_MSG_CLEAN_UNEVICTABLE_LRU] = "clean unevictable LRU page",
- [MF_MSG_DIRTY_LRU] = "dirty LRU page",
- [MF_MSG_CLEAN_LRU] = "clean LRU page",
- [MF_MSG_TRUNCATED_LRU] = "already truncated LRU page",
- [MF_MSG_BUDDY] = "free buddy page",
- [MF_MSG_BUDDY_2ND] = "free buddy page (2nd try)",
- [MF_MSG_DAX] = "dax page",
- [MF_MSG_UNSPLIT_THP] = "unsplit thp",
- [MF_MSG_UNKNOWN] = "unknown page",
- };
- /*
- * XXX: It is possible that a page is isolated from LRU cache,
- * and then kept in swap cache or failed to remove from page cache.
- * The page count will stop it from being freed by unpoison.
- * Stress tests should be aware of this memory leak problem.
- */
- static int delete_from_lru_cache(struct page *p)
- {
- if (!isolate_lru_page(p)) {
- /*
- * Clear sensible page flags, so that the buddy system won't
- * complain when the page is unpoison-and-freed.
- */
- ClearPageActive(p);
- ClearPageUnevictable(p);
- /*
- * Poisoned page might never drop its ref count to 0 so we have
- * to uncharge it manually from its memcg.
- */
- mem_cgroup_uncharge(p);
- /*
- * drop the page count elevated by isolate_lru_page()
- */
- put_page(p);
- return 0;
- }
- return -EIO;
- }
- static int truncate_error_page(struct page *p, unsigned long pfn,
- struct address_space *mapping)
- {
- int ret = MF_FAILED;
- if (mapping->a_ops->error_remove_page) {
- int err = mapping->a_ops->error_remove_page(mapping, p);
- if (err != 0) {
- pr_info("Memory failure: %#lx: Failed to punch page: %d\n",
- pfn, err);
- } else if (page_has_private(p) &&
- !try_to_release_page(p, GFP_NOIO)) {
- pr_info("Memory failure: %#lx: failed to release buffers\n",
- pfn);
- } else {
- ret = MF_RECOVERED;
- }
- } else {
- /*
- * If the file system doesn't support it just invalidate
- * This fails on dirty or anything with private pages
- */
- if (invalidate_inode_page(p))
- ret = MF_RECOVERED;
- else
- pr_info("Memory failure: %#lx: Failed to invalidate\n",
- pfn);
- }
- return ret;
- }
- /*
- * Error hit kernel page.
- * Do nothing, try to be lucky and not touch this instead. For a few cases we
- * could be more sophisticated.
- */
- static int me_kernel(struct page *p, unsigned long pfn)
- {
- return MF_IGNORED;
- }
- /*
- * Page in unknown state. Do nothing.
- */
- static int me_unknown(struct page *p, unsigned long pfn)
- {
- pr_err("Memory failure: %#lx: Unknown page state\n", pfn);
- return MF_FAILED;
- }
- /*
- * Clean (or cleaned) page cache page.
- */
- static int me_pagecache_clean(struct page *p, unsigned long pfn)
- {
- struct address_space *mapping;
- delete_from_lru_cache(p);
- /*
- * For anonymous pages we're done the only reference left
- * should be the one m_f() holds.
- */
- if (PageAnon(p))
- return MF_RECOVERED;
- /*
- * Now truncate the page in the page cache. This is really
- * more like a "temporary hole punch"
- * Don't do this for block devices when someone else
- * has a reference, because it could be file system metadata
- * and that's not safe to truncate.
- */
- mapping = page_mapping(p);
- if (!mapping) {
- /*
- * Page has been teared down in the meanwhile
- */
- return MF_FAILED;
- }
- /*
- * Truncation is a bit tricky. Enable it per file system for now.
- *
- * Open: to take i_mutex or not for this? Right now we don't.
- */
- return truncate_error_page(p, pfn, mapping);
- }
- /*
- * Dirty pagecache page
- * Issues: when the error hit a hole page the error is not properly
- * propagated.
- */
- static int me_pagecache_dirty(struct page *p, unsigned long pfn)
- {
- struct address_space *mapping = page_mapping(p);
- SetPageError(p);
- /* TBD: print more information about the file. */
- if (mapping) {
- /*
- * IO error will be reported by write(), fsync(), etc.
- * who check the mapping.
- * This way the application knows that something went
- * wrong with its dirty file data.
- *
- * There's one open issue:
- *
- * The EIO will be only reported on the next IO
- * operation and then cleared through the IO map.
- * Normally Linux has two mechanisms to pass IO error
- * first through the AS_EIO flag in the address space
- * and then through the PageError flag in the page.
- * Since we drop pages on memory failure handling the
- * only mechanism open to use is through AS_AIO.
- *
- * This has the disadvantage that it gets cleared on
- * the first operation that returns an error, while
- * the PageError bit is more sticky and only cleared
- * when the page is reread or dropped. If an
- * application assumes it will always get error on
- * fsync, but does other operations on the fd before
- * and the page is dropped between then the error
- * will not be properly reported.
