4.9-stable review patch. If anyone has any objections, please let me know.
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From: Naoya Horiguchi n-horiguchi@ah.jp.nec.com
[ 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.
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().
Fixes: 23a003bfd23ea9ea0b7756b920e51f64b284b468 ("mm/madvise: pass return code of memory_failure() to userspace") Link: http://lkml.kernel.org/r/20170417055948.GM31394@yexl-desktop Link: http://lkml.kernel.org/r/1493197841-23986-3-git-send-email-n-horiguchi@ah.jp... Signed-off-by: Naoya Horiguchi n-horiguchi@ah.jp.nec.com Reported-by: kernel test robot lkp@intel.com Cc: Xiaolong Ye xiaolong.ye@intel.com Cc: Chen Gong gong.chen@linux.intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/memory-failure.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -921,6 +921,7 @@ static int hwpoison_user_mappings(struct 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 @@ -985,6 +986,13 @@ static int hwpoison_user_mappings(struct 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