| /* |
| * Copyright (C) 2008, 2009 Intel Corporation |
| * Authors: Andi Kleen, Fengguang Wu |
| * |
| * This software may be redistributed and/or modified under the terms of |
| * the GNU General Public License ("GPL") version 2 only as published by the |
| * Free Software Foundation. |
| * |
| * 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.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/page-isolation.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/kfifo.h> |
| #include <linux/ratelimit.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); |
| |
| #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); |
| |
| /* |
| * 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 task_struct *t, unsigned long addr, int trapno, |
| unsigned long pfn, struct page *page, int flags) |
| { |
| struct siginfo si; |
| int ret; |
| |
| pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corruption\n", |
| pfn, t->comm, t->pid); |
| si.si_signo = SIGBUS; |
| si.si_errno = 0; |
| si.si_addr = (void *)addr; |
| #ifdef __ARCH_SI_TRAPNO |
| si.si_trapno = trapno; |
| #endif |
| si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT; |
| |
| if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) { |
| si.si_code = BUS_MCEERR_AR; |
| ret = force_sig_info(SIGBUS, &si, current); |
| } 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? |
| */ |
| si.si_code = BUS_MCEERR_AO; |
| ret = send_sig_info(SIGBUS, &si, 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 (!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); |
| |
| /* |
| * 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; |
| char addr_valid; |
| }; |
| |
| /* |
| * 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. |
| * TBD would GFP_NOIO be enough? |
| */ |
| 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 **tkc) |
| { |
| struct to_kill *tk; |
| |
| if (*tkc) { |
| tk = *tkc; |
| *tkc = NULL; |
| } else { |
| 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); |
| tk->addr_valid = 1; |
| |
| /* |
| * In theory we don't have to kill when the page was |
| * munmaped. But it could be also a mremap. Since that's |
| * likely very rare kill anyways just out of paranoia, but use |
| * a SIGKILL because the error is not contained anymore. |
| */ |
| if (tk->addr == -EFAULT) { |
| pr_info("Memory failure: Unable to find user space address %lx in %s\n", |
| page_to_pfn(p), tsk->comm); |
| tk->addr_valid = 0; |
| } |
| 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, int trapno, |
| int fail, struct page *page, 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_valid == 0) { |
| pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", |
| pfn, tk->tsk->comm, tk->tsk->pid); |
| force_sig(SIGKILL, tk->tsk); |
| } |
| |
| /* |
| * 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->tsk, tk->addr, trapno, |
| pfn, page, 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) && (t->flags & PF_MCE_EARLY)) |
| 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. |
| */ |
| static struct task_struct *task_early_kill(struct task_struct *tsk, |
| int force_early) |
| { |
| struct task_struct *t; |
| if (!tsk->mm) |
| return NULL; |
| if (force_early) |
| return tsk; |
| t = find_early_kill_thread(tsk); |
| if (t) |
| return t; |
| if (sysctl_memory_failure_early_kill) |
| return tsk; |
| return NULL; |
| } |
| |
| /* |
| * Collect processes when the error hit an anonymous page. |
| */ |
| static void collect_procs_anon(struct page *page, struct list_head *to_kill, |
| struct to_kill **tkc, 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, tkc); |
| } |
| } |
| 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, |
| struct to_kill **tkc, int force_early) |
| { |
| struct vm_area_struct *vma; |
| struct task_struct *tsk; |
| struct address_space *mapping = page->mapping; |
| |
| i_mmap_lock_read(mapping); |
| read_lock(&tasklist_lock); |
| for_each_process(tsk) { |
| pgoff_t pgoff = page_to_pgoff(page); |
| 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, tkc); |
| } |
| } |
| read_unlock(&tasklist_lock); |
| i_mmap_unlock_read(mapping); |
| } |
| |
| /* |
