| Message ID | 20221017202505.0e6a4fcd@imladris.surriel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages | expand |
On 10/17/22 20:25, Rik van Riel wrote: > 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@kernel.org > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Glen McCready <gkmccready@meta.com> > Cc: Mike Kravetz <mike.kravetz@oracle.com> > Cc: Muchun Song <songmuchun@bytedance.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Rik van Riel <riel@surriel.com> > --- > mm/hugetlb.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Thanks Rik! That case did slip through the cracks. Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
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 */
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@kernel.org Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Glen McCready <gkmccready@meta.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rik van Riel <riel@surriel.com> --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)