[PATCH 4.4 107/163] mm/hwpoison: fix wrong num_poisoned_pages accounting

Greg Kroah-Hartman
2016-05-03T01:37:42Z

From: Minchan Kim <minchan@kernel.org>

commit d7e69488bd04de165667f6bc741c1c0ec6042ab9 upstream.

Currently, migration code increses num_poisoned_pages on *failed*
migration page as well as successfully migrated one at the trial of
memory-failure. It will make the stat wrong. As well, it marks the
page as PG_HWPoison even if the migration trial failed. It would mean
we cannot recover the corrupted page using memory-failure facility.

This patches fixes it.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/migrate.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -963,7 +963,13 @@ out:
dec_zone_page_state(page, NR_ISOLATED_ANON +
page_is_file_cache(page));
/* Soft-offlined page shouldn't go through lru cache list */
- if (reason == MR_MEMORY_FAILURE) {
+ if (reason == MR_MEMORY_FAILURE && rc == MIGRATEPAGE_SUCCESS) {
+ /*
+ * With this release, we free successfully migrated
+ * page and set PG_HWPoison on just freed page
+ * intentionally. Although it's rather weird, it's how
+ * HWPoison flag works at the moment.
+ */
put_page(page);
if (!test_set_page_hwpoison(page))
num_poisoned_pages_inc();