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=-12.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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 68AAAC433ED for ; Wed, 5 May 2021 13:18:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E7496613BE for ; Wed, 5 May 2021 13:18:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E7496613BE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 534956B006C; Wed, 5 May 2021 09:18:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4E4476B006E; Wed, 5 May 2021 09:18:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 310136B0070; Wed, 5 May 2021 09:18:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0049.hostedemail.com [216.40.44.49]) by kanga.kvack.org (Postfix) with ESMTP id 14E476B006C for ; Wed, 5 May 2021 09:18:01 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id C1B498249980 for ; Wed, 5 May 2021 13:18:00 +0000 (UTC) X-FDA: 78107230320.11.70523ED Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf19.hostedemail.com (Postfix) with ESMTP id 79E5890009ED for ; Wed, 5 May 2021 13:17:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620220679; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QtrXxKUiAvmqmB6yyp++vsOaAc/bZaOc4BH5ZWRKiJg=; b=Z5AlaUhhf+Dcu5XrzQq1bDEtlvScjQBIKL9pgKHrWd9A6cP0I1n+CAO4wpDRviXb48E94C xgwwDs24vE0DMmwV4E2VyFOIi/X12cuMO4+RBiQtlRK8LaBQrtdbgoh6LwPKIJQ0tLrCfm LGSuyIZeI/s2ib7IqWuggs+YRz3ZCKo= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-153-PlIKN_GfNfycA0ACbuWZpQ-1; Wed, 05 May 2021 09:17:56 -0400 X-MC-Unique: PlIKN_GfNfycA0ACbuWZpQ-1 Received: by mail-wm1-f69.google.com with SMTP id r10-20020a05600c2c4ab029014b601975e1so1421650wmg.0 for ; Wed, 05 May 2021 06:17:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=QtrXxKUiAvmqmB6yyp++vsOaAc/bZaOc4BH5ZWRKiJg=; b=TOvnECU4lOWb1tea+NkVHsdJpFgiW17fbp/k+jcUUQimSGlFoxjAN7ixMSEkB8NKWH eZ+aJRn8IsStkcQlyrwJ+Z6Cjklmc6pSKk1m8vX121Zyx5XvWyoCxL63R1Id2c1nyWa5 dOYt5j6MRM0WCcUvsi3m8a7kzaPK6V8n1/7YmbN7emLejrmGVpIfPkXfGhamn/Lk0CT5 1sX8UjbsnavXG7F54Hr6LGFs4kUpuYx2Eq/AukqB3Q/l9nt/X8tMaYFaWQ/QKYL21I08 YmlSFnn99JAYJTtHbwzKmcUPwOeDO7jF8QA1chiVJtkKW4FdIgQzjBtdSaMk/quGInAv ISPg== X-Gm-Message-State: AOAM533gj1DX4hroWCieIcO8qZ7iuebDmZ8pxpEl+mHfoyX4Yk8zA1iD ez3fQ2b1+OCjybRaJR/LsSYcCwIWU2p/XKvSMbv6aZkKuhYD8GeGIyMVHINvofVQE3CtHashKwa pnkHm3s2OJb1lJb14sOYmuzwaGgTkxFK6xzOoPn+mmGOBumWmcUxPX/7W4kI= X-Received: by 2002:a7b:c74d:: with SMTP id w13mr32277718wmk.25.1620220675040; Wed, 05 May 2021 06:17:55 -0700 (PDT) X-Google-Smtp-Source: ABdhPJznzW0sfSsf6GMPNX1ppZVMk3nl9+IxB31SmKuXCFiIEFbzLjLS3W1tcOolWD10Wc36ulvXeg== X-Received: by 2002:a7b:c74d:: with SMTP id w13mr32277671wmk.25.1620220674718; Wed, 05 May 2021 06:17:54 -0700 (PDT) Received: from [192.168.3.132] (p5b0c63bc.dip0.t-ipconnect.de. [91.12.99.188]) by smtp.gmail.com with ESMTPSA id v13sm20005354wrt.65.2021.05.05.06.17.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 May 2021 06:17:54 -0700 (PDT) Subject: Re: [PATCH v1 3/7] mm: rename and move page_is_poisoned() To: Michal Hocko Cc: linux-kernel@vger.kernel.org, Andrew Morton , "Michael S. Tsirkin" , Jason Wang , Alexey Dobriyan , Mike Rapoport , "Matthew Wilcox (Oracle)" , Oscar Salvador , Roman Gushchin , Alex Shi , Steven Price , Mike Kravetz , Aili Yao , Jiri Bohac , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Naoya Horiguchi , linux-hyperv@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20210429122519.15183-1-david@redhat.com> <20210429122519.15183-4-david@redhat.com> From: David Hildenbrand Organization: Red Hat Message-ID: <0710d8d5-2608-aeed-10c7-50a272604d97@redhat.com> Date: Wed, 5 May 2021 15:17:53 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Z5AlaUhh; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf19.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=david@redhat.com X-Stat-Signature: 1pmxtpf1g4dn67imcnezh4etmnotcscm X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 79E5890009ED Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf19; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620220648-812566 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 05.05.21 15:13, Michal Hocko wrote: > On Thu 29-04-21 14:25:15, David Hildenbrand wrote: >> Commit d3378e86d182 ("mm/gup: check page posion status for coredump.") >> introduced page_is_poisoned(), however, v5 [1] of the patch used >> "page_is_hwpoison()" and something went wrong while upstreaming. Rename the >> function and move it to page-flags.h, from where it can be used in other >> -- kcore -- context. >> >> Move the comment to the place where it belongs and simplify. >> >> [1] https://lkml.kernel.org/r/20210322193318.377c9ce9@alex-virtual-machine >> >> Signed-off-by: David Hildenbrand > > I do agree that being explicit about hwpoison is much better. Poisoned > page can be also an unitialized one and I believe this is the reason why > you are bringing that up. I'm bringing it up because I want to reuse that function as state above :) > > But you've made me look at d3378e86d182 and I am wondering whether this > is really a valid patch. First of all it can leak a reference count > AFAICS. Moreover it doesn't really fix anything because the page can be > marked hwpoison right after the check is done. I do not think the race > is feasible to be closed. So shouldn't we rather revert it? I am not sure if we really care about races here that much here? I mean, essentially we are racing with HW breaking asynchronously. Just because we would be synchronizing with SetPageHWPoison() wouldn't mean we can stop HW from breaking. Long story short, this should be good enough for the cases we actually can handle? What am I missing? -- Thanks, David / dhildenb