diff options
Diffstat (limited to 'mm/memory-failure.c')
| -rw-r--r-- | mm/memory-failure.c | 560 |
1 files changed, 506 insertions, 54 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 50d4f8d7024..6a0466ed5bf 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -34,12 +34,16 @@ #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/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 "internal.h" int sysctl_memory_failure_early_kill __read_mostly = 0; @@ -48,6 +52,120 @@ int sysctl_memory_failure_recovery __read_mostly = 1; atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0); +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 page + */ + 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_CGROUP_MEM_RES_CTLR_SWAP +u64 hwpoison_filter_memcg; +EXPORT_SYMBOL_GPL(hwpoison_filter_memcg); +static int hwpoison_filter_task(struct page *p) +{ + struct mem_cgroup *mem; + struct cgroup_subsys_state *css; + unsigned long ino; + + if (!hwpoison_filter_memcg) + return 0; + + mem = try_get_mem_cgroup_from_page(p); + if (!mem) + return -EINVAL; + + css = mem_cgroup_css(mem); + /* root_mem_cgroup has NULL dentries */ + if (!css->cgroup->dentry) + return -EINVAL; + + ino = css->cgroup->dentry->d_inode->i_ino; + css_put(css); + + if (ino != 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; +} +EXPORT_SYMBOL_GPL(hwpoison_filter); + /* * Send all the processes who have the page mapped an ``action optional'' * signal. @@ -83,6 +201,36 @@ static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno, } /* + * 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(); + if (PageLRU(p) || is_free_buddy_page(p)) + return; + } + + /* + * Only all shrink_slab here (which would also + * shrink other caches) if access is not potentially fatal. + */ + if (access) { + int nr; + do { + nr = shrink_slab(1000, GFP_KERNEL, 1000); + if (page_count(p) == 0) + break; + } while (nr > 10); + } +} +EXPORT_SYMBOL_GPL(shake_page); + +/* * Kill all processes that have a poisoned page mapped and then isolate * the page. * @@ -177,7 +325,6 @@ static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno, * In case something went wrong with munmapping * make sure the process doesn't catch the * signal and then access the memory. Just kill it. - * the signal handlers */ if (fail || tk->addr_valid == 0) { printk(KERN_ERR @@ -314,33 +461,49 @@ static void collect_procs(struct page *page, struct list_head *tokill) */ enum outcome { - FAILED, /* Error handling failed */ + IGNORED, /* Error: cannot be handled */ + FAILED, /* Error: handling failed */ DELAYED, /* Will be handled later */ - IGNORED, /* Error safely ignored */ RECOVERED, /* Successfully recovered */ }; static const char *action_name[] = { + [IGNORED] = "Ignored", [FAILED] = "Failed", [DELAYED] = "Delayed", - [IGNORED] = "Ignored", [RECOVERED] = "Recovered", }; /* - * Error hit kernel page. - * Do nothing, try to be lucky and not touch this instead. For a few cases we - * could be more sophisticated. + * 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 me_kernel(struct page *p, unsigned long pfn) +static int delete_from_lru_cache(struct page *p) { - return DELAYED; + 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() + */ + page_cache_release(p); + return 0; + } + return -EIO; } /* - * Already poisoned page. + * 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_ignore(struct page *p, unsigned long pfn) +static int me_kernel(struct page *p, unsigned long pfn) { return IGNORED; } @@ -355,14 +518,6 @@ static int me_unknown(struct page *p, unsigned long pfn) } /* - * Free memory - */ -static int me_free(struct page *p, unsigned long pfn) -{ - return DELAYED; -} - -/* * Clean (or cleaned) page cache page. */ static int me_pagecache_clean(struct page *p, unsigned long pfn) @@ -371,6 +526,8 @@ static int me_pagecache_clean(struct page *p, unsigned long pfn) int ret = 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. @@ -500,14 +657,20 @@ static int me_swapcache_dirty(struct page *p, unsigned long pfn) /* Trigger EIO in shmem: */ ClearPageUptodate(p); - return DELAYED; + if (!delete_from_lru_cache(p)) + return DELAYED; + else + return FAILED; } static int me_swapcache_clean(struct page *p, unsigned long pfn) { delete_from_swap_cache(p); - return RECOVERED; + if (!delete_from_lru_cache(p)) + return RECOVERED; + else + return FAILED; } /* @@ -550,7 +713,6 @@ static int me_huge_page(struct page *p, unsigned long pfn) #define tail (1UL << PG_tail) #define compound (1UL << PG_compound) #define slab (1UL << PG_slab) -#define buddy (1UL << PG_buddy) #define reserved (1UL << PG_reserved) static struct page_state { @@ -559,8 +721,11 @@ static struct page_state { char *msg; int (*action)(struct page *p, unsigned long pfn); } error_states[] = { - { reserved, reserved, "reserved kernel", me_ignore }, - { buddy, buddy, "free kernel", me_free }, + { reserved, reserved, "reserved 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 @@ -587,7 +752,6 @@ static struct page_state { { lru|dirty, lru|dirty, "LRU", me_pagecache_dirty }, { lru|dirty, lru, "clean LRU", me_pagecache_clean }, - { swapbacked, swapbacked, "anonymous", me_pagecache_clean }, /* * Catchall entry: must be at end. @@ -595,20 +759,31 @@ static struct page_state { { 0, 0, "unknown page state", me_unknown }, }; +#undef dirty +#undef sc +#undef unevict +#undef mlock +#undef writeback +#undef lru +#undef swapbacked +#undef head +#undef tail +#undef compound +#undef slab +#undef reserved + static void action_result(unsigned long pfn, char *msg, int result) { - struct page *page = NULL; - if (pfn_valid(pfn)) - page = pfn_to_page(pfn); + struct page *page = pfn_to_page(pfn); printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n", pfn, - page && PageDirty(page) ? "dirty " : "", + PageDirty(page) ? "dirty " : "", msg, action_name[result]); } static int page_action(struct page_state *ps, struct page *p, - unsigned long pfn, int ref) + unsigned long pfn) { int result; int count; @@ -616,18 +791,22 @@ static int page_action(struct page_state *ps, struct page *p, result = ps->action(p, pfn); action_result(pfn, ps->msg, result); - count = page_count(p) - 1 - ref; - if (count != 0) + count = page_count(p) - 1; + if (ps->action == me_swapcache_dirty && result == DELAYED) + count--; + if (count != 0) { printk(KERN_ERR "MCE %#lx: %s page still referenced by %d users\n", pfn, ps->msg, count); + result = FAILED; + } /* Could do more checks here if page looks ok */ /* * Could adjust zone counters here to correct for the missing page. */ - return result == RECOVERED ? 0 : -EBUSY; + return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY; } #define N_UNMAP_TRIES 5 @@ -636,7 +815,7 @@ static int page_action(struct page_state *ps, struct page *p, * 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 void hwpoison_user_mappings(struct page *p, unsigned long pfn, +static int hwpoison_user_mappings(struct page *p, unsigned long pfn, int trapno) { enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS; @@ -646,15 +825,18 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn, int i; int kill = 1; - if (PageReserved(p) || PageCompound(p) || PageSlab(p) || PageKsm(p)) - return; + if (PageReserved(p) || PageSlab(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(p)) - return; + return SWAP_SUCCESS; + + if (PageCompound(p) || PageKsm(p)) + return SWAP_FAIL; if (PageSwapCache(p)) { printk(KERN_ERR @@ -665,6 +847,8 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn, /* * 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(p); if (!PageDirty(p) && mapping && mapping_cap_writeback_dirty(mapping)) { @@ -716,11 +900,12 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn, */ kill_procs_ao(&tokill, !!PageDirty(p), trapno, ret != SWAP_SUCCESS, pfn); + + return ret; } -int __memory_failure(unsigned long pfn, int trapno, int ref) +int __memory_failure(unsigned long pfn, int trapno, int flags) { - unsigned long lru_flag; struct page_state *ps; struct page *p; int res; @@ -729,13 +914,15 @@ int __memory_failure(unsigned long pfn, int trapno, int ref) panic("Memory failure from trap %d on page %lx", trapno, pfn); if (!pfn_valid(pfn)) { - action_result(pfn, "memory outside kernel control", IGNORED); - return -EIO; + printk(KERN_ERR + "MCE %#lx: memory outside kernel control\n", + pfn); + return -ENXIO; } p = pfn_to_page(pfn); if (TestSetPageHWPoison(p)) { - action_result(pfn, "already hardware poisoned", IGNORED); + printk(KERN_ERR "MCE %#lx: already hardware poisoned\n", pfn); return 0; } @@ -752,9 +939,15 @@ int __memory_failure(unsigned long pfn, int trapno, int ref) * In fact it's dangerous to directly bump up page count from 0, * that may make page_freeze_refs()/page_unfreeze_refs() mismatch. */ - if (!get_page_unless_zero(compound_head(p))) { - action_result(pfn, "free or high order kernel", IGNORED); - return PageBuddy(compound_head(p)) ? 0 : -EBUSY; + if (!(flags & MF_COUNT_INCREASED) && + !get_page_unless_zero(compound_head(p))) { + if (is_free_buddy_page(p)) { + action_result(pfn, "free buddy", DELAYED); + return 0; + } else { + action_result(pfn, "high order kernel", IGNORED); + return -EBUSY; + } } /* @@ -766,14 +959,19 @@ int __memory_failure(unsigned long pfn, int trapno, int ref) * walked by the page reclaim code, however that's not a big loss. */ if (!PageLRU(p)) - lru_add_drain_all(); - lru_flag = p->flags & lru; - if (isolate_lru_page(p)) { + shake_page(p, 0); + if (!PageLRU(p)) { + /* + * shake_page could have turned it free. + */ + if (is_free_buddy_page(p)) { + action_result(pfn, "free buddy, 2nd try", DELAYED); + return 0; + } action_result(pfn, "non LRU", IGNORED); put_page(p); return -EBUSY; } - page_cache_release(p); /* * Lock the