Patch "mm/memory-failure: call shake_page() when error hits thp tail page" has been added to the 4.0-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mm/memory-failure: call shake_page() when error hits thp tail page

to the 4.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mm-memory-failure-call-shake_page-when-error-hits-thp-tail-page.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 09789e5de18e4e442870b2d700831f5cb802eb05 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Tue, 5 May 2015 16:23:35 -0700
Subject: mm/memory-failure: call shake_page() when error hits thp tail page

From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

commit 09789e5de18e4e442870b2d700831f5cb802eb05 upstream.

Currently memory_failure() calls shake_page() to sweep pages out from
pcplists only when the victim page is 4kB LRU page or thp head page.
But we should do this for a thp tail page too.

Consider that a memory error hits a thp tail page whose head page is on
a pcplist when memory_failure() runs.  Then, the current kernel skips
shake_pages() part, so hwpoison_user_mappings() returns without calling
split_huge_page() nor try_to_unmap() because PageLRU of the thp head is
still cleared due to the skip of shake_page().

As a result, me_huge_page() runs for the thp, which is broken behavior.

One effect is a leak of the thp.  And another is to fail to isolate the
memory error, so later access to the error address causes another MCE,
which kills the processes which used the thp.

This patch fixes this problem by calling shake_page() for thp tail case.

Fixes: 385de35722c9 ("thp: allow a hwpoisoned head page to be put back to LRU")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Dean Nelson <dnelson@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Jin Dongming <jin.dongming@np.css.fujitsu.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 |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1141,10 +1141,10 @@ int memory_failure(unsigned long pfn, in
 	 * The check (unnecessarily) ignores LRU pages being isolated and
 	 * walked by the page reclaim code, however that's not a big loss.
 	 */
-	if (!PageHuge(p) && !PageTransTail(p)) {
-		if (!PageLRU(p))
-			shake_page(p, 0);
-		if (!PageLRU(p)) {
+	if (!PageHuge(p)) {
+		if (!PageLRU(hpage))
+			shake_page(hpage, 0);
+		if (!PageLRU(hpage)) {
 			/*
 			 * shake_page could have turned it free.
 			 */


Patches currently in stable-queue which might be from n-horiguchi@ah.jp.nec.com are

queue-4.0/mm-soft-offline-fix-num_poisoned_pages-counting-on-concurrent-events.patch
queue-4.0/mm-memory-failure-call-shake_page-when-error-hits-thp-tail-page.patch