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...

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@huawei.com 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@huawei.com Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap") Signed-off-by: Miaohe Lin linmiaohe@huawei.com Acked-by: Muchun Song muchun.song@linux.dev Reviewed-by: Oscar Salvador osalvador@suse.de 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-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@huawei.com are

mm-hugetlb-fix-potential-race-in-__update_and_free_hugetlb_folio.patch mm-memory-failure-remove-obsolete-mf_msg_different_compound.patch