From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751703Ab3LMA61 (ORCPT ); Thu, 12 Dec 2013 19:58:27 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:45044 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751562Ab3LMA6Z (ORCPT ); Thu, 12 Dec 2013 19:58:25 -0500 Message-ID: <52AA5B4E.2050601@huawei.com> Date: Fri, 13 Dec 2013 08:56:46 +0800 From: Jianguo Wu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Naoya Horiguchi CC: Andrew Morton , Andi Kleen , Mel Gorman , Wanpeng Li , qiuxishi , Hanjun Guo , , , Subject: Re: [PATCH] mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfull References: <52A9B69D.50307@huawei.com> <1386869964-gyz86343-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1386869964-gyz86343-mutt-n-horiguchi@ah.jp.nec.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.74.216] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Naoya, On 2013/12/13 1:39, Naoya Horiguchi wrote: > (Cced: Chen Gong) > > I confirmed that this patch fixes the reported bug. > And I'll send a test patch for mce-test later privately. > > Tested-by: Naoya Horiguchi > > Jianguo, could you put "Cc: stable@vger.kernel.org" > in patch description? > And please fix a typo in subject line. > OK, thanks for your tested! Thanks, Jianguo Wu > Thanks, > Naoya Horiguchi > > On Thu, Dec 12, 2013 at 09:14:05PM +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() 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 >> > > . >