diff options
| author | Liu Shixin <liushixin2@huawei.com> | 2025-03-05 11:54:09 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-03-17 22:06:50 -0700 |
| commit | 2273dea6b1e1fcdd06d207048a2cd563ed80111a (patch) | |
| tree | 7b91eca655d2676b821da68cef7377c6a74698c5 /mm/hugetlb.c | |
| parent | 114b480877698f7835a5ba95c6fbd97b63b119f6 (diff) | |
mm/hugetlb: update nr_huge_pages and surplus_huge_pages together
In alloc_surplus_hugetlb_folio(), we increase nr_huge_pages and
surplus_huge_pages separately. In the middle window, if we set
nr_hugepages to smaller and satisfy count < persistent_huge_pages(h), the
surplus_huge_pages will be increased by adjust_pool_surplus().
After adding delay in the middle window, we can reproduce the problem
easily by following step:
1. echo 3 > /proc/sys/vm/nr_overcommit_hugepages
2. mmap two hugepages. When nr_huge_pages=2 and surplus_huge_pages=1,
goto step 3.
3. echo 0 > /proc/sys/vm/nr_huge_pages
Finally, nr_huge_pages is less than surplus_huge_pages.
To fix the problem, call only_alloc_fresh_hugetlb_folio() instead and
move down __prep_account_new_huge_page() into the hugetlb_lock.
Link: https://lkml.kernel.org/r/20250305035409.2391344-1-liushixin2@huawei.com
Fixes: 0c397daea1d4 ("mm, hugetlb: further simplify hugetlb allocation API")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 438de55dd38d..af9b8c1fca67 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2259,12 +2259,21 @@ static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h, goto out_unlock; spin_unlock_irq(&hugetlb_lock); - folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask); + folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL); if (!folio) return NULL; + hugetlb_vmemmap_optimize_folio(h, folio); + spin_lock_irq(&hugetlb_lock); /* + * nr_huge_pages needs to be adjusted within the same lock cycle + * as surplus_pages, otherwise it might confuse + * persistent_huge_pages() momentarily. + */ + __prep_account_new_huge_page(h, nid); + + /* * We could have raced with the pool size change. * Double check that and simply deallocate the new page * if we would end up overcommiting the surpluses. Abuse |