The patch titled
Subject: mm/hugetlb: fix potential race with try_memory_failure_hugetlb()
has been added to the -mm mm-unstable branch. Its filename is
mm-hugetlb-fix-potential-race-with-try_memory_failure_hugetlb.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-fix-potential-race-with-try_memory_failure_hugetlb.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/hugetlb: fix potential race with try_memory_failure_hugetlb()
Date: Wed, 10 Jul 2024 16:14:45 +0800
There is a potential race between __update_and_free_hugetlb_folio() and
try_memory_failure_hugetlb():
CPU1 CPU2
__update_and_free_hugetlb_folio try_memory_failure_hugetlb
spin_lock_irq(&hugetlb_lock);
__get_huge_page_for_hwpoison
folio_test_hugetlb
-- It's still hugetlb folio.
folio_test_hugetlb_raw_hwp_unreliable
-- raw_hwp_unreliable flag is not set yet.
folio_set_hugetlb_hwpoison
-- raw_hwp_unreliable flag might
be set.
spin_unlock_irq(&hugetlb_lock);
spin_lock_irq(&hugetlb_lock);
__folio_clear_hugetlb(folio);
-- Hugetlb flag is cleared but too late!
spin_unlock_irq(&hugetlb_lock);
When this race occurs, raw error pages will hit pcplists/buddy. Fix this
issue by deferring folio_test_hugetlb_raw_hwp_unreliable() until
__folio_clear_hugetlb() is done. The raw_hwp_unreliable flag cannot be
set after hugetlb folio flag is cleared.
Link: https://lkml.kernel.org/r/20240710081445.3307355-1-linmiaohe@xxxxxxxxxx
Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/mm/hugetlb.c~mm-hugetlb-fix-potential-race-with-try_memory_failure_hugetlb
+++ a/mm/hugetlb.c
@@ -1706,13 +1706,6 @@ static void __update_and_free_hugetlb_fo
return;
/*
- * If we don't know which subpages are hwpoisoned, we can't free
- * the hugepage, so it's leaked intentionally.
- */
- if (folio_test_hugetlb_raw_hwp_unreliable(folio))
- return;
-
- /*
* If folio is not vmemmap optimized (!clear_flag), then the folio
* is no longer identified as a hugetlb page. hugetlb_vmemmap_restore_folio
* can only be passed hugetlb pages and will BUG otherwise.
@@ -1730,6 +1723,13 @@ static void __update_and_free_hugetlb_fo
}
/*
+ * If we don't know which subpages are hwpoisoned, we can't free
+ * the hugepage, so it's leaked intentionally.
+ */
+ if (folio_test_hugetlb_raw_hwp_unreliable(folio))
+ return;
+
+ /*
* Move PageHWPoison flag from head page to the raw error pages,
* which makes any healthy subpages reusable.
*/
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-memory-failure-remove-obsolete-mf_msg_different_compound.patch
mm-hugetlb-fix-potential-race-with-try_memory_failure_hugetlb.patch
