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Subject[PATCH AUTOSEL for 4.9 146/190] mm: hwpoison: call shake_page() after try_to_unmap() for mlocked page
From: Naoya Horiguchi <>

[ Upstream commit 286c469a988fbaf68e3a97ddf1e6c245c1446968 ]

Memory error handler calls try_to_unmap() for error pages in various
states. If the error page is a mlocked page, error handling could fail
with "still referenced by 1 users" message. This is because the page is
linked to and stays in lru cache after the following call chain.


memory_failure() calls shake_page() to hanlde the similar issue, but
current code doesn't cover because shake_page() is called only before
try_to_unmap(). So this patches adds shake_page().

Fixes: 23a003bfd23ea9ea0b7756b920e51f64b284b468 ("mm/madvise: pass return code of memory_failure() to userspace")
Signed-off-by: Naoya Horiguchi <>
Reported-by: kernel test robot <>
Cc: Xiaolong Ye <>
Cc: Chen Gong <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Sasha Levin <>
mm/memory-failure.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5aa71a82ca73..851efb004857 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -921,6 +921,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
int ret;
int kill = 1, forcekill;
struct page *hpage = *hpagep;
+ bool mlocked = PageMlocked(hpage);

* Here we are interested only in user-mapped pages, so skip any
@@ -984,6 +985,13 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n",
pfn, page_mapcount(hpage));

+ /*
+ * try_to_unmap() might put mlocked page in lru cache, so call
+ * shake_page() again to ensure that it's flushed.
+ */
+ if (mlocked)
+ shake_page(hpage, 0);
* Now that the dirty bit has been propagated to the
* struct page and all unmaps done we can decide if
 \ /
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