[PATCH v1] mm, hwpoison: add is_free_buddy_page() in HWPoisonHandlable()

From: Naoya Horiguchi
Date: Wed Sep 08 2021 - 20:46:17 EST

From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>

commit fcc00621d88b ("mm/hwpoison: retry with shake_page() for
unhandlable pages") changes the return value of __get_hwpoison_page() to
retry for transiently unhandlable cases. However, __get_hwpoison_page()
currently fails to properly judge buddy pages as handlable, so hard/soft
offline for buddy pages always fail as "unhandlable page". This is
totally regrettable.

So let's add is_free_buddy_page() in HWPoisonHandlable(), so that
__get_hwpoison_page() returns different return values between buddy
pages and unhandlable pages as intended.

Fixes: fcc00621d88b ("mm/hwpoison: retry with shake_page() for unhandlable pages")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
mm/memory-failure.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git v5.14-rc7-mmotm-2021-08-23-16-42/mm/memory-failure.c v5.14-rc7-mmotm-2021-08-23-16-42_patched/mm/memory-failure.c
index 60df8fcd0444..3416c55be810 100644
--- v5.14-rc7-mmotm-2021-08-23-16-42/mm/memory-failure.c
+++ v5.14-rc7-mmotm-2021-08-23-16-42_patched/mm/memory-failure.c
@@ -1126,7 +1126,7 @@ static int page_action(struct page_state *ps, struct page *p,
static inline bool HWPoisonHandlable(struct page *page)
- return PageLRU(page) || __PageMovable(page);
+ return PageLRU(page) || __PageMovable(page) || is_free_buddy_page(page);

static int __get_hwpoison_page(struct page *page)