linux-kernel - [PATCH 5.13 122/127] mm/hwpoison: retry with shake

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Date:   Tue, 24 Aug 2021 12:56:02 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Naoya Horiguchi <naoya.horiguchi@....com>,
        Tony Luck <tony.luck@...el.com>,
        Yang Shi <shy828301@...il.com>,
        Oscar Salvador <osalvador@...e.de>,
        Muchun Song <songmuchun@...edance.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.13 122/127] mm/hwpoison: retry with shake_page() for unhandlable pages

From: Naoya Horiguchi <naoya.horiguchi@....com>

[ Upstream commit fcc00621d88b274b5dffd8daeea71d0e4c28b84e ]

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.

[naoya.horiguchi@....com: get_any_page(): return -EIO when retry limit reached]
  Link: https://lkml.kernel.org/r/20210819001958.2365157-1-naoya.horiguchi@linux.dev

Link: https://lkml.kernel.org/r/20210817053703.2267588-1-naoya.horiguchi@linux.dev
Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
Reported-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Yang Shi <shy828301@...il.com>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: Muchun Song <songmuchun@...edance.com>
Cc: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: <stable@...r.kernel.org>		[5.13+]
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/memory-failure.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 18e83150194a..624763fdecc5 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -990,7 +990,7 @@ 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)) {
 		/*
@@ -1043,9 +1043,15 @@ try_again:
 			}
 			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;
+			}
+			ret = -EIO;
 			goto out;
 		}
 	}
-- 
2.30.2