Commit 5596d9e8 authored by Miaohe Lin's avatar Miaohe Lin Committed by Andrew Morton
Browse files

mm/hugetlb: fix potential race in __update_and_free_hugetlb_folio() 

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: 32c87719 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap")
Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarMuchun Song <muchun.song@linux.dev>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 24be02a4

mm/hugetlb.c

+7 −7
Original line number Diff line number Diff line
@@ -1725,13 +1725,6 @@ static void __update_and_free_hugetlb_folio(struct hstate *h, 
		return;

	}



	/*

	 * 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_folio(struct hstate *h, 
		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);



	/*