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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6F81C48BDF for ; Tue, 15 Jun 2021 12:42:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 447E561464 for ; Tue, 15 Jun 2021 12:42:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 447E561464 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C8EBE6B0036; Tue, 15 Jun 2021 08:42:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C63DE6B006E; Tue, 15 Jun 2021 08:42:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B2BEB6B0070; Tue, 15 Jun 2021 08:42:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0025.hostedemail.com [216.40.44.25]) by kanga.kvack.org (Postfix) with ESMTP id 8061C6B0036 for ; Tue, 15 Jun 2021 08:42:30 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 1D78E181AEF0B for ; Tue, 15 Jun 2021 12:42:30 +0000 (UTC) X-FDA: 78255921660.11.0E44C28 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf10.hostedemail.com (Postfix) with ESMTP id 67F1641AD7B6 for ; Tue, 15 Jun 2021 12:42:20 +0000 (UTC) Received: from dggeme703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4G47Dd5q18zZdc6; Tue, 15 Jun 2021 20:39:29 +0800 (CST) Received: from [10.174.176.146] (10.174.176.146) by dggeme703-chm.china.huawei.com (10.1.199.99) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Tue, 15 Jun 2021 20:42:23 +0800 Subject: Re: [PATCH v1 1/6] mm/hwpoison: mf_mutex for soft offline and unpoison To: Naoya Horiguchi CC: Andrew Morton , David Hildenbrand , Oscar Salvador , Michal Hocko , Ding Hui , Tony Luck , Aneesh Kumar K.V , Naoya Horiguchi , , Linux-MM References: <20210614021212.223326-1-nao.horiguchi@gmail.com> <20210614021212.223326-2-nao.horiguchi@gmail.com> From: Miaohe Lin Message-ID: Date: Tue, 15 Jun 2021 20:42:23 +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: <20210614021212.223326-2-nao.horiguchi@gmail.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.146] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggeme703-chm.china.huawei.com (10.1.199.99) X-CFilter-Loop: Reflected Authentication-Results: imf10.hostedemail.com; dkim=none; spf=pass (imf10.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=none) header.from=huawei.com X-Stat-Signature: ajitr5qhofikmos8939td1oxm5jrp6do X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 67F1641AD7B6 X-HE-Tag: 1623760940-65979 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: Hi: On 2021/6/14 10:12, Naoya Horiguchi wrote: > From: Naoya Horiguchi > > Originally mf_mutex is introduced to serialize multiple MCE events, but > it's also helpful to exclude races among soft_offline_page() and > unpoison_memory(). So apply mf_mutex to them. > When I was investigating the memory-failure code, I realized these possible races too. It's very kind of you to fix these races! Many thanks! > Signed-off-by: Naoya Horiguchi > --- > mm/memory-failure.c | 26 ++++++++++++++++++-------- > 1 file changed, 18 insertions(+), 8 deletions(-) > > diff --git v5.13-rc5/mm/memory-failure.c v5.13-rc5_patched/mm/memory-failure.c > index ae30fd6d575a..280eb6d6dd15 100644 > --- v5.13-rc5/mm/memory-failure.c > +++ v5.13-rc5_patched/mm/memory-failure.c > @@ -1583,6 +1583,8 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, > return rc; > } > > +static DEFINE_MUTEX(mf_mutex); > + > /** > * memory_failure - Handle memory failure of a page. > * @pfn: Page Number of the corrupted page > @@ -1609,7 +1611,6 @@ int memory_failure(unsigned long pfn, int flags) > int res = 0; > unsigned long page_flags; > bool retry = true; > - static DEFINE_MUTEX(mf_mutex); > > if (!sysctl_memory_failure_recovery) > panic("Memory failure on page %lx", pfn); > @@ -1918,6 +1919,7 @@ int unpoison_memory(unsigned long pfn) > struct page *page; > struct page *p; > int freeit = 0; > + int ret = 0; > unsigned long flags = 0; > static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL, > DEFAULT_RATELIMIT_BURST); > @@ -1928,28 +1930,30 @@ int unpoison_memory(unsigned long pfn) > p = pfn_to_page(pfn); > page = compound_head(p); > > + mutex_lock(&mf_mutex); > + > if (!PageHWPoison(p)) { > unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n", > pfn, &unpoison_rs); > - return 0; > + goto unlock_mutex; > } > > if (page_count(page) > 1) { > unpoison_pr_info("Unpoison: Someone grabs the hwpoison page %#lx\n", > pfn, &unpoison_rs); > - return 0; > + goto unlock_mutex; > } > > if (page_mapped(page)) { > unpoison_pr_info("Unpoison: Someone maps the hwpoison page %#lx\n", > pfn, &unpoison_rs); > - return 0; > + goto unlock_mutex; > } > > if (page_mapping(page)) { > unpoison_pr_info("Unpoison: the hwpoison page has non-NULL mapping %#lx\n", > pfn, &unpoison_rs); > - return 0; > + goto unlock_mutex; > } > > /* > @@ -1960,7 +1964,7 @@ int unpoison_memory(unsigned long pfn) > if (!PageHuge(page) && PageTransHuge(page)) { > unpoison_pr_info("Unpoison: Memory failure is now running on %#lx\n", > pfn, &unpoison_rs); > - return 0; > + goto unlock_mutex; > } > Maybe it's more appropriate to start mutex_lock(&mf_mutex) here? I think these races start here. > if (!get_hwpoison_page(p, flags)) { > @@ -1968,7 +1972,7 @@ int unpoison_memory(unsigned long pfn) > num_poisoned_pages_dec(); > unpoison_pr_info("Unpoison: Software-unpoisoned free page %#lx\n", > pfn, &unpoison_rs); > - return 0; > + goto unlock_mutex; > } > > lock_page(page); > @@ -1990,7 +1994,9 @@ int unpoison_memory(unsigned long pfn) > if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) > put_page(page); > > - return 0; > +unlock_mutex: > + mutex_unlock(&mf_mutex); > + return ret; > } > EXPORT_SYMBOL(unpoison_memory); > > @@ -2171,6 +2177,8 @@ int soft_offline_page(unsigned long pfn, int flags) > return -EIO; > } > > + mutex_lock(&mf_mutex); > + > if (PageHWPoison(page)) { > pr_info("%s: %#lx page already poisoned\n", __func__, pfn); > put_ref_page(ref_page); > @@ -2194,5 +2202,7 @@ int soft_offline_page(unsigned long pfn, int flags) > __func__, pfn, page->flags, &page->flags); > } > > + mutex_unlock(&mf_mutex); > + > return ret; > } >