Commit 1e0e635b authored Sep 08, 2015 by Wanpeng Li Committed by Linus Torvalds Sep 08, 2015

mm/hwpoison: fix PageHWPoison test/set race



There is a race between madvise_hwpoison path and memory_failure:

 CPU0					CPU1

madvise_hwpoison
get_user_pages_fast
PageHWPoison check (false)
					memory_failure
					TestSetPageHWPoison
soft_offline_page
PageHWPoison check (true)
return -EBUSY (without put_page)

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Suggested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7d1900c7

mm/memory-failure.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1719,6 +1719,8 @@ int soft_offline_page(struct page *page, int flags)

		if (PageHWPoison(page)) {
		pr_info("soft offline: %#lx page already poisoned\n", pfn);
		if (flags & MF_COUNT_INCREASED)
		put_page(page);
		return -EBUSY;
		}
		if (!PageHuge(page) && PageTransHuge(hpage)) {

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