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.
Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count")
Cc: stable@xxxxxxxxxx
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Glen McCready <gkmccready@xxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b586cdd75930..dede0337c07c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2924,11 +2924,11 @@ 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_irq(&hugetlb_lock);
if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
SetHPageRestoreReserve(page);
h->resv_huge_pages--;
}
- spin_lock_irq(&hugetlb_lock);
list_add(&page->lru, &h->hugepage_activelist);
set_page_refcounted(page);
/* Fall through */
--
2.37.2
