From 0ebff32c3637e0ed551c017eb9599ac108ab36aa Mon Sep 17 00:00:00 2001 From: Xishi Qiu Date: Fri, 22 Feb 2013 16:33:59 -0800 Subject: [PATCH] memory-failure: fix an error of mce_bad_pages statistics When doing $ echo paddr > /sys/devices/system/memory/soft_offline_page to offline a *free* page, the value of mce_bad_pages will be added, and the page is set HWPoison flag, but it is still managed by page buddy alocator. $ cat /proc/meminfo | grep HardwareCorrupted shows the value. If we offline the same page, the value of mce_bad_pages will be added *again*, this means the value is incorrect now. Assume the page is still free during this short time. soft_offline_page() get_any_page() "else if (is_free_buddy_page(p))" branch return 0 "goto done"; "atomic_long_add(1, &mce_bad_pages);" This patch: Move poisoned page check at the beginning of the function in order to fix the error. Signed-off-by: Xishi Qiu Signed-off-by: Jiang Liu Tested-by: Naoya Horiguchi Cc: Borislav Petkov Cc: Wanpeng Li Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory-failure.c | 38 +++++++++++++++++--------------------- 1 file changed, 17 insertions(+), 21 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index c6e4dd3..1a9242c 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1419,18 +1419,17 @@ static int soft_offline_huge_page(struct page *page, int flags) unsigned long pfn = page_to_pfn(page); struct page *hpage = compound_head(page); + if (PageHWPoison(hpage)) { + pr_info("soft offline: %#lx hugepage already poisoned\n", pfn); + return -EBUSY; + } + ret = get_any_page(page, pfn, flags); if (ret < 0) return ret; if (ret == 0) goto done; - if (PageHWPoison(hpage)) { - put_page(hpage); - pr_info("soft offline: %#lx hugepage already poisoned\n", pfn); - return -EBUSY; - } - /* Keep page count to indicate a given hugepage is isolated. */ ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, false, MIGRATE_SYNC); @@ -1441,12 +1440,11 @@ static int soft_offline_huge_page(struct page *page, int flags) return ret; } done: - if (!PageHWPoison(hpage)) - atomic_long_add(1 << compound_trans_order(hpage), - &mce_bad_pages); + /* keep elevated page count for bad page */ + atomic_long_add(1 << compound_trans_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; } @@ -1488,6 +1486,11 @@ int soft_offline_page(struct page *page, int flags) } } + if (PageHWPoison(page)) { + pr_info("soft offline: %#lx page already poisoned\n", pfn); + return -EBUSY; + } + ret = get_any_page(page, pfn, flags); if (ret < 0) return ret; @@ -1519,19 +1522,11 @@ int soft_offline_page(struct page *page, int 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_info("soft offline: %#lx page already poisoned\n", pfn); - return -EBUSY; - } - + lock_page(page); + wait_on_page_writeback(page); /* * Try to invalidate first. This should work for * non dirty unmapped page cache pages. @@ -1583,8 +1578,9 @@ int soft_offline_page(struct page *page, int flags) return ret; done: + /* keep elevated page count for bad page */ atomic_long_add(1, &mce_bad_pages); SetPageHWPoison(page); - /* keep elevated page count for bad page */ + return ret; } -- 2.7.4