Commit c2e7e00b authored Apr 28, 2016 by Konstantin Khlebnikov Committed by Linus Torvalds Apr 28, 2016

mm/memory-failure: fix race with compound page split/merge

get_hwpoison_page() must recheck relation between head and tail pages.

n-horiguchi said: without this recheck, the race causes kernel to pin an
irrelevant page, and finally makes kernel crash for refcount mismatch.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-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 b7341364

mm/memory-failure.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -888,7 +888,15 @@ int get_hwpoison_page(struct page *page)
		}
		}

		return get_page_unless_zero(head);
		if (get_page_unless_zero(head)) {
		if (head == compound_head(page))
		return 1;

		pr_info("MCE: %#lx cannot catch tail\n", page_to_pfn(page));
		put_page(head);
		}

		return 0;
		}
		EXPORT_SYMBOL_GPL(get_hwpoison_page);