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

From: Naoya Horiguchi
Date: Wed Apr 15 2015 - 03:27:58 EST

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 a broken behavior.

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@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v3.4+
mm/memory-failure.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git v4.0.orig/mm/memory-failure.c v4.0/mm/memory-failure.c
index d487f8dc6d39..2cc1d578144b 100644
--- v4.0.orig/mm/memory-failure.c
+++ v4.0/mm/memory-failure.c
@@ -1141,10 +1141,10 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
* 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.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/