From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753682AbaBLIgR (ORCPT ); Wed, 12 Feb 2014 03:36:17 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50099 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751881AbaBLINw (ORCPT ); Wed, 12 Feb 2014 03:13:52 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Naoya Horiguchi" , "Linus Torvalds" , "Jianguo Wu" Date: Wed, 12 Feb 2014 08:10:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 20/79] mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully In-Reply-To: X-SA-Exim-Connect-IP: 91.84.160.45 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.55-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jianguo Wu commit a49ecbcd7b0d5a1cda7d60e03df402dd0ef76ac8 upstream. After a successful hugetlb page migration by soft offline, the source page will either be freed into hugepage_freelists or buddy(over-commit page). If page is in buddy, page_hstate(page) will be NULL. It will hit a NULL pointer dereference in dequeue_hwpoisoned_huge_page(). BUG: unable to handle kernel NULL pointer dereference at 0000000000000058 IP: [] dequeue_hwpoisoned_huge_page+0x131/0x1d0 PGD c23762067 PUD c24be2067 PMD 0 Oops: 0000 [#1] SMP So check PageHuge(page) after call migrate_pages() successfully. Signed-off-by: Jianguo Wu Tested-by: Naoya Horiguchi Reviewed-by: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [wujg: backport to 3.4: - adjust context - s/num_poisoned_pages/mce_bad_pages/] Signed-off-by: Ben Hutchings --- mm/memory-failure.c | 16 ++++++++++++---- 1 files changed, 12 insertions(+), 4 deletions(-) --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1441,10 +1441,18 @@ static int soft_offline_huge_page(struct return ret; } done: - if (!PageHWPoison(hpage)) - atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages); - set_page_hwpoison_huge_page(hpage); - dequeue_hwpoisoned_huge_page(hpage); + /* overcommit hugetlb page will be freed to buddy */ + if (PageHuge(hpage)) { + if (!PageHWPoison(hpage)) + atomic_long_add(1 << compound_trans_order(hpage), + &mce_bad_pages); + set_page_hwpoison_huge_page(hpage); + dequeue_hwpoisoned_huge_page(hpage); + } else { + SetPageHWPoison(page); + atomic_long_inc(&mce_bad_pages); + } + /* keep elevated page count for bad page */ return ret; }