Commit 602498f9 authored May 05, 2015 by Naoya Horiguchi Committed by Linus Torvalds May 05, 2015

mm: soft-offline: fix num_poisoned_pages counting on concurrent events



If multiple soft offline events hit one free page/hugepage concurrently,
soft_offline_page() can handle the free page/hugepage multiple times,
which makes num_poisoned_pages counter increased more than once.  This
patch fixes this wrong counting by checking TestSetPageHWPoison for normal
papes and by checking the return value of dequeue_hwpoisoned_huge_page()
for hugepages.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Dean Nelson <dnelson@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: <stable@vger.kernel.org>	[3.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4d61ff6b

mm/memory-failure.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -1777,11 +1777,11 @@ int soft_offline_page(struct page *page, int flags)
		} else if (ret == 0) { /* for free pages */
		if (PageHuge(page)) {
		set_page_hwpoison_huge_page(hpage);
		dequeue_hwpoisoned_huge_page(hpage);
		if (!dequeue_hwpoisoned_huge_page(hpage))
		atomic_long_add(1 << compound_order(hpage),
		&num_poisoned_pages);
		} else {
		SetPageHWPoison(page);
		if (!TestSetPageHWPoison(page))
		atomic_long_inc(&num_poisoned_pages);
		}
		}

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