From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f51.google.com (mail-pb0-f51.google.com [209.85.160.51]) by kanga.kvack.org (Postfix) with ESMTP id B6CC76B0037 for ; Thu, 12 Dec 2013 08:14:51 -0500 (EST) Received: by mail-pb0-f51.google.com with SMTP id up15so483094pbc.38 for ; Thu, 12 Dec 2013 05:14:51 -0800 (PST) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com. [119.145.14.64]) by mx.google.com with ESMTPS id q8si16511485pav.289.2013.12.12.05.14.44 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 12 Dec 2013 05:14:50 -0800 (PST) Message-ID: <52A9B69D.50307@huawei.com> Date: Thu, 12 Dec 2013 21:14:05 +0800 From: Jianguo Wu MIME-Version: 1.0 Subject: [PATCH] mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfull Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Andi Kleen , Mel Gorman , Naoya Horiguchi , Wanpeng Li , qiuxishi , Hanjun Guo , linux-mm@kvack.org, linux-kernel@vger.kernel.org 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(). [ 890.677918] BUG: unable to handle kernel NULL pointer dereference at 0000000000000058 [ 890.685741] IP: [] dequeue_hwpoisoned_huge_page+0x131/0x1d0 [ 890.692861] PGD c23762067 PUD c24be2067 PMD 0 [ 890.697314] Oops: 0000 [#1] SMP So check PageHuge(page) after call migrate_pages() successfull. Signed-off-by: Jianguo Wu --- mm/memory-failure.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index b7c1716..e5567f2 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1471,7 +1471,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags) static int soft_offline_huge_page(struct page *page, int flags) { - int ret; + int ret, i; + unsigned long nr_pages; unsigned long pfn = page_to_pfn(page); struct page *hpage = compound_head(page); LIST_HEAD(pagelist); @@ -1489,6 +1490,8 @@ static int soft_offline_huge_page(struct page *page, int flags) } unlock_page(hpage); + nr_pages = 1 << compound_order(hpage); + /* Keep page count to indicate a given hugepage is isolated. */ list_move(&hpage->lru, &pagelist); ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, @@ -1505,10 +1508,16 @@ static int soft_offline_huge_page(struct page *page, int flags) if (ret > 0) ret = -EIO; } else { - set_page_hwpoison_huge_page(hpage); - dequeue_hwpoisoned_huge_page(hpage); - atomic_long_add(1 << compound_order(hpage), - &num_poisoned_pages); + /* over-commit hugetlb page will be freed into buddy */ + if (PageHuge(page)) { + set_page_hwpoison_huge_page(hpage); + dequeue_hwpoisoned_huge_page(hpage); + } else { + for (i = 0; i < nr_pages; i++) + SetPageHWPoison(hpage + i); + } + + atomic_long_add(nr_pages, &num_poisoned_pages); } return ret; } -- 1.8.2.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org