diff mbox series

[7/8] mm: memory-failure: fetch compound head after extra page refcnt is held

Message ID 20230708085744.3599311-8-linmiaohe@huawei.com
State New
Headers
Series A few fixup and cleanup patches for memory-failure |

Commit Message

Miaohe Lin July 8, 2023, 8:57 a.m. UTC 
  Page might become thp, huge page or being splited after compound head
is fetched but before page refcnt is bumped. So hpage might be a tail
page leading to VM_BUG_ON_PAGE(PageTail(page)) in PageTransHuge().

Fixes: 415c64c1453a ("mm/memory-failure: split thp earlier in memory error handling")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/memory-failure.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Naoya Horiguchi July 10, 2023, 7:57 a.m. UTC | #1 
On Sat, Jul 08, 2023 at 04:57:43PM +0800, Miaohe Lin wrote:
> Page might become thp, huge page or being splited after compound head
> is fetched but before page refcnt is bumped. So hpage might be a tail
> page leading to VM_BUG_ON_PAGE(PageTail(page)) in PageTransHuge().
> 
> Fixes: 415c64c1453a ("mm/memory-failure: split thp earlier in memory error handling")
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>

Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
diff mbox series

Patch

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 0f93175ed862..76d88d27cdbe 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2179,8 +2179,6 @@  int memory_failure(unsigned long pfn, int flags)
 		goto unlock_mutex;
 	}
 
-	hpage = compound_head(p);
-
 	/*
 	 * We need/can do nothing about count=0 pages.
 	 * 1) it's a free page, and therefore in safe hand:
@@ -2219,6 +2217,7 @@  int memory_failure(unsigned long pfn, int flags)
 		}
 	}
 
+	hpage = compound_head(p);
 	if (PageTransHuge(hpage)) {
 		/*
 		 * The flag must be set after the refcount is bumped