Commit 3e030ecc authored May 22, 2014 by Naoya Horiguchi Committed by Linus Torvalds May 23, 2014

mm/memory-failure.c: fix memory leak by race between poison and unpoison



When a memory error happens on an in-use page or (free and in-use)
hugepage, the victim page is isolated with its refcount set to one.

When you try to unpoison it later, unpoison_memory() calls put_page()
for it twice in order to bring the page back to free page pool (buddy or
free hugepage list).  However, if another memory error occurs on the
page which we are unpoisoning, memory_failure() returns without
releasing the refcount which was incremented in the same call at first,
which results in memory leak and unconsistent num_poisoned_pages
statistics.  This patch fixes it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: <stable@vger.kernel.org>    [2.6.32+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ad0f614e

mm/memory-failure.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1153,6 +1153,8 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
		*/
		if (!PageHWPoison(p)) {
		printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
		atomic_long_sub(nr_pages, &num_poisoned_pages);
		put_page(hpage);
		res = 0;
		goto out;
		}

Admin message