From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm/memory-failure.c: move refcount only in !MF_COUNT_INCREASED
mce-test detected a test failure when injecting error to a thp tail page.
This is because we take page refcount of the tail page in
madvise_hwpoison() while the fix in commit a3e0f9e47d5e
("mm/memory-failure.c: transfer page count from head page to tail page
after split thp") assumes that we always take refcount on the head page.
When a real memory error happens we take refcount on the head page where
memory_failure() is called without MF_COUNT_INCREASED set, so it seems to
me that testing memory error on thp tail page using madvise makes little
sense.
This patch cancels moving refcount in !MF_COUNT_INCREASED for valid testing.
[akpm@xxxxxxxxxxxxxxxxxxxx: s/&&/&/]
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Cc: Chen Gong <gong.chen@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.9+: a3e0f9e47d5e]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN mm/memory-failure.c~mm-memory-failurec-move-refcount-only-in-mf_count_increased mm/memory-failure.c
--- a/mm/memory-failure.c~mm-memory-failurec-move-refcount-only-in-mf_count_increased
+++ a/mm/memory-failure.c
@@ -945,8 +945,10 @@ static int hwpoison_user_mappings(struct
* to it. Similarly, page lock is shifted.
*/
if (hpage != p) {
- put_page(hpage);
- get_page(p);
+ if (!(flags & MF_COUNT_INCREASED)) {
+ put_page(hpage);
+ get_page(p);
+ }
lock_page(p);
unlock_page(hpage);
*hpagep = p;
_
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