From 286c469a988fbaf68e3a97ddf1e6c245c1446968 Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Wed, 3 May 2017 14:56:22 -0700 Subject: [PATCH] mm: hwpoison: call shake_page() after try_to_unmap() for mlocked page 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.nec.com 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 --- mm/memory-failure.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 9d87fcab96c9..73066b80d14a 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -916,6 +916,7 @@ 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 @@ -979,6 +980,13 @@ static bool 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 -- 2.20.1