- *
- * This can already happen even without hwpoisoned
- * pages: first on metadata IO errors (which only
- * report through AS_EIO) or when the page is dropped
- * at the wrong time.
- *
- * So right now we assume that the application DTRT on
- * the first EIO, but we're not worse than other parts
- * of the kernel.
- */
- mapping_set_error(mapping, -EIO);
- }
- return me_pagecache_clean(p, pfn);
- }
- /*
- * Clean and dirty swap cache.
- *
- * Dirty swap cache page is tricky to handle. The page could live both in page
- * cache and swap cache(ie. page is freshly swapped in). So it could be
- * referenced concurrently by 2 types of PTEs:
- * normal PTEs and swap PTEs. We try to handle them consistently by calling
- * try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
- * and then
- * - clear dirty bit to prevent IO
- * - remove from LRU
- * - but keep in the swap cache, so that when we return to it on
- * a later page fault, we know the application is accessing
- * corrupted data and shall be killed (we installed simple
- * interception code in do_swap_page to catch it).
- *
- * Clean swap cache pages can be directly isolated. A later page fault will
- * bring in the known good data from disk.
- */
- static int me_swapcache_dirty(struct page *p, unsigned long pfn)
- {
- ClearPageDirty(p);
- /* Trigger EIO in shmem: */
- ClearPageUptodate(p);
- if (!delete_from_lru_cache(p))
- return MF_DELAYED;
- else
- return MF_FAILED;
- }
- static int me_swapcache_clean(struct page *p, unsigned long pfn)
- {
- delete_from_swap_cache(p);
- if (!delete_from_lru_cache(p))
- return MF_RECOVERED;
- else
- return MF_FAILED;
- }
- /*
- * Huge pages. Needs work.
- * Issues:
- * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
- * To narrow down kill region to one page, we need to break up pmd.
- */
- static int me_huge_page(struct page *p, unsigned long pfn)
- {
- int res = 0;
- struct page *hpage = compound_head(p);
- struct address_space *mapping;
- if (!PageHuge(hpage))
- return MF_DELAYED;
- mapping = page_mapping(hpage);
- if (mapping) {
- res = truncate_error_page(hpage, pfn, mapping);
- } else {
- unlock_page(hpage);
- /*
- * migration entry prevents later access on error anonymous
- * hugepage, so we can free and dissolve it into buddy to
- * save healthy subpages.
- */
- if (PageAnon(hpage))
- put_page(hpage);
- dissolve_free_huge_page(p);
- res = MF_RECOVERED;
- lock_page(hpage);
- }
- return res;
- }
- /*
- * Various page states we can handle.
- *
- * A page state is defined by its current page->flags bits.
- * The table matches them in order and calls the right handler.
- *
- * This is quite tricky because we can access page at any time
- * in its live cycle, so all accesses have to be extremely careful.
- *
- * This is not complete. More states could be added.
- * For any missing state don't attempt recovery.
- */
- #define dirty (1UL << PG_dirty)
- #define sc ((1UL << PG_swapcache) | (1UL << PG_swapbacked))
- #define unevict (1UL << PG_unevictable)
- #define mlock (1UL << PG_mlocked)
- #define lru (1UL << PG_lru)
- #define head (1UL << PG_head)
- #define slab (1UL << PG_slab)
- #define reserved (1UL << PG_reserved)
- static struct page_state {
- unsigned long mask;
- unsigned long res;
- enum mf_action_page_type type;
- int (*action)(struct page *p, unsigned long pfn);
- } error_states[] = {
- { reserved, reserved, MF_MSG_KERNEL, me_kernel },
- /*
- * free pages are specially detected outside this table:
- * PG_buddy pages only make a small fraction of all free pages.
- */
- /*
- * Could in theory check if slab page is free or if we can drop
- * currently unused objects without touching them. But just
- * treat it as standard kernel for now.
- */
- { slab, slab, MF_MSG_SLAB, me_kernel },
- { head, head, MF_MSG_HUGE, me_huge_page },
- { sc|dirty, sc|dirty, MF_MSG_DIRTY_SWAPCACHE, me_swapcache_dirty },
- { sc|dirty, sc, MF_MSG_CLEAN_SWAPCACHE, me_swapcache_clean },
- { mlock|dirty, mlock|dirty, MF_MSG_DIRTY_MLOCKED_LRU, me_pagecache_dirty },
- { mlock|dirty, mlock, MF_MSG_CLEAN_MLOCKED_LRU, me_pagecache_clean },
- { unevict|dirty, unevict|dirty, MF_MSG_DIRTY_UNEVICTABLE_LRU, me_pagecache_dirty },
- { unevict|dirty, unevict, MF_MSG_CLEAN_UNEVICTABLE_LRU, me_pagecache_clean },
- { lru|dirty, lru|dirty, MF_MSG_DIRTY_LRU, me_pagecache_dirty },
- { lru|dirty, lru, MF_MSG_CLEAN_LRU, me_pagecache_clean },
- /*
- * Catchall entry: must be at end.
