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mm: memory-failure: fix race window when trying to get hugetlb folio 

page_folio() is fetched before calling get_hwpoison_hugetlb_folio()
without hugetlb_lock being held.  So hugetlb page could be demoted before
get_hwpoison_hugetlb_folio() holding hugetlb_lock but after page_folio()
is fetched.  So get_hwpoison_hugetlb_folio() will hold unexpected extra
refcnt of hugetlb folio while leaving demoted page un-refcnted.

Link: https://lkml.kernel.org/r/20230711055016.2286677-9-linmiaohe@huawei.com
Fixes: 25182f05ff ("mm,hwpoison: fix race with hugetlb page allocation")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2023-07-11 13:50:16 +08:00 committed by Andrew Morton
parent a363d1224b
commit d31155b8f2
1 changed files with 16 additions and 4 deletions
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20
mm/memory-failure.c
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@ -1383,8 +1383,15 @@ static int __get_hwpoison_page(struct page *page, unsigned long flags)
bool hugetlb = false;
ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, false);
if (hugetlb)
return ret;
if (hugetlb) {
/* Make sure hugetlb demotion did not happen from under us. */
if (folio == page_folio(page))
return ret;
if (ret > 0) {
folio_put(folio);
folio = page_folio(page);
}
}
/*
* This check prevents from calling folio_try_get() for any
@ -1473,8 +1480,13 @@ static int __get_unpoison_page(struct page *page)
bool hugetlb = false;
ret = get_hwpoison_hugetlb_folio(folio, &hugetlb, true);
if (hugetlb)
return ret;
if (hugetlb) {
/* Make sure hugetlb demotion did not happen from under us. */
if (folio == page_folio(page))
return ret;
if (ret > 0)
folio_put(folio);
}
/*
* PageHWPoisonTakenOff pages are not only marked as PG_hwpoison,