This is a note to let you know that I've just added the patch titled mm: hwpoison: fix thp split handling in memory_failure() to the 4.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-hwpoison-fix-thp-split-handling-in-memory_failure.patch and it can be found in the queue-4.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From c3901e722b2975666f42748340df798114742d6d Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Date: Thu, 10 Nov 2016 10:46:23 -0800 Subject: mm: hwpoison: fix thp split handling in memory_failure() From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> commit c3901e722b2975666f42748340df798114742d6d upstream. When memory_failure() runs on a thp tail page after pmd is split, we trigger the following VM_BUG_ON_PAGE(): page:ffffd7cd819b0040 count:0 mapcount:0 mapping: (null) index:0x1 flags: 0x1fffc000400000(hwpoison) page dumped because: VM_BUG_ON_PAGE(!page_count(p)) ------------[ cut here ]------------ kernel BUG at /src/linux-dev/mm/memory-failure.c:1132! memory_failure() passed refcount and page lock from tail page to head page, which is not needed because we can pass any subpage to split_huge_page(). Fixes: 61f5d698cc97 ("mm: re-enable THP") Link: http://lkml.kernel.org/r/1477961577-7183-1-git-send-email-n-horiguchi@xxxxxxxxxxxxx Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/memory-failure.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1112,10 +1112,10 @@ int memory_failure(unsigned long pfn, in } if (!PageHuge(p) && PageTransHuge(hpage)) { - lock_page(hpage); - if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) { - unlock_page(hpage); - if (!PageAnon(hpage)) + lock_page(p); + if (!PageAnon(p) || unlikely(split_huge_page(p))) { + unlock_page(p); + if (!PageAnon(p)) pr_err("Memory failure: %#lx: non anonymous thp\n", pfn); else @@ -1126,9 +1126,7 @@ int memory_failure(unsigned long pfn, in put_hwpoison_page(p); return -EBUSY; } - unlock_page(hpage); - get_hwpoison_page(p); - put_hwpoison_page(hpage); + unlock_page(p); VM_BUG_ON_PAGE(!page_count(p), p); hpage = compound_head(p); } Patches currently in stable-queue which might be from n-horiguchi@xxxxxxxxxxxxx are queue-4.8/mm-hwpoison-fix-thp-split-handling-in-memory_failure.patch queue-4.8/mm-hugetlb-fix-huge-page-reservation-leak-in-private-mapping-error-paths.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html