- */
- { 0, 0, MF_MSG_UNKNOWN, me_unknown },
- };
- #undef dirty
- #undef sc
- #undef unevict
- #undef mlock
- #undef lru
- #undef head
- #undef slab
- #undef reserved
- /*
- * "Dirty/Clean" indication is not 100% accurate due to the possibility of
- * setting PG_dirty outside page lock. See also comment above set_page_dirty().
- */
- static void action_result(unsigned long pfn, enum mf_action_page_type type,
- enum mf_result result)
- {
- trace_memory_failure_event(pfn, type, result);
- pr_err("Memory failure: %#lx: recovery action for %s: %s\n",
- pfn, action_page_types[type], action_name[result]);
- }
- static int page_action(struct page_state *ps, struct page *p,
- unsigned long pfn)
- {
- int result;
- int count;
- result = ps->action(p, pfn);
- count = page_count(p) - 1;
- if (ps->action == me_swapcache_dirty && result == MF_DELAYED)
- count--;
- if (count > 0) {
- pr_err("Memory failure: %#lx: %s still referenced by %d users\n",
- pfn, action_page_types[ps->type], count);
- result = MF_FAILED;
- }
- action_result(pfn, ps->type, result);
- /* Could do more checks here if page looks ok */
- /*
- * Could adjust zone counters here to correct for the missing page.
- */
- return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
- }
- /**
- * get_hwpoison_page() - Get refcount for memory error handling:
- * @page: raw error page (hit by memory error)
- *
- * Return: return 0 if failed to grab the refcount, otherwise true (some
- * non-zero value.)
- */
- static int get_hwpoison_page(struct page *page)
- {
- struct page *head = compound_head(page);
- if (!PageHuge(head) && PageTransHuge(head)) {
- /*
- * Non anonymous thp exists only in allocation/free time. We
- * can't handle such a case correctly, so let's give it up.
- * This should be better than triggering BUG_ON when kernel
- * tries to touch the "partially handled" page.
- */
- if (!PageAnon(head)) {
- pr_err("Memory failure: %#lx: non anonymous thp\n",
- page_to_pfn(page));
- return 0;
- }
- }
- if (get_page_unless_zero(head)) {
- if (head == compound_head(page))
- return 1;
- pr_info("Memory failure: %#lx cannot catch tail\n",
- page_to_pfn(page));
- put_page(head);
- }
- return 0;
- }
- /*
- * Do all that is necessary to remove user space mappings. Unmap
- * the pages and send SIGBUS to the processes if the data was dirty.
- */
- static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
- int flags, struct page **hpagep)
- {
- enum ttu_flags ttu = TTU_IGNORE_MLOCK;
- struct address_space *mapping;
- LIST_HEAD(tokill);
- bool unmap_success = true;
- int kill = 1, forcekill;
- struct page *hpage = *hpagep;
- bool mlocked = PageMlocked(hpage);
- /*
- * Here we are interested only in user-mapped pages, so skip any
- * other types of pages.
- */
- if (PageReserved(p) || PageSlab(p))
- return true;
- if (!(PageLRU(hpage) || PageHuge(p)))
- return true;
- /*
- * This check implies we don't kill processes if their pages
- * are in the swap cache early. Those are always late kills.
- */
- if (!page_mapped(hpage))
- return true;
- if (PageKsm(p)) {
- pr_err("Memory failure: %#lx: can't handle KSM pages.\n", pfn);
- return false;
- }
- if (PageSwapCache(p)) {
- pr_err("Memory failure: %#lx: keeping poisoned page in swap cache\n",
- pfn);
- ttu |= TTU_IGNORE_HWPOISON;
- }
- /*
- * Propagate the dirty bit from PTEs to struct page first, because we
- * need this to decide if we should kill or just drop the page.
- * XXX: the dirty test could be racy: set_page_dirty() may not always
- * be called inside page lock (it's recommended but not enforced).
- */
- mapping = page_mapping(hpage);
- if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
- mapping_can_writeback(mapping)) {
- if (page_mkclean(hpage)) {
- SetPageDirty(hpage);
- } else {
- kill = 0;
- ttu |= TTU_IGNORE_HWPOISON;
- pr_info("Memory failure: %#lx: corrupted page was clean: dropped without side effects\n",
- pfn);
- }
- }
- /*
- * First collect all the processes that have the page
- * mapped in dirty form. This has to be done before try_to_unmap,
- * because ttu takes the rmap data structures down.
- *
- * Error handling: We ignore errors here because
- * there's nothing that can be done.
- */
- if (kill)
- collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
- if (!PageHuge(hpage)) {
- unmap_success = try_to_unmap(hpage, ttu);
- } else {
- if (!PageAnon(hpage)) {
- /*
- * For hugetlb pages in shared mappings, try_to_unmap
- * could potentially call huge_pmd_unshare. Because of
- * this, take semaphore in write mode here and set
- * TTU_RMAP_LOCKED to indicate we have taken the lock
- * at this higer level.
