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mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages

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commit 12df140f0bdfae5dcfc81800970dd7f6f632e00c upstream.

The h->*_huge_pages counters are protected by the hugetlb_lock, but
alloc_huge_page has a corner case where it can decrement the counter
outside of the lock.

This could lead to a corrupted value of h->resv_huge_pages, which we have
observed on our systems.

Take the hugetlb_lock before decrementing h->resv_huge_pages to avoid a
potential race.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: a88c769548 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count")
Signed-off-by: Rik van Riel <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Glen McCready <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Mike Kravetz <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Rik van Riel 2022-10-17 20:25:05 -04:00 • committed by Greg Kroah-Hartman
commit 11993652d0
1 changed files with 1 additions and 1 deletions
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2
mm/hugetlb.c
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@ -2218,11 +2218,11 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
if (!page)
goto out_uncharge_cgroup;
spin_lock(&hugetlb_lock);
if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
SetPagePrivate(page);
h->resv_huge_pages--;
}
spin_lock(&hugetlb_lock);
list_move(&page->lru, &h->hugepage_activelist);
/* Fall through */
}