| * Collect the processes who have the corrupted page mapped to kill. |
| * This is done in two steps for locking reasons. |
| * First preallocate one tokill structure outside the spin locks, |
| * so that we can kill at least one process reasonably reliable. |
| */ |
| static void collect_procs(struct page *page, struct list_head *tokill, |
| int force_early) |
| { |
| struct to_kill *tk; |
| |
| if (!page->mapping) |
| return; |
| |
| tk = kmalloc(sizeof(struct to_kill), GFP_NOIO); |
| if (!tk) |
| return; |
| if (PageAnon(page)) |
| collect_procs_anon(page, tokill, &tk, force_early); |
| else |
| collect_procs_file(page, tokill, &tk, force_early); |
| kfree(tk); |
| } |
| |
| 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_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_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); |
| /* |
| * drop the page count elevated by isolate_lru_page() |
| */ |
| put_page(p); |
| return 0; |
| } |
| return -EIO; |
| } |
| |
| /* |
| * 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) |
| { |
| int err; |
| int ret = MF_FAILED; |
| 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. |
| */ |
| if (mapping->a_ops->error_remove_page) { |
| 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; |
| } |
| |
| /* |
| * 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); |
| |
| if (!PageHuge(hpage)) |
| return MF_DELAYED; |
| |
| /* |
| * We can safely recover from error on free or reserved (i.e. |
| * not in-use) hugepage by dequeuing it from freelist. |
| * To check whether a hugepage is in-use or not, we can't use |
| * page->lru because it can be used in other hugepage operations, |
| * such as __unmap_hugepage_range() and gather_surplus_pages(). |
| * So instead we use page_mapping() and PageAnon(). |
| */ |
| if (!(page_mapping(hpage) || PageAnon(hpage))) { |
| res = dequeue_hwpoisoned_huge_page(hpage); |
| if (!res) |
| return MF_RECOVERED; |
| } |
| return MF_DELAYED; |
| } |
| |
| /* |
| * 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) |
| #define unevict (1UL << PG_unevictable) |
| #define mlock (1UL << PG_mlocked) |
| #define writeback (1UL << PG_writeback) |
| #define lru (1UL << PG_lru) |
| #define swapbacked (1UL << PG_swapbacked) |
| #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 writeback |
| #undef lru |
| #undef swapbacked |
| #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.) |
| */ |
| 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; |
| } |
| EXPORT_SYMBOL_GPL(get_hwpoison_page); |
| |
| /* |
| * 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 int hwpoison_user_mappings(struct page *p, unsigned long pfn, |
| int trapno, int flags, struct page **hpagep) |
| { |
| enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; |
| struct address_space *mapping; |
| LIST_HEAD(tokill); |
| int ret; |
| int kill = 1, forcekill; |
| struct page *hpage = *hpagep; |
| |
| /* |
| * Here we are interested only in user-mapped pages, so skip any |
| * other types of pages. |
| */ |
| if (PageReserved(p) || PageSlab(p)) |
| return SWAP_SUCCESS; |
| if (!(PageLRU(hpage) || PageHuge(p))) |
| return SWAP_SUCCESS; |
| |
| /* |
| * 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 SWAP_SUCCESS; |
| |
| if (PageKsm(p)) { |
| pr_err("Memory failure: %#lx: can't handle KSM pages.\n", pfn); |
| return SWAP_FAIL; |
| } |
| |
| 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_cap_writeback_dirty(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); |
| |
| ret = try_to_unmap(hpage, ttu); |
| if (ret != SWAP_SUCCESS) |
| pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n", |
| pfn, page_mapcount(hpage)); |
| |
| /* |
| * 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, trapno, |
| ret != SWAP_SUCCESS, p, pfn, flags); |
| |
| return ret; |
| } |
| |
| static void set_page_hwpoison_huge_page(struct page *hpage) |
| { |
| int i; |
| int nr_pages = 1 << compound_order(hpage); |
| for (i = 0; i < nr_pages; i++) |
| SetPageHWPoison(hpage + i); |
| } |
| |
| static void clear_page_hwpoison_huge_page(struct page *hpage) |
| { |
| int i; |
| int nr_pages = 1 << compound_order(hpage); |
| for (i = 0; i < nr_pages; i++) |