- */
- mapping = hugetlb_page_mapping_lock_write(hpage);
- if (mapping) {
- unmap_success = try_to_unmap(hpage,
- ttu|TTU_RMAP_LOCKED);
- i_mmap_unlock_write(mapping);
- } else {
- pr_info("Memory failure: %#lx: could not lock mapping for mapped huge page\n", pfn);
- unmap_success = false;
- }
- } else {
- unmap_success = try_to_unmap(hpage, ttu);
- }
- }
- if (!unmap_success)
- pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n",
- pfn, page_mapcount(hpage));
- /*
- * try_to_unmap() might put mlocked page in lru cache, so call
- * shake_page() again to ensure that it's flushed.
- */
- if (mlocked)
- shake_page(hpage, 0);
- /*
- * Now that the dirty bit has been propagated to the
- * struct page and all unmaps done we can decide if
- * killing is needed or not. Only kill when the page
- * was dirty or the process is not restartable,
- * otherwise the tokill list is merely
- * freed. When there was a problem unmapping earlier
- * use a more force-full uncatchable kill to prevent
- * any accesses to the poisoned memory.
- */
- forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
- kill_procs(&tokill, forcekill, !unmap_success, pfn, flags);
- return unmap_success;
- }
- static int identify_page_state(unsigned long pfn, struct page *p,
- unsigned long page_flags)
- {
- struct page_state *ps;
- /*
- * The first check uses the current page flags which may not have any
- * relevant information. The second check with the saved page flags is
- * carried out only if the first check can't determine the page status.
- */
- for (ps = error_states;; ps++)
- if ((p->flags & ps->mask) == ps->res)
- break;
- page_flags |= (p->flags & (1UL << PG_dirty));
- if (!ps->mask)
- for (ps = error_states;; ps++)
- if ((page_flags & ps->mask) == ps->res)
- break;
- return page_action(ps, p, pfn);
- }
- static int try_to_split_thp_page(struct page *page, const char *msg)
- {
- lock_page(page);
- if (!PageAnon(page) || unlikely(split_huge_page(page))) {
- unsigned long pfn = page_to_pfn(page);
- unlock_page(page);
- if (!PageAnon(page))
- pr_info("%s: %#lx: non anonymous thp\n", msg, pfn);
- else
- pr_info("%s: %#lx: thp split failed\n", msg, pfn);
- put_page(page);
- return -EBUSY;
- }
- unlock_page(page);
- return 0;
- }
- static int memory_failure_hugetlb(unsigned long pfn, int flags)
- {
- struct page *p = pfn_to_page(pfn);
- struct page *head = compound_head(p);
- int res;
- unsigned long page_flags;
- if (TestSetPageHWPoison(head)) {
- pr_err("Memory failure: %#lx: already hardware poisoned\n",
- pfn);
- return 0;
- }
- num_poisoned_pages_inc();
- if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
- /*
- * Check "filter hit" and "race with other subpage."
- */
- lock_page(head);
- if (PageHWPoison(head)) {
- if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
- || (p != head && TestSetPageHWPoison(head))) {
- num_poisoned_pages_dec();
- unlock_page(head);
- return 0;
- }
- }
- unlock_page(head);
- dissolve_free_huge_page(p);
- action_result(pfn, MF_MSG_FREE_HUGE, MF_DELAYED);
- return 0;
- }
- lock_page(head);
- page_flags = head->flags;
- if (!PageHWPoison(head)) {
- pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
- num_poisoned_pages_dec();
- unlock_page(head);
- put_page(head);
- return 0;
- }
- /*
- * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so
- * simply disable it. In order to make it work properly, we need
- * make sure that:
- * - conversion of a pud that maps an error hugetlb into hwpoison
- * entry properly works, and
- * - other mm code walking over page table is aware of pud-aligned
- * hwpoison entries.
- */
- if (huge_page_size(page_hstate(head)) > PMD_SIZE) {
- action_result(pfn, MF_MSG_NON_PMD_HUGE, MF_IGNORED);
- res = -EBUSY;
- goto out;
- }
- if (!hwpoison_user_mappings(p, pfn, flags, &head)) {
- action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
- res = -EBUSY;
- goto out;
- }
- res = identify_page_state(pfn, p, page_flags);
- out:
- unlock_page(head);
- return res;
- }
- static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
- struct dev_pagemap *pgmap)
- {
- struct page *page = pfn_to_page(pfn);
- const bool unmap_success = true;
- unsigned long size = 0;
- struct to_kill *tk;
- LIST_HEAD(tokill);
- int rc = -EBUSY;
- loff_t start;
- dax_entry_t cookie;
- if (flags & MF_COUNT_INCREASED)
- /*
- * Drop the extra refcount in case we come from madvise().
- */
- put_page(page);
- /* device metadata space is not recoverable */
- if (!pgmap_pfn_valid(pgmap, pfn)) {
- rc = -ENXIO;
- goto out;
- }
- /*
- * Prevent the inode from being freed while we are interrogating
- * the address_space, typically this would be handled by
- * lock_page(), but dax pages do not use the page lock. This
- * also prevents changes to the mapping of this pfn until
- * poison signaling is complete.
