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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>,
        Muchun Song <songmuchun@bytedance.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Michal Hocko <mhocko@suse.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH v1] mm/hwpoison: Retry with shake_page() for unhandlable pages
Date:   Tue, 17 Aug 2021 14:37:03 +0900
Message-Id: <20210817053703.2267588-1-naoya.horiguchi@linux.dev>
MIME-Version: 1.0
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From: Naoya Horiguchi <naoya.horiguchi@nec.com>

HWPoisonHandlable() sometimes returns false for typical user pages
due to races with average memory events like transfers over LRU lists.
This causes failures in hwpoison handling.

There's retry code for such a case but does not work because the retry
loop reaches the retry limit too quickly before the page settles down to
handlable state. Let get_any_page() call shake_page() to fix it.

Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation")
Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: stable@vger.kernel.org # 5.13
---
 mm/memory-failure.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git v5.14-rc6/mm/memory-failure.c v5.14-rc6_patched/mm/memory-failure.c
index eefd823deb67..aa6592540f17 100644
--- v5.14-rc6/mm/memory-failure.c
+++ v5.14-rc6_patched/mm/memory-failure.c
@@ -1146,7 +1146,7 @@ static int __get_hwpoison_page(struct page *page)
 	 * unexpected races caused by taking a page refcount.
 	 */
 	if (!HWPoisonHandlable(head))
-		return 0;
+		return -EBUSY;
 
 	if (PageTransHuge(head)) {
 		/*
@@ -1199,9 +1199,14 @@ static int get_any_page(struct page *p, unsigned long flags)
 			}
 			goto out;
 		} else if (ret == -EBUSY) {
-			/* We raced with freeing huge page to buddy, retry. */
-			if (pass++ < 3)
+			/*
+			 * We raced with (possibly temporary) unhandlable
+			 * page, retry.
+			 */
+			if (pass++ < 3) {
+				shake_page(p, 1);
 				goto try_again;
+			}
 			goto out;
 		}
 	}
-- 
2.25.1