| From b985194c8c0a130ed155b71662e39f7eaea4876f Mon Sep 17 00:00:00 2001 |
| From: Chen Yucong <slaoub@gmail.com> |
| Date: Thu, 22 May 2014 11:54:15 -0700 |
| Subject: hwpoison, hugetlb: lock_page/unlock_page does not match for handling a free hugepage |
| |
| From: Chen Yucong <slaoub@gmail.com> |
| |
| commit b985194c8c0a130ed155b71662e39f7eaea4876f upstream. |
| |
| For handling a free hugepage in memory failure, the race will happen if |
| another thread hwpoisoned this hugepage concurrently. So we need to |
| check PageHWPoison instead of !PageHWPoison. |
| |
| If hwpoison_filter(p) returns true or a race happens, then we need to |
| unlock_page(hpage). |
| |
| Signed-off-by: Chen Yucong <slaoub@gmail.com> |
| Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
| Tested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
| Reviewed-by: Andi Kleen <ak@linux.intel.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/memory-failure.c | 15 ++++++++------- |
| 1 file changed, 8 insertions(+), 7 deletions(-) |
| |
| --- a/mm/memory-failure.c |
| +++ b/mm/memory-failure.c |
| @@ -1083,15 +1083,16 @@ int memory_failure(unsigned long pfn, in |
| return 0; |
| } else if (PageHuge(hpage)) { |
| /* |
| - * Check "just unpoisoned", "filter hit", and |
| - * "race with other subpage." |
| + * Check "filter hit" and "race with other subpage." |
| */ |
| lock_page(hpage); |
| - if (!PageHWPoison(hpage) |
| - || (hwpoison_filter(p) && TestClearPageHWPoison(p)) |
| - || (p != hpage && TestSetPageHWPoison(hpage))) { |
| - atomic_long_sub(nr_pages, &num_poisoned_pages); |
| - return 0; |
| + if (PageHWPoison(hpage)) { |
| + if ((hwpoison_filter(p) && TestClearPageHWPoison(p)) |
| + || (p != hpage && TestSetPageHWPoison(hpage))) { |
| + atomic_long_sub(nr_pages, &num_poisoned_pages); |
| + unlock_page(hpage); |
| + return 0; |
| + } |
| } |
| set_page_hwpoison_huge_page(hpage); |
| res = dequeue_hwpoisoned_huge_page(hpage); |