- */
- cookie = dax_lock_page(page);
- if (!cookie)
- goto out;
- if (hwpoison_filter(page)) {
- rc = 0;
- goto unlock;
- }
- if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
- /*
- * TODO: Handle HMM pages which may need coordination
- * with device-side memory.
- */
- goto unlock;
- }
- /*
- * Use this flag as an indication that the dax page has been
- * remapped UC to prevent speculative consumption of poison.
- */
- SetPageHWPoison(page);
- /*
- * Unlike System-RAM there is no possibility to swap in a
- * different physical page at a given virtual address, so all
- * userspace consumption of ZONE_DEVICE memory necessitates
- * SIGBUS (i.e. MF_MUST_KILL)
- */
- flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
- collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED);
- list_for_each_entry(tk, &tokill, nd)
- if (tk->size_shift)
- size = max(size, 1UL << tk->size_shift);
- if (size) {
- /*
- * Unmap the largest mapping to avoid breaking up
- * device-dax mappings which are constant size. The
- * actual size of the mapping being torn down is
- * communicated in siginfo, see kill_proc()
- */
- start = (page->index << PAGE_SHIFT) & ~(size - 1);
- unmap_mapping_range(page->mapping, start, size, 0);
- }
- kill_procs(&tokill, flags & MF_MUST_KILL, !unmap_success, pfn, flags);
- rc = 0;
- unlock:
- dax_unlock_page(page, cookie);
- out:
- /* drop pgmap ref acquired in caller */
- put_dev_pagemap(pgmap);
- action_result(pfn, MF_MSG_DAX, rc ? MF_FAILED : MF_RECOVERED);
- return rc;
- }
- /**
- * memory_failure - Handle memory failure of a page.
- * @pfn: Page Number of the corrupted page
- * @flags: fine tune action taken
- *
- * This function is called by the low level machine check code
- * of an architecture when it detects hardware memory corruption
- * of a page. It tries its best to recover, which includes
- * dropping pages, killing processes etc.
- *
- * The function is primarily of use for corruptions that
- * happen outside the current execution context (e.g. when
- * detected by a background scrubber)
- *
- * Must run in process context (e.g. a work queue) with interrupts
- * enabled and no spinlocks hold.
- */
- int memory_failure(unsigned long pfn, int flags)
- {
- struct page *p;
- struct page *hpage;
- struct page *orig_head;
- struct dev_pagemap *pgmap;
- int res;
- unsigned long page_flags;
- if (!sysctl_memory_failure_recovery)
- panic("Memory failure on page %lx", pfn);
- p = pfn_to_online_page(pfn);
- if (!p) {
- if (pfn_valid(pfn)) {
- pgmap = get_dev_pagemap(pfn, NULL);
- if (pgmap)
- return memory_failure_dev_pagemap(pfn, flags,
- pgmap);
- }
- pr_err("Memory failure: %#lx: memory outside kernel control\n",
- pfn);
- return -ENXIO;
- }
- if (PageHuge(p))
- return memory_failure_hugetlb(pfn, flags);
- if (TestSetPageHWPoison(p)) {
- pr_err("Memory failure: %#lx: already hardware poisoned\n",
- pfn);
- return 0;
- }
- orig_head = hpage = compound_head(p);
- num_poisoned_pages_inc();
- /*
- * We need/can do nothing about count=0 pages.
- * 1) it's a free page, and therefore in safe hand:
- * prep_new_page() will be the gate keeper.
- * 2) it's part of a non-compound high order page.
- * Implies some kernel user: cannot stop them from
- * R/W the page; let's pray that the page has been
- * used and will be freed some time later.
- * In fact it's dangerous to directly bump up page count from 0,
- * that may make page_ref_freeze()/page_ref_unfreeze() mismatch.
- */
- if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
- if (is_free_buddy_page(p)) {
- action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
- return 0;
- } else {
- action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
- return -EBUSY;
- }
- }
- if (PageTransHuge(hpage)) {
- if (try_to_split_thp_page(p, "Memory Failure") < 0) {
- action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
- return -EBUSY;
- }
- VM_BUG_ON_PAGE(!page_count(p), p);
- }
- /*
- * We ignore non-LRU pages for good reasons.
- * - PG_locked is only well defined for LRU pages and a few others
- * - to avoid races with __SetPageLocked()
- * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
- * The check (unnecessarily) ignores LRU pages being isolated and
- * walked by the page reclaim code, however that's not a big loss.
- */
- shake_page(p, 0);
- /* shake_page could have turned it free. */
- if (!PageLRU(p) && is_free_buddy_page(p)) {
- if (flags & MF_COUNT_INCREASED)
- action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
- else
- action_result(pfn, MF_MSG_BUDDY_2ND, MF_DELAYED);
- return 0;
- }
- lock_page(p);
- /*
- * The page could have changed compound pages during the locking.
- * If this happens just bail out.
