From patchwork Mon Apr 22 12:38:33 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 238880 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id B03FF2C0172 for ; Tue, 23 Apr 2013 20:54:46 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UUarp-0000X3-9M; Tue, 23 Apr 2013 10:54:33 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UUG0z-0000xT-Cr for kernel-team@lists.ubuntu.com; Mon, 22 Apr 2013 12:38:37 +0000 Received: from bl20-133-161.dsl.telepac.pt ([2.81.133.161] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UUG0w-0003Oy-F6; Mon, 22 Apr 2013 12:38:34 +0000 From: Luis Henriques To: Naoya Horiguchi Subject: [ 3.5.y.z extended stable ] Patch "hugetlbfs: add swap entry check in follow_hugetlb_page()" has been added to staging queue Date: Mon, 22 Apr 2013 13:38:33 +0100 Message-Id: <1366634313-16875-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 X-Extended-Stable: 3.5 X-Mailman-Approved-At: Tue, 23 Apr 2013 10:54:33 +0000 Cc: Rik van Riel , kernel-team@lists.ubuntu.com, Michal Hocko , HATAYAMA Daisuke , KOSAKI Motohiro , David Rientjes , Andrew Morton , Linus Torvalds X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled hugetlbfs: add swap entry check in follow_hugetlb_page() to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 62709d30044278c7f850b13afd02254fee2beb6a Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Wed, 17 Apr 2013 15:58:30 -0700 Subject: [PATCH] hugetlbfs: add swap entry check in follow_hugetlb_page() commit 9cc3a5bd40067b9a0fbd49199d0780463fc2140f upstream. With applying the previous patch "hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)" to reenable hugepage coredump, if a memory error happens on a hugepage and the affected processes try to access the error hugepage, we hit VM_BUG_ON(atomic_read(&page->_count) <= 0) in get_page(). The reason for this bug is that coredump-related code doesn't recognise "hugepage hwpoison entry" with which a pmd entry is replaced when a memory error occurs on a hugepage. In other words, physical address information is stored in different bit layout between hugepage hwpoison entry and pmd entry, so follow_hugetlb_page() which is called in get_dump_page() returns a wrong page from a given address. The expected behavior is like this: absent is_swap_pte FOLL_DUMP Expected behavior ------------------------------------------------------------------- true false false hugetlb_fault false true false hugetlb_fault false false false return page true false true skip page (to avoid allocation) false true true hugetlb_fault false false true return page With this patch, we can call hugetlb_fault() and take proper actions (we wait for migration entries, fail with VM_FAULT_HWPOISON_LARGE for hwpoisoned entries,) and as the result we can dump all hugepages except for hwpoisoned ones. Signed-off-by: Naoya Horiguchi Cc: Rik van Riel Acked-by: Michal Hocko Cc: HATAYAMA Daisuke Acked-by: KOSAKI Motohiro Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- mm/hugetlb.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) -- 1.8.1.2 diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f30e463..74b8327 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2907,7 +2907,17 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, break; } - if (absent || + /* + * We need call hugetlb_fault for both hugepages under migration + * (in which case hugetlb_fault waits for the migration,) and + * hwpoisoned hugepages (in which case we need to prevent the + * caller from accessing to them.) In order to do this, we use + * here is_swap_pte instead of is_hugetlb_entry_migration and + * is_hugetlb_entry_hwpoisoned. This is because it simply covers + * both cases, and because we can't follow correct pages + * directly from any kind of swap entries. + */ + if (absent || is_swap_pte(huge_ptep_get(pte)) || ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) { int ret;