[PATCH v1] mm: bad_page() checks bad_flags instead of page->flags for hwpoison page

Naoya Horiguchi
2016-05-17T07:43:01Z

There's a race window between checking page->flags and unpoisoning, which
taints kernel with "BUG: Bad page state". That's overkill. It's safer to
use bad_flags to detect hwpoisoned page.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
mm/page_alloc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git tmp/mm/page_alloc.c tmp_patched/mm/page_alloc.c
index 5b269bc..4e0fa37 100644
--- tmp/mm/page_alloc.c
+++ tmp_patched/mm/page_alloc.c
@@ -522,8 +522,8 @@ static void bad_page(struct page *page, const char *reason,
static unsigned long nr_shown;
static unsigned long nr_unshown;

- /* Don't complain about poisoned pages */
- if (PageHWPoison(page)) {
+ /* Don't complain about hwpoisoned pages */
+ if (bad_flags == __PG_HWPOISON) {
page_mapcount_reset(page); /* remove PageBuddy */
return;
}
--
2.7.0