| ClearPageHWPoison(hpage + i); |
| } |
| |
| /** |
| * memory_failure - Handle memory failure of a page. |
| * @pfn: Page Number of the corrupted page |
| * @trapno: Trap number reported in the signal to user space. |
| * @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 trapno, int flags) |
| { |
| struct page_state *ps; |
| struct page *p; |
| struct page *hpage; |
| struct page *orig_head; |
| int res; |
| unsigned int nr_pages; |
| unsigned long page_flags; |
| |
| if (!sysctl_memory_failure_recovery) |
| panic("Memory failure from trap %d on page %lx", trapno, pfn); |
| |
| if (!pfn_valid(pfn)) { |
| pr_err("Memory failure: %#lx: memory outside kernel control\n", |
| pfn); |
| return -ENXIO; |
| } |
| |
| p = pfn_to_page(pfn); |
| orig_head = hpage = compound_head(p); |
| if (TestSetPageHWPoison(p)) { |
| pr_err("Memory failure: %#lx: already hardware poisoned\n", |
| pfn); |
| return 0; |
| } |
| |
| /* |
| * Currently errors on hugetlbfs pages are measured in hugepage units, |
| * so nr_pages should be 1 << compound_order. OTOH when errors are on |
| * transparent hugepages, they are supposed to be split and error |
| * measurement is done in normal page units. So nr_pages should be one |
| * in this case. |
| */ |
| if (PageHuge(p)) |
| nr_pages = 1 << compound_order(hpage); |
| else /* normal page or thp */ |
| nr_pages = 1; |
| num_poisoned_pages_add(nr_pages); |
| |
| /* |
| * 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 a free hugepage, which is also safe: |
| * an affected hugepage will be dequeued from hugepage freelist, |
| * so there's no concern about reusing it ever after. |
| * 3) 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_freeze_refs()/page_unfreeze_refs() 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 if (PageHuge(hpage)) { |
| /* |
| * Check "filter hit" and "race with other subpage." |
| */ |
| lock_page(hpage); |
| if (PageHWPoison(hpage)) { |
| if ((hwpoison_filter(p) && TestClearPageHWPoison(p)) |
| || (p != hpage && TestSetPageHWPoison(hpage))) { |
| num_poisoned_pages_sub(nr_pages); |
| unlock_page(hpage); |
| return 0; |
| } |
| } |
| set_page_hwpoison_huge_page(hpage); |
| res = dequeue_hwpoisoned_huge_page(hpage); |
| action_result(pfn, MF_MSG_FREE_HUGE, |
| res ? MF_IGNORED : MF_DELAYED); |
| unlock_page(hpage); |
| return res; |
| } else { |
| action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED); |
| return -EBUSY; |
| } |
| } |
| |
| if (!PageHuge(p) && PageTransHuge(hpage)) { |
| lock_page(p); |
| if (!PageAnon(p) || unlikely(split_huge_page(p))) { |
| unlock_page(p); |
| if (!PageAnon(p)) |
| pr_err("Memory failure: %#lx: non anonymous thp\n", |
| pfn); |
| else |
| pr_err("Memory failure: %#lx: thp split failed\n", |
| pfn); |
| if (TestClearPageHWPoison(p)) |
| num_poisoned_pages_sub(nr_pages); |
| put_hwpoison_page(p); |
| return -EBUSY; |
| } |
| unlock_page(p); |
| VM_BUG_ON_PAGE(!page_count(p), p); |
| hpage = compound_head(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. |
| */ |
| if (!PageHuge(p)) { |
| if (!PageLRU(p)) |
| shake_page(p, 0); |
| if (!PageLRU(p)) { |
| /* |
| * shake_page could have turned it free. |
| */ |
| if (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(hpage); |
| |
| /* |
| * 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_sub(nr_pages); |
| unlock_page(hpage); |
| put_hwpoison_page(hpage); |
| return 0; |
| } |
| if (hwpoison_filter(p)) { |
| if (TestClearPageHWPoison(p)) |
| num_poisoned_pages_sub(nr_pages); |
| unlock_page(hpage); |
| put_hwpoison_page(hpage); |
| return 0; |
| } |
| |
| if (!PageHuge(p) && !PageTransTail(p) && !PageLRU(p)) |
| goto identify_page_state; |
| |
| /* |
| * For error on the tail page, we should set PG_hwpoison |
| * on the head page to show that the hugepage is hwpoisoned |
| */ |
| if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) { |
| action_result(pfn, MF_MSG_POISONED_HUGE, MF_IGNORED); |
| unlock_page(hpage); |
| put_hwpoison_page(hpage); |
| return 0; |
| } |
| /* |
| * Set PG_hwpoison on all pages in an error hugepage, |
| * because containment is done in hugepage unit for now. |