- */
- if (PageCompound(p) && compound_head(p) != orig_head) {
- action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
- res = -EBUSY;
- goto out;
- }
- /*
- * We use page flags to determine what action should be taken, but
- * the flags can be modified by the error containment action. One
- * example is an mlocked page, where PG_mlocked is cleared by
- * page_remove_rmap() in try_to_unmap_one(). So to determine page status
- * correctly, we save a copy of the page flags at this time.
- */
- page_flags = p->flags;
- /*
- * unpoison always clear PG_hwpoison inside page lock
- */
- if (!PageHWPoison(p)) {
- pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
- num_poisoned_pages_dec();
- unlock_page(p);
- put_page(p);
- return 0;
- }
- if (hwpoison_filter(p)) {
- if (TestClearPageHWPoison(p))
- num_poisoned_pages_dec();
- unlock_page(p);
- put_page(p);
- return 0;
- }
- /*
- * __munlock_pagevec may clear a writeback page's LRU flag without
- * page_lock. We need wait writeback completion for this page or it
- * may trigger vfs BUG while evict inode.
- */
- if (!PageTransTail(p) && !PageLRU(p) && !PageWriteback(p))
- goto identify_page_state;
- /*
- * It's very difficult to mess with pages currently under IO
- * and in many cases impossible, so we just avoid it here.
- */
- wait_on_page_writeback(p);
- /*
- * Now take care of user space mappings.
- * Abort on fail: __delete_from_page_cache() assumes unmapped page.
- */
- if (!hwpoison_user_mappings(p, pfn, flags, &p)) {
- action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
- res = -EBUSY;
- goto out;
- }
- /*
- * Torn down by someone else?
- */
- if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
- action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
- res = -EBUSY;
- goto out;
- }
- identify_page_state:
- res = identify_page_state(pfn, p, page_flags);
- out:
- unlock_page(p);
- return res;
- }
- EXPORT_SYMBOL_GPL(memory_failure);
- #define MEMORY_FAILURE_FIFO_ORDER 4
- #define MEMORY_FAILURE_FIFO_SIZE (1 << MEMORY_FAILURE_FIFO_ORDER)
- struct memory_failure_entry {
- unsigned long pfn;
- int flags;
- };
- struct memory_failure_cpu {
- DECLARE_KFIFO(fifo, struct memory_failure_entry,
- MEMORY_FAILURE_FIFO_SIZE);
- spinlock_t lock;
- struct work_struct work;
- };
- static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);
- /**
- * memory_failure_queue - Schedule handling memory failure of a page.
- * @pfn: Page Number of the corrupted page
- * @flags: Flags for memory failure handling
- *
- * This function is called by the low level hardware error handler
- * when it detects hardware memory corruption of a page. It schedules
- * the recovering of error page, including dropping pages, killing
- * processes etc.
- *
- * The function is primarily of use for corruptions that
- * happen outside the current execution context (e.g. when
- * detected by a background scrubber)
- *
- * Can run in IRQ context.
- */
- void memory_failure_queue(unsigned long pfn, int flags)
- {
- struct memory_failure_cpu *mf_cpu;
- unsigned long proc_flags;
- struct memory_failure_entry entry = {
- .pfn = pfn,
- .flags = flags,
- };
- mf_cpu = &get_cpu_var(memory_failure_cpu);
- spin_lock_irqsave(&mf_cpu->lock, proc_flags);
- if (kfifo_put(&mf_cpu->fifo, entry))
- schedule_work_on(smp_processor_id(), &mf_cpu->work);
- else
- pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n",
- pfn);
- spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
- put_cpu_var(memory_failure_cpu);
- }
- EXPORT_SYMBOL_GPL(memory_failure_queue);
- static void memory_failure_work_func(struct work_struct *work)
- {
- struct memory_failure_cpu *mf_cpu;
- struct memory_failure_entry entry = { 0, };
- unsigned long proc_flags;
- int gotten;
- mf_cpu = container_of(work, struct memory_failure_cpu, work);
- for (;;) {
- spin_lock_irqsave(&mf_cpu->lock, proc_flags);
- gotten = kfifo_get(&mf_cpu->fifo, &entry);
- spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
- if (!gotten)
- break;
- if (entry.flags & MF_SOFT_OFFLINE)
- soft_offline_page(entry.pfn, entry.flags);
- else
- memory_failure(entry.pfn, entry.flags);
- }
- }
- /*
- * Process memory_failure work queued on the specified CPU.
- * Used to avoid return-to-userspace racing with the memory_failure workqueue.
- */
- void memory_failure_queue_kick(int cpu)
- {
- struct memory_failure_cpu *mf_cpu;
- mf_cpu = &per_cpu(memory_failure_cpu, cpu);
- cancel_work_sync(&mf_cpu->work);
- memory_failure_work_func(&mf_cpu->work);
- }
- static int __init memory_failure_init(void)
- {
- struct memory_failure_cpu *mf_cpu;
- int cpu;
- for_each_possible_cpu(cpu) {
- mf_cpu = &per_cpu(memory_failure_cpu, cpu);
- spin_lock_init(&mf_cpu->lock);
- INIT_KFIFO(mf_cpu->fifo);
- INIT_WORK(&mf_cpu->work, memory_failure_work_func);
- }
- return 0;
- }
- core_initcall(memory_failure_init);
- #define unpoison_pr_info(fmt, pfn, rs) \
- ({ \
- if (__ratelimit(rs)) \
- pr_info(fmt, pfn); \
- })
- /**
- * unpoison_memory - Unpoison a previously poisoned page
- * @pfn: Page number of the to be unpoisoned page
- *
- * Software-unpoison a page that has been poisoned by
- * memory_failure() earlier.
