[PATCH 6/6] mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active

From: Muchun Song <songmuchun@bytedance.com>
To: mike.kravetz@oracle.com, akpm@linux-foundation.org
Cc: hillf.zj@alibaba-inc.com, n-horiguchi@ah.jp.nec.com,
	ak@linux.intel.com, yongjun_wei@trendmicro.com.cn,
	mhocko@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH 6/6] mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active
Date: Mon,  4 Jan 2021 14:58:43 +0800	[thread overview]
Message-ID: <20210104065843.5658-6-songmuchun@bytedance.com> (raw)
In-Reply-To: <20210104065843.5658-1-songmuchun@bytedance.com>

The page_huge_active() can be called from scan_movable_pages() which
do not hold a reference count to the HugeTLB page. So when we call
page_huge_active() from scan_movable_pages(), the HugeTLB page can
be freed parallel. Then we will trigger a BUG_ON which is in the
page_huge_active() when CONFIG_DEBUG_VM is enabled. Just remove the
VM_BUG_ON_PAGE.

Fixes: 7e1f049efb86 ("mm: hugetlb: cleanup using paeg_huge_active()")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/hugetlb.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 5c2f64f53177..4c8631114e88 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1360,7 +1360,6 @@ struct hstate *size_to_hstate(unsigned long size)
  */
 bool page_huge_active(struct page *page)
 {
-	VM_BUG_ON_PAGE(!PageHuge(page), page);
 	return PageHead(page) && PagePrivate(&page[1]);
 }
 
-- 
2.11.0