| * Since we have done TestSetPageHWPoison() for the head page with |
| * page lock held, we can safely set PG_hwpoison bits on tail pages. |
| */ |
| if (PageHuge(p)) |
| set_page_hwpoison_huge_page(hpage); |
| |
| /* |
| * 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. |
| * |
| * When the raw error page is thp tail page, hpage points to the raw |
| * page after thp split. |
| */ |
| if (hwpoison_user_mappings(p, pfn, trapno, flags, &hpage) |
| != SWAP_SUCCESS) { |
| 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 = -EBUSY; |
| /* |
| * The first check uses the current page flags which may not have any |
| * relevant information. The second check with the saved page flagss 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; |
| res = page_action(ps, p, pfn); |
| out: |
| unlock_page(hpage); |
| 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 trapno; |
| 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 |
| * @trapno: Trap number reported in the signal to user space. |
| * @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 trapno, int flags) |
| { |
| struct memory_failure_cpu *mf_cpu; |
| unsigned long proc_flags; |
| struct memory_failure_entry entry = { |
| .pfn = pfn, |
| .trapno = trapno, |
| .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 = this_cpu_ptr(&memory_failure_cpu); |
| 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(pfn_to_page(entry.pfn), entry.flags); |
| else |
| memory_failure(entry.pfn, entry.trapno, entry.flags); |
| } |
| } |
| |
| 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; |
| unsigned int nr_pages; |
| 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; |
| } |
| |
| nr_pages = 1 << compound_order(page); |
| |
| if (!get_hwpoison_page(p)) { |
| /* |
| * Since HWPoisoned hugepage should have non-zero refcount, |
| * race between memory failure and unpoison seems to happen. |
| * In such case unpoison fails and memory failure runs |
| * to the end. |
| */ |
| if (PageHuge(page)) { |
| unpoison_pr_info("Unpoison: Memory failure is now running on free hugepage %#lx\n", |
| pfn, &unpoison_rs); |
| return 0; |
| } |
| 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_sub(nr_pages); |
| freeit = 1; |
| if (PageHuge(page)) |
| clear_page_hwpoison_huge_page(page); |
| } |
| unlock_page(page); |
| |
| put_hwpoison_page(page); |
| if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) |
| put_hwpoison_page(page); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(unpoison_memory); |
| |
| static struct page *new_page(struct page *p, unsigned long private, int **x) |
| { |
| int nid = page_to_nid(p); |
| if (PageHuge(p)) |
| return alloc_huge_page_node(page_hstate(compound_head(p)), |
| nid); |
| else |
| return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0); |
| } |
| |
| /* |
| * 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 { |
| 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 == 1 && !PageHuge(page) && !PageLRU(page)) { |
| /* |
| * Try to free it. |
| */ |
| put_hwpoison_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_hwpoison_page(page); |
| pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", |
| pfn, page->flags); |
| return -EIO; |
| } |
| } |
| return ret; |
| } |
| |
| static int soft_offline_huge_page(struct page *page, int flags) |
| { |
| int ret; |
| unsigned long pfn = page_to_pfn(page); |
| struct page *hpage = compound_head(page); |
| LIST_HEAD(pagelist); |
| |
| /* |
| * This double-check of PageHWPoison is to avoid the race with |
| * memory_failure(). See also comment in __soft_offline_page(). |
| */ |
| lock_page(hpage); |
| if (PageHWPoison(hpage)) { |
| unlock_page(hpage); |
| put_hwpoison_page(hpage); |
| pr_info("soft offline: %#lx hugepage already poisoned\n", pfn); |
| return -EBUSY; |
| } |
| unlock_page(hpage); |
| |
| ret = isolate_huge_page(hpage, &pagelist); |
| /* |
| * get_any_page() and isolate_huge_page() takes a refcount each, |
| * so need to drop one here. |
| */ |
| put_hwpoison_page(hpage); |
| if (!ret) { |
| pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn); |
| return -EBUSY; |
| } |
| |
| ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, |
