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.
try_to_unmap_one
page_remove_rmap
clear_page_mlock
putback_lru_page
lru_cache_add
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().
Link: http://lkml.kernel.org/r/20170417055948.GM31394@yexl-desktop
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
mm/memory-failure.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git v4.11-rc6-mmotm-2017-04-13-14-50/mm/memory-failure.c v4.11-rc6-mmotm-2017-04-13-14-50_patched/mm/memory-failure.c
index 77cf9c3..57f07ec 100644
--- v4.11-rc6-mmotm-2017-04-13-14-50/mm/memory-failure.c
+++ v4.11-rc6-mmotm-2017-04-13-14-50_patched/mm/memory-failure.c
@@ -919,6 +919,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
bool unmap_success;
int kill = 1, forcekill;
struct page *hpage = *hpagep;
+ bool mlocked = PageMlocked(hpage);
/*
* Here we are interested only in user-mapped pages, so skip any
@@ -983,6 +984,13 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
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
* killing is needed or not. Only kill when the page
--
2.7.0
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