From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f43.google.com (mail-pb0-f43.google.com [209.85.160.43]) by kanga.kvack.org (Postfix) with ESMTP id 6B7646B0035 for ; Thu, 12 Dec 2013 22:11:01 -0500 (EST) Received: by mail-pb0-f43.google.com with SMTP id rq2so1706539pbb.2 for ; Thu, 12 Dec 2013 19:11:01 -0800 (PST) Received: from szxga02-in.huawei.com (szxga02-in.huawei.com. [119.145.14.65]) by mx.google.com with ESMTPS id wm3si392356pab.107.2013.12.12.19.10.55 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 12 Dec 2013 19:11:00 -0800 (PST) Message-ID: <52AA7A40.2030106@huawei.com> Date: Fri, 13 Dec 2013 11:08:48 +0800 From: Jianguo Wu MIME-Version: 1.0 Subject: Re: [PATCH v2] mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully References: <52AA5E60.3090207@huawei.com> <1386901949-fkz2l9bl-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1386901949-fkz2l9bl-mutt-n-horiguchi@ah.jp.nec.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi 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 Hi, On 2013/12/13 10:32, Naoya Horiguchi wrote: > 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? > Oh, yes, we should only poison the error raw page. I will resend a new version. Thanks, Jianguo Wu > 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