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...

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@huawei.com 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@huawei.com Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap") Signed-off-by: Miaohe Lin linmiaohe@huawei.com Cc: Muchun Song muchun.song@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

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@huawei.com are

mm-memory-failure-remove-obsolete-mf_msg_different_compound.patch mm-hugetlb-fix-potential-race-with-try_memory_failure_hugetlb.patch