From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5083C433FE for ; Mon, 14 Mar 2022 01:51:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D51608D0002; Sun, 13 Mar 2022 21:51:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CE5C58D0001; Sun, 13 Mar 2022 21:51:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B9FCD8D0002; Sun, 13 Mar 2022 21:51:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id A776E8D0001 for ; Sun, 13 Mar 2022 21:51:20 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 65E80808AB for ; Mon, 14 Mar 2022 01:51:20 +0000 (UTC) X-FDA: 79241314320.04.2C859CC Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf19.hostedemail.com (Postfix) with ESMTP id 2F5A61A0028 for ; Mon, 14 Mar 2022 01:51:19 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KGzxT0WnwzfYyq; Mon, 14 Mar 2022 09:49:49 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Mon, 14 Mar 2022 09:51:14 +0800 Subject: Re: [PATCH v2 1/3] mm/memory-failure.c: fix race with changing page compound again To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= CC: "akpm@linux-foundation.org" , "tony.luck@intel.com" , "bp@alien8.de" , "mike.kravetz@oracle.com" , "shy828301@gmail.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "linux-edac@vger.kernel.org" References: <20220312074613.4798-1-linmiaohe@huawei.com> <20220312074613.4798-2-linmiaohe@huawei.com> <20220313234100.GA3010057@hori.linux.bs1.fc.nec.co.jp> From: Miaohe Lin Message-ID: <86d13611-dcd2-7c1b-eed8-28f9349f6201@huawei.com> Date: Mon, 14 Mar 2022 09:51:14 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220313234100.GA3010057@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspam-User: Authentication-Results: imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2F5A61A0028 X-Stat-Signature: 6xdzcmxtitsr3tdhttu9fzuwsik91yxd X-HE-Tag: 1647222679-604789 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/3/14 7:41, HORIGUCHI NAOYA(堀口 直也) wrote: > On Sat, Mar 12, 2022 at 03:46:11PM +0800, Miaohe Lin wrote: >> There is a race window where we got the compound_head, the hugetlb page >> could be freed to buddy, or even changed to another compound page just >> before we try to get hwpoison page. Think about the below race window: >> CPU 1 CPU 2 >> memory_failure_hugetlb >> struct page *head = compound_head(p); >> hugetlb page might be freed to >> buddy, or even changed to another >> compound page. >> >> get_hwpoison_page -- page is not what we want now... >> >> If this race happens, just bail out. Also MF_MSG_DIFFERENT_PAGE_SIZE is >> introduced to record this event. >> >> Signed-off-by: Miaohe Lin >> --- >> include/linux/mm.h | 1 + >> include/ras/ras_event.h | 1 + >> mm/memory-failure.c | 12 ++++++++++++ >> 3 files changed, 14 insertions(+) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index c9bada4096ac..ef98cff2b253 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -3253,6 +3253,7 @@ enum mf_action_page_type { >> MF_MSG_BUDDY, >> MF_MSG_DAX, >> MF_MSG_UNSPLIT_THP, >> + MF_MSG_DIFFERENT_PAGE_SIZE, >> MF_MSG_UNKNOWN, >> }; >> >> diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h >> index d0337a41141c..1e694fd239b9 100644 >> --- a/include/ras/ras_event.h >> +++ b/include/ras/ras_event.h >> @@ -374,6 +374,7 @@ TRACE_EVENT(aer_event, >> EM ( MF_MSG_BUDDY, "free buddy page" ) \ >> EM ( MF_MSG_DAX, "dax page" ) \ >> EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" ) \ >> + EM ( MF_MSG_DIFFERENT_PAGE_SIZE, "different page size" ) \ >> EMe ( MF_MSG_UNKNOWN, "unknown page" ) >> >> /* >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index 5444a8ef4867..dabecd87ad3f 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -733,6 +733,7 @@ static const char * const action_page_types[] = { >> [MF_MSG_BUDDY] = "free buddy page", >> [MF_MSG_DAX] = "dax page", >> [MF_MSG_UNSPLIT_THP] = "unsplit thp", >> + [MF_MSG_DIFFERENT_PAGE_SIZE] = "different page size", >> [MF_MSG_UNKNOWN] = "unknown page", >> }; >> >> @@ -1534,6 +1535,17 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) >> } >> >> lock_page(head); >> + >> + /** > > This comment section starting with '/**' is considered as kernel-doc comment, > maybe that's not expected because it just describes an implementation detail. > So normal comment section with '/*' would be better. > I see. Will change to use "/*". > Otherwise, looks good to me. > > Acked-by: Naoya Horiguchi Many thanks for review and comment. > >> + * The page could have changed compound pages due to race window. >> + * If this happens just bail out. >> + */ >> + if (!PageHuge(p) || compound_head(p) != head) { >> + action_result(pfn, MF_MSG_DIFFERENT_PAGE_SIZE, MF_IGNORED); >> + res = -EBUSY; >> + goto out; >> + } >> + >> page_flags = head->flags; >> >> if (hwpoison_filter(p)) { >> -- >> 2.23.0