diff options
Diffstat (limited to 'mm/memory-failure.c')
| -rw-r--r-- | mm/memory-failure.c | 176 |
1 files changed, 126 insertions, 50 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 757f6b0accfe..124324134ff6 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -7,21 +7,26 @@ * Free Software Foundation. * * High level machine check handler. Handles pages reported by the - * hardware as being corrupted usually due to a 2bit ECC memory or cache + * 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 asynchronous to other VM - * users, because memory failures could happen anytime and anywhere, - * possibly violating 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. - * - * 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 - * mappings. In short it can be quite slow. But since memory corruptions - * are rare we hope to get away with this. + * 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. + * + * 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. */ /* @@ -30,7 +35,6 @@ * - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages * - pass bad pages to kdump next kernel */ -#define DEBUG 1 /* remove me in 2.6.34 */ #include <linux/kernel.h> #include <linux/mm.h> #include <linux/page-flags.h> @@ -78,7 +82,7 @@ static int hwpoison_filter_dev(struct page *p) return 0; /* - * page_mapping() does not accept slab page + * page_mapping() does not accept slab pages. */ if (PageSlab(p)) return -EINVAL; @@ -268,7 +272,7 @@ struct to_kill { struct list_head nd; struct task_struct *tsk; unsigned long addr; - unsigned addr_valid:1; + char addr_valid; }; /* @@ -309,7 +313,7 @@ static void add_to_kill(struct task_struct *tsk, struct page *p, * a SIGKILL because the error is not contained anymore. */ if (tk->addr == -EFAULT) { - pr_debug("MCE: Unable to find user space address %lx in %s\n", + pr_info("MCE: Unable to find user space address %lx in %s\n", page_to_pfn(p), tsk->comm); tk->addr_valid = 0; } @@ -577,7 +581,7 @@ static int me_pagecache_clean(struct page *p, unsigned long pfn) pfn, err); } else if (page_has_private(p) && !try_to_release_page(p, GFP_NOIO)) { - pr_debug("MCE %#lx: failed to release buffers\n", pfn); + pr_info("MCE %#lx: failed to release buffers\n", pfn); } else { ret = RECOVERED; } @@ -693,11 +697,10 @@ static int me_swapcache_clean(struct page *p, unsigned long pfn) * 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. - * - To support soft-offlining for hugepage, we need to support hugepage - * migration. */ static int me_huge_page(struct page *p, unsigned long pfn) { + int res = 0; struct page *hpage = compound_head(p); /* * We can safely recover from error on free or reserved (i.e. @@ -710,8 +713,9 @@ static int me_huge_page(struct page *p, unsigned long pfn) * so there is no race between isolation and mapping/unmapping. */ if (!(page_mapping(hpage) || PageAnon(hpage))) { - __isolate_hwpoisoned_huge_page(hpage); - return RECOVERED; + res = dequeue_hwpoisoned_huge_page(hpage); + if (!res) + return RECOVERED; } return DELAYED; } @@ -836,8 +840,6 @@ static int page_action(struct page_state *ps, struct page *p, return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY; } -#define N_UNMAP_TRIES 5 - /* * Do all that is necessary to remove user space mappings. Unmap * the pages and send SIGBUS to the processes if the data was dirty. @@ -849,7 +851,6 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn, struct address_space *mapping; LIST_HEAD(tokill); int ret; - int i; int kill = 1; struct page *hpage = compound_head(p); @@ -903,17 +904,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn, if (kill) collect_procs(hpage, &tokill); - /* - * try_to_unmap can fail temporarily due to races. - * Try a few times (RED-PEN better strategy?) - */ - for (i = 0; i < N_UNMAP_TRIES; i++) { - ret = try_to_unmap(hpage, ttu); - if (ret == SWAP_SUCCESS) - break; - pr_debug("MCE %#lx: try_to_unmap retry needed %d\n", pfn, ret); - } - + ret = try_to_unmap(hpage, ttu); if (ret != SWAP_SUCCESS) printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n", pfn, page_mapcount(hpage)); @@ -981,7 +972,10 @@ int __memory_failure(unsigned long pfn, int trapno, int flags) * 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. + * 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. @@ -993,6 +987,24 @@ int __memory_failure(unsigned long pfn, int trapno, int flags) if (is_free_buddy_page(p)) { action_result(pfn, "free buddy", DELAYED); return 0; + } else if (PageHuge(hpage)) { + /* + * Check "just unpoisoned", "filter hit", and + * "race with other subpage." + */ + lock_page_nosync(hpage); + if (!PageHWPoison(hpage) + || (hwpoison_filter(p) && TestClearPageHWPoison(p)) + || (p != hpage && TestSetPageHWPoison(hpage))) { + atomic_long_sub(nr_pages, &mce_bad_pages); + return 0; + } + set_page_hwpoison_huge_page(hpage); + res = dequeue_hwpoisoned_huge_page(hpage); + action_result(pfn, "free huge", + res ? IGNORED : DELAYED); + unlock_page(hpage); + return res; } else { action_result(pfn, "high order kernel", IGNORED); return -EBUSY; @@ -1147,16 +1159,26 @@ int unpoison_memory(unsigned long pfn) page = compound_head(p); if (!PageHWPoison(p)) { - pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn); + pr_info("MCE: Page was already unpoisoned %#lx\n", pfn); return 0; } nr_pages = 1 << compound_order(page); if (!get_page_unless_zero(page)) { + /* + * 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)) { + pr_debug("MCE: Memory failure is now running on free hugepage %#lx\n", pfn); + return 0; + } if (TestClearPageHWPoison(p)) atomic_long_sub(nr_pages, &mce_bad_pages); - pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn); + pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn); return 0; } @@ -1168,12 +1190,12 @@ int unpoison_memory(unsigned long pfn) * the free buddy page pool. */ if (TestClearPageHWPoison(page)) { - pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn); + pr_info("MCE: Software-unpoisoned page %#lx\n", pfn); atomic_long_sub(nr_pages, &mce_bad_pages); freeit = 1; + if (PageHuge(page)) + clear_page_hwpoison_huge_page(page); } - if (PageHuge(p)) - clear_page_hwpoison_huge_page(page); unlock_page(page); put_page(page); @@ -1187,7 +1209,11 @@ 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); + if (PageHuge(p)) + return alloc_huge_page_node(page_hstate(compound_head(p)), + nid); + else + return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0); } /* @@ -1215,14 +1241,21 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags) * was free. */ set_migratetype_isolate(p); + /* + * When the target page is a free hugepage, just remove it + * from free hugepage list. + */ 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); + if (PageHuge(p)) { + pr_info("get_any_page: %#lx free huge page\n", pfn); + ret = dequeue_hwpoisoned_huge_page(compound_head(p)); + } else if (is_free_buddy_page(p)) { + pr_info("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", + pr_info("get_any_page: %#lx: unknown zero refcount page type %lx\n", pfn, p->flags); ret = -EIO; } @@ -1235,6 +1268,46 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags) 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); + + ret = get_any_page(page, pfn, flags); + if (ret < 0) + return ret; + if (ret == 0) + goto done; + + if (PageHWPoison(hpage)) { + put_page(hpage); + pr_debug("soft offline: %#lx hugepage already poisoned\n", pfn); + return -EBUSY; + } + + /* Keep page count to indicate a given hugepage is isolated. */ + + list_add(&hpage->lru, &pagelist); + ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0); + if (ret) { + putback_lru_pages(&pagelist); + pr_debug("soft offline: %#lx: migration failed %d, type %lx\n", + pfn, ret, page->flags); + if (ret > 0) + ret = -EIO; + return ret; + } +done: + if (!PageHWPoison(hpage)) + atomic_long_add(1 << compound_order(hpage), &mce_bad_pages); + set_page_hwpoison_huge_page(hpage); + dequeue_hwpoisoned_huge_page(hpage); + /* keep elevated page count for bad page */ + return ret; +} + /** * soft_offline_page - Soft offline a page. * @page: page to offline @@ -1262,6 +1335,9 @@ int soft_offline_page(struct page *page, int flags) int ret; unsigned long pfn = page_to_pfn(page); + if (PageHuge(page)) + return soft_offline_huge_page(page, flags); + ret = get_any_page(page, pfn, flags); if (ret < 0) return ret; @@ -1288,7 +1364,7 @@ int soft_offline_page(struct page *page, int flags) goto done; } if (!PageLRU(page)) { - pr_debug("soft_offline: %#lx: unknown non LRU page type %lx\n", + pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", pfn, page->flags); return -EIO; } @@ -1302,7 +1378,7 @@ int soft_offline_page(struct page *page, int flags) if (PageHWPoison(page)) { unlock_page(page); put_page(page); - pr_debug("soft offline: %#lx page already poisoned\n", pfn); + pr_info("soft offline: %#lx page already poisoned\n", pfn); return -EBUSY; } @@ -1323,7 +1399,7 @@ int soft_offline_page(struct page *page, int flags) put_page(page); if (ret == 1) { ret = 0; - pr_debug("soft_offline: %#lx: invalidated\n", pfn); + pr_info("soft_offline: %#lx: invalidated\n", pfn); goto done; } @@ -1339,13 +1415,13 @@ int soft_offline_page(struct page *page, int flags) 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", + pr_info("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", + pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n", pfn, ret, page_count(page), page->flags); } if (ret) |