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Message-ID: <20230708085744.3599311-9-linmiaohe@huawei.com>
Date: Sat, 8 Jul 2023 16:57:44 +0800
From: Miaohe Lin <linmiaohe@...wei.com>
To: <akpm@...ux-foundation.org>, <naoya.horiguchi@....com>
CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
<linmiaohe@...wei.com>
Subject: [PATCH 8/8] mm: memory-failure: fix race window when trying to get hugetlb folio
page_folio() is fetched before calling get_hwpoison_hugetlb_folio()
without hugetlb_lock being held. So hugetlb page could be demoted
before get_hwpoison_hugetlb_folio() holding hugetlb_lock but after
page_folio() is fetched. So get_hwpoison_hugetlb_folio() will hold
unexpected extra refcnt of hugetlb folio while leaving demoted page
un-refcnted.
Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
mm/memory-failure.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 76d88d27cdbe..066bf57f2d22 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1388,8 +1388,14 @@ static int __get_hwpoison_page(struct page *page, unsigned long flags)
bool hugetlb = false;
ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, false);
- if (hugetlb)
- return ret;
+ if (hugetlb) {
+ if (folio == page_folio(page))
+ return ret;
+ if (ret > 0) {
+ folio_put(folio);
+ folio = page_folio(page);
+ }
+ }
/*
* This check prevents from calling folio_try_get() for any
@@ -1478,8 +1484,12 @@ static int __get_unpoison_page(struct page *page)
bool hugetlb = false;
ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, true);
- if (hugetlb)
- return ret;
+ if (hugetlb) {
+ if (folio == page_folio(page))
+ return ret;
+ if (ret > 0)
+ folio_put(folio);
+ }
/*
* PageHWPoisonTakenOff pages are not only marked as PG_hwpoison,
--
2.33.0
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