From: Muchun Song <songmuchun@bytedance.com>
To: mike.kravetz@oracle.com, akpm@linux-foundation.org,
mhocko@suse.com, osalvador@suse.de
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH] mm: hugetlb: fix a race between memory-failure/soft_offline and gather_surplus_pages
Date: Wed, 21 Apr 2021 14:02:59 +0800 [thread overview]
Message-ID: <20210421060259.67554-1-songmuchun@bytedance.com> (raw)
The possible bad scenario:
CPU0: CPU1:
gather_surplus_pages()
page = alloc_surplus_huge_page()
memory_failure_hugetlb()
get_hwpoison_page(page)
__get_hwpoison_page(page)
get_page_unless_zero(page)
zero = put_page_testzero(page)
VM_BUG_ON_PAGE(!zero, page)
enqueue_huge_page(h, page)
put_page(page)
The refcount can possibly be increased by memory-failure or soft_offline
handlers, we can trigger VM_BUG_ON_PAGE and wrongly add the page to the
hugetlb pool list.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
mm/hugetlb.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3476aa06da70..6c96332db34b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2145,17 +2145,14 @@ static int gather_surplus_pages(struct hstate *h, long delta)
/* Free the needed pages to the hugetlb pool */
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
- int zeroed;
-
if ((--needed) < 0)
break;
/*
- * This page is now managed by the hugetlb allocator and has
- * no users -- drop the buddy allocator's reference.
+ * The refcount can possibly be increased by memory-failure or
+ * soft_offline handlers.
*/
- zeroed = put_page_testzero(page);
- VM_BUG_ON_PAGE(!zeroed, page);
- enqueue_huge_page(h, page);
+ if (likely(put_page_testzero(page)))
+ enqueue_huge_page(h, page);
}
free:
spin_unlock_irq(&hugetlb_lock);
--
2.11.0
next reply other threads:[~2021-04-21 6:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 6:02 Muchun Song [this message]
2021-04-21 8:03 ` [PATCH] mm: hugetlb: fix a race between memory-failure/soft_offline and gather_surplus_pages Michal Hocko
2021-04-21 8:15 ` [External] " Muchun Song
2021-04-21 8:21 ` Oscar Salvador
2021-04-21 8:41 ` Muchun Song
2021-04-21 8:49 ` Oscar Salvador
2021-04-21 8:58 ` Muchun Song
2021-04-21 8:43 ` Michal Hocko
2021-04-21 8:25 ` Michal Hocko
2021-04-21 8:33 ` HORIGUCHI NAOYA(堀口 直也)
2021-04-21 9:02 ` [External] " Muchun Song
2021-04-21 18:03 ` Mike Kravetz
2021-04-22 8:27 ` HORIGUCHI NAOYA(堀口 直也)
2021-04-23 8:01 ` HORIGUCHI NAOYA(堀口 直也)
2021-04-28 7:46 ` [PATCH] mm,hwpoison: fix race with compound page allocation Naoya Horiguchi
2021-04-28 8:23 ` Oscar Salvador
2021-04-28 9:18 ` HORIGUCHI NAOYA(堀口 直也)
2021-05-06 1:31 ` [PATCH v2] " Naoya Horiguchi
2021-05-06 8:51 ` Oscar Salvador
2021-05-07 4:17 ` HORIGUCHI NAOYA(堀口 直也)
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