page and wait for writeback to finish. @@ -781,26 +979,48 @@ int __memory_failure(unsigned long pfn, int trapno, int ref) * and in many cases impossible, so we just avoid it here. */ lock_page_nosync(p); + + /* + * unpoison always clear PG_hwpoison inside page lock + */ + if (!PageHWPoison(p)) { + printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn); + res = 0; + goto out; + } + if (hwpoison_filter(p)) { + if (TestClearPageHWPoison(p)) + atomic_long_dec(&mce_bad_pages); + unlock_page(p); + put_page(p); + return 0; + } + wait_on_page_writeback(p); /* * Now take care of user space mappings. + * Abort on fail: __remove_from_page_cache() assumes unmapped page. */ - hwpoison_user_mappings(p, pfn, trapno); + if (hwpoison_user_mappings(p, pfn, trapno) != SWAP_SUCCESS) { + printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn); + res = -EBUSY; + goto out; + } /* * Torn down by someone else? */ - if ((lru_flag & lru) && !PageSwapCache(p) && p->mapping == NULL) { + if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) { action_result(pfn, "already truncated LRU", IGNORED); - res = 0; + res = -EBUSY; goto out; } res = -EBUSY; for (ps = error_states;; ps++) { - if (((p->flags | lru_flag)& ps->mask) == ps->res) { - res = page_action(ps, p, pfn, ref); + if ((p->flags & ps->mask) == ps->res) { + res = page_action(ps, p, pfn); break; } } @@ -831,3 +1051,235 @@ void memory_failure(unsigned long pfn, int trapno) { __memory_failure(pfn, trapno, 0); } + +/** + * 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; + + if (!pfn_valid(pfn)) + return -ENXIO; + + p = pfn_to_page(pfn); + page = compound_head(p); + + if (!PageHWPoison(p)) { + pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn); + return 0; + } + + if (!get_page_unless_zero(page)) { + if (TestClearPageHWPoison(p)) + atomic_long_dec(&mce_bad_pages); + pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn); + return 0; + } + + lock_page_nosync(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(p)) { + pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn); + atomic_long_dec(&mce_bad_pages); + freeit = 1; + } + unlock_page(page); + + put_page(page); + if (freeit) + put_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); + return alloc_pages_exact_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; + + /* + * The lock_system_sleep prevents a race with memory hotplug, + * because the isolation assumes there's only a single user. + * This is a big hammer, a better would be nicer. + */ + lock_system_sleep(); + + /* + * Isolate the page, so that it doesn't get reallocated if it + * was free. + */ + set_migratetype_isolate(p); + if (!get_page_unless_zero(compound_head(p))) { + if (is_free_buddy_page(p)) { + pr_debug("get_any_page: %#lx free buddy page\n", pfn); + /* Set hwpoison bit while page is still isolated */ + SetPageHWPoison(p); + ret = 0; + } else { + pr_debug("get_any_page: %#lx: unknown zero refcount page type %lx\n", + pfn, p->flags); + ret = -EIO; + } + } else { + /* Not a free page */ + ret = 1; + } + unset_migratetype_isolate(p); + unlock_system_sleep(); + return ret; +} + +/** + * 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); + + ret = get_any_page(page, pfn, flags); + if (ret < 0) + return ret; + if (ret == 0) + goto done; + + /* + * Page cache page we can handle? + */ + if (!PageLRU(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 < 0) + return ret; + if (ret == 0) + goto done; + } + if (!PageLRU(page)) { + pr_debug("soft_offline: %#lx: unknown non LRU page type %lx\n", + pfn, page->flags); + return -EIO; + } + + lock_page(page); + wait_on_page_writeback(page); + + /* + * Synchronized using the page lock with memory_failure() + */ + if (PageHWPoison(page)) { + unlock_page(page); + put_page(page); + pr_debug("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); + + /* + * Drop count because page migration doesn't like raised + * counts. The page could get re-allocated, but if it becomes + * LRU the isolation will just fail. + * RED-PEN would be better to keep it isolated here, but we + * would need to fix isolation locking first. + */ + put_page(page); + if (ret == 1) { + ret = 0; + pr_debug("soft_offline: %#lx: invalidated\n", pfn); + goto done; + } + + /* + * 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); + if (!ret) { + LIST_HEAD(pagelist); + + list_add(&page->lru, &pagelist); + ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0); + if (ret) { + pr_debug("soft offline: %#lx: migration failed %d, type %lx\n", + pfn, ret, page->flags); + if (ret > 0) + ret = -EIO; + } + } else { + pr_debug("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", + pfn, ret, page_count(page), page->flags); + } + if (ret) + return ret; + +done: + atomic_long_add(1, &mce_bad_pages); + SetPageHWPoison(page); + /* keep elevated page count for bad page */ + return ret; +} |