The patch titled
Subject: mm/hugetlb: fix potential race in __update_and_free_hugetlb_folio()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-hugetlb-fix-potential-race-in-__update_and_free_hugetlb_folio.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-in-__update_and_free_hugetlb_folio.patch
This patch will later appear in the mm-hotfixes-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 in __update_and_free_hugetlb_folio()
Date: Mon, 8 Jul 2024 10:51:27 +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
folio_test_hugetlb
-- It's still hugetlb folio.
folio_clear_hugetlb_hwpoison
spin_lock_irq(&hugetlb_lock);
__get_huge_page_for_hwpoison
folio_set_hugetlb_hwpoison
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 the above race occurs, raw error page info will be leaked. Even
worse, raw error pages won't have hwpoisoned flag set and hit
pcplists/buddy. Fix this issue by deferring
folio_clear_hugetlb_hwpoison() until __folio_clear_hugetlb() is done. So
all raw error pages will have hwpoisoned flag set.
Link: https://lkml.kernel.org/r/20240708025127.107713-1-linmiaohe@xxxxxxxxxx
Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Acked-by: Muchun Song <muchun.song@xxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
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-in-__update_and_free_hugetlb_folio
+++ a/mm/hugetlb.c
@@ -1726,13 +1726,6 @@ static void __update_and_free_hugetlb_fo
}
/*
- * Move PageHWPoison flag from head page to the raw error pages,
- * which makes any healthy subpages reusable.
- */
- if (unlikely(folio_test_hwpoison(folio)))
- folio_clear_hugetlb_hwpoison(folio);
-
- /*
* If vmemmap pages were allocated above, then we need to clear the
* hugetlb flag under the hugetlb lock.
*/
@@ -1742,6 +1735,13 @@ static void __update_and_free_hugetlb_fo
spin_unlock_irq(&hugetlb_lock);
}
+ /*
+ * Move PageHWPoison flag from head page to the raw error pages,
+ * which makes any healthy subpages reusable.
+ */
+ if (unlikely(folio_test_hwpoison(folio)))
+ folio_clear_hugetlb_hwpoison(folio);
+
folio_ref_unfreeze(folio, 1);
/*
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-hugetlb-fix-potential-race-in-__update_and_free_hugetlb_folio.patch
mm-memory-failure-remove-obsolete-mf_msg_different_compound.patch
