From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f47.google.com (mail-wg0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id 45E006B0035 for ; Thu, 12 Dec 2013 21:32:59 -0500 (EST) Received: by mail-wg0-f47.google.com with SMTP id n12so1263660wgh.2 for ; Thu, 12 Dec 2013 18:32:58 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id yx3si164451wjc.17.2013.12.12.18.32.57 for ; Thu, 12 Dec 2013 18:32:57 -0800 (PST) Date: Thu, 12 Dec 2013 21:32:29 -0500 From: Naoya Horiguchi Message-ID: <1386901949-fkz2l9bl-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <52AA5E60.3090207@huawei.com> References: <52AA5E60.3090207@huawei.com> Subject: Re: [PATCH v2] mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Jianguo Wu Cc: Andrew Morton , Andi Kleen , Mel Gorman , Wanpeng Li , Hanjun Guo , qiuxishi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, gong.chen@linux.intel.com On Fri, Dec 13, 2013 at 09:09:52AM +0800, Jianguo Wu wrote: > 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() successfully. > > Tested-by: Naoya Horiguchi > Cc: stable@vger.kernel.org > 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); > + /* overcommit hugetlb page will be freed to 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); Why don't you set PageHWPoison only on the error raw page instead of the whole error hugepage, or is there some problem of doing so? Thanks, Naoya > + } > + > + 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 > -- 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