| MIGRATE_SYNC, MR_MEMORY_FAILURE); |
| if (ret) { |
| pr_info("soft offline: %#lx: migration failed %d, type %lx\n", |
| pfn, ret, page->flags); |
| if (!list_empty(&pagelist)) |
| putback_movable_pages(&pagelist); |
| if (ret > 0) |
| ret = -EIO; |
| } else { |
| /* overcommit hugetlb page will be freed to buddy */ |
| if (PageHuge(page)) { |
| set_page_hwpoison_huge_page(hpage); |
| dequeue_hwpoisoned_huge_page(hpage); |
| num_poisoned_pages_add(1 << compound_order(hpage)); |
| } else { |
| SetPageHWPoison(page); |
| num_poisoned_pages_inc(); |
| } |
| } |
| return ret; |
| } |
| |
| static int __soft_offline_page(struct page *page, int flags) |
| { |
| int ret; |
| unsigned long pfn = page_to_pfn(page); |
| |
| /* |
| * 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); |
| wait_on_page_writeback(page); |
| if (PageHWPoison(page)) { |
| unlock_page(page); |
| put_hwpoison_page(page); |
| pr_info("soft offline: %#lx page already poisoned\n", pfn); |
| return -EBUSY; |
| } |
| /* |
| * 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 == 1) { |
| put_hwpoison_page(page); |
| pr_info("soft_offline: %#lx: invalidated\n", pfn); |
| SetPageHWPoison(page); |
| num_poisoned_pages_inc(); |
| return 0; |
| } |
| |
| /* |
| * Simple invalidation didn't work. |
| * Try to migrate to a new page instead. migrate.c |
| * handles a large number of cases for us. |
| */ |
| ret = isolate_lru_page(page); |
| /* |
| * Drop page reference which is came from get_any_page() |
| * successful isolate_lru_page() already took another one. |
| */ |
| put_hwpoison_page(page); |
| if (!ret) { |
| LIST_HEAD(pagelist); |
| inc_node_page_state(page, NR_ISOLATED_ANON + |
| page_is_file_cache(page)); |
| list_add(&page->lru, &pagelist); |
| ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL, |
| MIGRATE_SYNC, MR_MEMORY_FAILURE); |
| if (ret) { |
| if (!list_empty(&pagelist)) { |
| list_del(&page->lru); |
| dec_node_page_state(page, NR_ISOLATED_ANON + |
| page_is_file_cache(page)); |
| putback_lru_page(page); |
| } |
| |
| pr_info("soft offline: %#lx: migration failed %d, type %lx\n", |
| pfn, ret, page->flags); |
| if (ret > 0) |
| ret = -EIO; |
| } |
| } else { |
| pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", |
| pfn, ret, page_count(page), page->flags); |
| } |
| return ret; |
| } |
| |
| static int soft_offline_in_use_page(struct page *page, int flags) |
| { |
| int ret; |
| struct page *hpage = compound_head(page); |
| |
| if (!PageHuge(page) && PageTransHuge(hpage)) { |
| lock_page(hpage); |
| if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) { |
| unlock_page(hpage); |
| if (!PageAnon(hpage)) |
| pr_info("soft offline: %#lx: non anonymous thp\n", page_to_pfn(page)); |
| else |
| pr_info("soft offline: %#lx: thp split failed\n", page_to_pfn(page)); |
| put_hwpoison_page(hpage); |
| return -EBUSY; |
| } |
| unlock_page(hpage); |
| get_hwpoison_page(page); |
| put_hwpoison_page(hpage); |
| } |
| |
| if (PageHuge(page)) |
| ret = soft_offline_huge_page(page, flags); |
| else |
| ret = __soft_offline_page(page, flags); |
| |
| return ret; |
| } |
| |
| static void soft_offline_free_page(struct page *page) |
| { |
| if (PageHuge(page)) { |
| struct page *hpage = compound_head(page); |
| |
| set_page_hwpoison_huge_page(hpage); |
| if (!dequeue_hwpoisoned_huge_page(hpage)) |
| num_poisoned_pages_add(1 << compound_order(hpage)); |
| } else { |
| if (!TestSetPageHWPoison(page)) |
| num_poisoned_pages_inc(); |
| } |
| } |
| |
| /** |
| * soft_offline_page - Soft offline a page. |
| * @page: page to 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(struct page *page, int flags) |
| { |
| int ret; |
| unsigned long pfn = page_to_pfn(page); |
| |
| if (PageHWPoison(page)) { |
| pr_info("soft offline: %#lx page already poisoned\n", pfn); |
| if (flags & MF_COUNT_INCREASED) |
| put_hwpoison_page(page); |
| return -EBUSY; |
| } |
| |
| get_online_mems(); |
| ret = get_any_page(page, pfn, flags); |
| put_online_mems(); |
| |
| if (ret > 0) |
| ret = soft_offline_in_use_page(page, flags); |
| else if (ret == 0) |
| soft_offline_free_page(page); |
| |
| return ret; |
| } |