- *
- * This is only done on the software-level, so it only works
- * for linux injected failures, not real hardware failures
- *
- * Returns 0 for success, otherwise -errno.
- */
- int unpoison_memory(unsigned long pfn)
- {
- struct page *page;
- struct page *p;
- int freeit = 0;
- static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
- DEFAULT_RATELIMIT_BURST);
- if (!pfn_valid(pfn))
- return -ENXIO;
- p = pfn_to_page(pfn);
- page = compound_head(p);
- if (!PageHWPoison(p)) {
- unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n",
- pfn, &unpoison_rs);
- return 0;
- }
- if (page_count(page) > 1) {
- unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n",
- pfn, &unpoison_rs);
- return 0;
- }
- if (page_mapped(page)) {
- unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n",
- pfn, &unpoison_rs);
- return 0;
- }
- if (page_mapping(page)) {
- unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n",
- pfn, &unpoison_rs);
- return 0;
- }
- /*
- * unpoison_memory() can encounter thp only when the thp is being
- * worked by memory_failure() and the page lock is not held yet.
- * In such case, we yield to memory_failure() and make unpoison fail.
- */
- if (!PageHuge(page) && PageTransHuge(page)) {
- unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n",
- pfn, &unpoison_rs);
- return 0;
- }
- if (!get_hwpoison_page(p)) {
- if (TestClearPageHWPoison(p))
- num_poisoned_pages_dec();
- unpoison_pr_info("Unpoison: Software-unpoisoned free page %#lx\n",
- pfn, &unpoison_rs);
- return 0;
- }
- lock_page(page);
- /*
- * This test is racy because PG_hwpoison is set outside of page lock.
- * That's acceptable because that won't trigger kernel panic. Instead,
- * the PG_hwpoison page will be caught and isolated on the entrance to
- * the free buddy page pool.
- */
- if (TestClearPageHWPoison(page)) {
- unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
- pfn, &unpoison_rs);
- num_poisoned_pages_dec();
- freeit = 1;
- }
- unlock_page(page);
- put_page(page);
- if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1))
- put_page(page);
- return 0;
- }
- EXPORT_SYMBOL(unpoison_memory);
- /*
- * Safely get reference count of an arbitrary page.
- * Returns 0 for a free page, -EIO for a zero refcount page
- * that is not free, and 1 for any other page type.
- * For 1 the page is returned with increased page count, otherwise not.
- */
- static int __get_any_page(struct page *p, unsigned long pfn, int flags)
- {
- int ret;
- if (flags & MF_COUNT_INCREASED)
- return 1;
- /*
- * When the target page is a free hugepage, just remove it
- * from free hugepage list.
- */
- if (!get_hwpoison_page(p)) {
- if (PageHuge(p)) {
- pr_info("%s: %#lx free huge page\n", __func__, pfn);
- ret = 0;
- } else if (is_free_buddy_page(p)) {
- pr_info("%s: %#lx free buddy page\n", __func__, pfn);
- ret = 0;
- } else if (page_count(p)) {
- /* raced with allocation */
- ret = -EBUSY;
- } else {
- pr_info("%s: %#lx: unknown zero refcount page type %lx\n",
- __func__, pfn, p->flags);
- ret = -EIO;
- }
- } else {
- /* Not a free page */
- ret = 1;
- }
- return ret;
- }
- static int get_any_page(struct page *page, unsigned long pfn, int flags)
- {
- int ret = __get_any_page(page, pfn, flags);
- if (ret == -EBUSY)
- ret = __get_any_page(page, pfn, flags);
- if (ret == 1 && !PageHuge(page) &&
- !PageLRU(page) && !__PageMovable(page)) {
- /*
- * Try to free it.
- */
- put_page(page);
- shake_page(page, 1);
- /*
- * Did it turn free?
- */
- ret = __get_any_page(page, pfn, 0);
- if (ret == 1 && !PageLRU(page)) {
- /* Drop page reference which is from __get_any_page() */
- put_page(page);
- pr_info("soft_offline: %#lx: unknown non LRU page type %lx (%pGp)\n",
- pfn, page->flags, &page->flags);
- return -EIO;
- }
- }
- return ret;
- }
- static bool isolate_page(struct page *page, struct list_head *pagelist)
- {
- bool isolated = false;
- bool lru = PageLRU(page);
- if (PageHuge(page)) {
- isolated = isolate_huge_page(page, pagelist);
- } else {
- if (lru)
- isolated = !isolate_lru_page(page);
- else
- isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
- if (isolated)
- list_add(&page->lru, pagelist);
- }
- if (isolated && lru)
- inc_node_page_state(page, NR_ISOLATED_ANON +
- page_is_file_lru(page));
- /*
- * If we succeed to isolate the page, we grabbed another refcount on
- * the page, so we can safely drop the one we got from get_any_pages().
