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Message-Id: <20211227151334.954562629@linuxfoundation.org>
Date: Mon, 27 Dec 2021 16:31:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Naoya Horiguchi <naoya.horiguchi@....com>,
Fei Luo <luofei@...cloud.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.15 103/128] mm, hwpoison: fix condition in free hugetlb page path
From: Naoya Horiguchi <naoya.horiguchi@....com>
commit e37e7b0b3bd52ec4f8ab71b027bcec08f57f1b3b upstream.
When a memory error hits a tail page of a free hugepage,
__page_handle_poison() is expected to be called to isolate the error in
4kB unit, but it's not called due to the outdated if-condition in
memory_failure_hugetlb(). This loses the chance to isolate the error in
the finer unit, so it's not optimal. Drop the condition.
This "(p != head && TestSetPageHWPoison(head)" condition is based on the
old semantics of PageHWPoison on hugepage (where PG_hwpoison flag was
set on the subpage), so it's not necessray any more. By getting to set
PG_hwpoison on head page for hugepages, concurrent error events on
different subpages in a single hugepage can be prevented by
TestSetPageHWPoison(head) at the beginning of memory_failure_hugetlb().
So dropping the condition should not reopen the race window originally
mentioned in commit b985194c8c0a ("hwpoison, hugetlb:
lock_page/unlock_page does not match for handling a free hugepage")
[naoya.horiguchi@...ux.dev: fix "HardwareCorrupted" counter]
Link: https://lkml.kernel.org/r/20211220084851.GA1460264@u2004
Link: https://lkml.kernel.org/r/20211210110208.879740-1-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
Reported-by: Fei Luo <luofei@...cloud.com>
Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
Cc: <stable@...r.kernel.org> [5.14+]
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
mm/memory-failure.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1437,17 +1437,12 @@ static int memory_failure_hugetlb(unsign
if (!(flags & MF_COUNT_INCREASED)) {
res = get_hwpoison_page(p, flags);
if (!res) {
- /*
- * Check "filter hit" and "race with other subpage."
- */
lock_page(head);
- if (PageHWPoison(head)) {
- if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
- || (p != head && TestSetPageHWPoison(head))) {
+ if (hwpoison_filter(p)) {
+ if (TestClearPageHWPoison(head))
num_poisoned_pages_dec();
- unlock_page(head);
- return 0;
- }
+ unlock_page(head);
+ return 0;
}
unlock_page(head);
res = MF_FAILED;
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