[PATCH 5.14 001/162] mm, hwpoison: add is_free_buddy_page() in HWPoisonHandlable()

From: Greg Kroah-Hartman
Date: Mon Sep 27 2021 - 13:18:42 EST

From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>

commit acfa299a4a63a58e5e81a87cb16798f20d35f7d7 upstream.

Commit fcc00621d88b ("mm/hwpoison: retry with shake_page() for
unhandlable pages") changed 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.

Link: https://lkml.kernel.org/r/20210909004131.163221-1-naoya.horiguchi@xxxxxxxxx
Fixes: fcc00621d88b ("mm/hwpoison: retry with shake_page() for unhandlable pages")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
mm/memory-failure.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1127,7 +1127,7 @@ static int page_action(struct page_state
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)