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From:   Naoya Horiguchi <naoya.horiguchi@linux.dev>
To:     linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Tony Luck <tony.luck@intel.com>,
        Oscar Salvador <osalvador@suse.de>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Michal Hocko <mhocko@suse.com>, Yang Shi <shy828301@gmail.com>,
        David Hildenbrand <david@redhat.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH v1] mm, hwpoison: add is_free_buddy_page() in HWPoisonHandlable()
Date:   Thu,  9 Sep 2021 09:41:31 +0900
Message-Id: <20210909004131.163221-1-naoya.horiguchi@linux.dev>
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From: Naoya Horiguchi <naoya.horiguchi@nec.com>

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@vger.kernel.org>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
 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)
-- 
2.25.1