- * If we failed to isolate the page, it means that we cannot go further
- * and we will return an error, so drop the reference we got from
- * get_any_pages() as well.
- */
- put_page(page);
- return isolated;
- }
- /*
- * __soft_offline_page handles hugetlb-pages and non-hugetlb pages.
- * If the page is a non-dirty unmapped page-cache page, it simply invalidates.
- * If the page is mapped, it migrates the contents over.
- */
- static int __soft_offline_page(struct page *page)
- {
- int ret = 0;
- unsigned long pfn = page_to_pfn(page);
- struct page *hpage = compound_head(page);
- char const *msg_page[] = {"page", "hugepage"};
- bool huge = PageHuge(page);
- LIST_HEAD(pagelist);
- struct migration_target_control mtc = {
- .nid = NUMA_NO_NODE,
- .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
- };
- /*
- * Check PageHWPoison again inside page lock because PageHWPoison
- * is set by memory_failure() outside page lock. Note that
- * memory_failure() also double-checks PageHWPoison inside page lock,
- * so there's no race between soft_offline_page() and memory_failure().
- */
- lock_page(page);
- if (!PageHuge(page))
- wait_on_page_writeback(page);
- if (PageHWPoison(page)) {
- unlock_page(page);
- put_page(page);
- pr_info("soft offline: %#lx page already poisoned\n", pfn);
- return 0;
- }
- if (!PageHuge(page))
- /*
- * Try to invalidate first. This should work for
- * non dirty unmapped page cache pages.
- */
- ret = invalidate_inode_page(page);
- unlock_page(page);
- /*
- * RED-PEN would be better to keep it isolated here, but we
- * would need to fix isolation locking first.
- */
- if (ret) {
- pr_info("soft_offline: %#lx: invalidated\n", pfn);
- page_handle_poison(page, false, true);
- return 0;
- }
- if (isolate_page(hpage, &pagelist)) {
- ret = migrate_pages(&pagelist, alloc_migration_target, NULL,
- (unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_FAILURE);
- if (!ret) {
- bool release = !huge;
- if (!page_handle_poison(page, huge, release))
- ret = -EBUSY;
- } else {
- if (!list_empty(&pagelist))
- putback_movable_pages(&pagelist);
- pr_info("soft offline: %#lx: %s migration failed %d, type %lx (%pGp)\n",
- pfn, msg_page[huge], ret, page->flags, &page->flags);
- if (ret > 0)
- ret = -EBUSY;
- }
- } else {
- pr_info("soft offline: %#lx: %s isolation failed, page count %d, type %lx (%pGp)\n",
- pfn, msg_page[huge], page_count(page), page->flags, &page->flags);
- ret = -EBUSY;
- }
- return ret;
- }
- static int soft_offline_in_use_page(struct page *page)
- {
- struct page *hpage = compound_head(page);
- if (!PageHuge(page) && PageTransHuge(hpage))
- if (try_to_split_thp_page(page, "soft offline") < 0)
- return -EBUSY;
- return __soft_offline_page(page);
- }
- static int soft_offline_free_page(struct page *page)
- {
- int rc = 0;
- if (!page_handle_poison(page, true, false))
- rc = -EBUSY;
- return rc;
- }
- /**
- * soft_offline_page - Soft offline a page.
- * @pfn: pfn to soft-offline
- * @flags: flags. Same as memory_failure().
- *
- * Returns 0 on success, otherwise negated errno.
- *
- * Soft offline a page, by migration or invalidation,
- * without killing anything. This is for the case when
- * a page is not corrupted yet (so it's still valid to access),
- * but has had a number of corrected errors and is better taken
- * out.
- *
- * The actual policy on when to do that is maintained by
- * user space.
- *
- * This should never impact any application or cause data loss,
- * however it might take some time.
- *
- * This is not a 100% solution for all memory, but tries to be
- * ``good enough'' for the majority of memory.
- */
- int soft_offline_page(unsigned long pfn, int flags)
- {
- int ret;
- struct page *page;
- bool try_again = true;
- if (!pfn_valid(pfn))
- return -ENXIO;
- /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
- page = pfn_to_online_page(pfn);
- if (!page)
- return -EIO;
- if (PageHWPoison(page)) {
- pr_info("soft offline: %#lx page already poisoned\n", pfn);
- if (flags & MF_COUNT_INCREASED)
- put_page(page);
- return 0;
- }
- retry:
- get_online_mems();
- ret = get_any_page(page, pfn, flags);
- put_online_mems();
- if (ret > 0)
- ret = soft_offline_in_use_page(page);
- else if (ret == 0)
- if (soft_offline_free_page(page) && try_again) {
- try_again = false;
- flags &= ~MF_COUNT_INCREASED;
- goto retry;
- }
- return ret;
- }
|