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 42227C001B0 for ; Mon, 14 Aug 2023 07:55:12 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6C7698D0002; Mon, 14 Aug 2023 03:55:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 677038D0001; Mon, 14 Aug 2023 03:55:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 53F908D0002; Mon, 14 Aug 2023 03:55:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 44C6C8D0001 for ; Mon, 14 Aug 2023 03:55:11 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 0D4A7B200B for ; Mon, 14 Aug 2023 07:55:11 +0000 (UTC) X-FDA: 81121949622.08.F603535 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf18.hostedemail.com (Postfix) with ESMTP id ADD6B1C0006 for ; Mon, 14 Aug 2023 07:55:08 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=HFqD4mv4; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf18.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1691999708; h=from:from:sender: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:dkim-signature; bh=P7/j61t4D/5jBK6eYpwonDi3AuimXp4+GahooloEebQ=; b=R+n48Oa50lDpBbENZViNaylOacRxl1VEASixo8KHQZGre5EjakePfErUVagyQOI+0Af1fu 3P/YZIpjGtAqJz73o7spiB3lR0/hIq1YVifCJjoQ6lFRIBPlI0gbNDwMSIxBg0fOpEIY5G lXymPbzn9lsLcsI9qaLvSjuGxh+cM64= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=HFqD4mv4; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf18.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1691999708; a=rsa-sha256; cv=none; b=1JxEHqkyPc6omo/raaNDzOqjvx+y4cH/yXKJ7LfiOMYAtYhffeQAA8h55tOn1Dl881gpwm F8HfEaelPH4Om5PhhG3w0CmH2BfiyQnBVQjkhGXe51gLpu+Oj/GG3Fv6OuKCuKQWobX1FK P6zi+FieHDSaK7mfuWRpeC900kRAnNg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691999707; 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=P7/j61t4D/5jBK6eYpwonDi3AuimXp4+GahooloEebQ=; b=HFqD4mv4ryTnQlM864dzPayH7AtU9yrtseOvbyEuEY7OyyJKY7IleMTG0CxNLaRchFNuxQ nmnBXnGq0T4vyJG027G3bwd8SYY/CjU3n5ZOMZlbxELqygA1pxLMfaeObs/oOvIhEBUKcm 0xbXOdu6hpnH5dPLmGVwlKQsY1yHWrY= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-367-fdDWEERTN4-mH3PXrM7Bzw-1; Mon, 14 Aug 2023 03:55:06 -0400 X-MC-Unique: fdDWEERTN4-mH3PXrM7Bzw-1 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-31400956ce8so2219260f8f.3 for ; Mon, 14 Aug 2023 00:55:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691999705; x=1692604505; h=content-transfer-encoding:in-reply-to:subject:organization:from :references:cc:to:content-language:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=P7/j61t4D/5jBK6eYpwonDi3AuimXp4+GahooloEebQ=; b=d+BqjUfcO1q/fJSoHQEmYriiFBSqcwqx059RLvn+yYxR8JSkwdW2HSMEx+OeGWLN03 NNC487IR/DpyFHFIeKvRu3T7wOHmkoyREa0e4CGkj/44uNPtT1HYE4oqNEfPC3OCyCPj dcyvH+DxjefuNKu6xtrHFtN+/MfsGBChfU1vxoV1rv3cX1BU4rOb0e2J8twqaPM4l19p 2N89w+ea+G4cMF1EH4nbM0C6Vc2VEkQlwILaSmLQqh1K5n1BspZTLU12VEezyG+JXPSZ YYqf6s7GCJAgGo8vbBf7cZ7EHKXfTajp1VA6kep3RzfWfOCmxUcAEEP/Qx2rbCZJ6vjc hSBQ== X-Gm-Message-State: AOJu0YwC2vJPdyJKEvoVFhAhaEXw1iuNep8JvybCuemznPoeilnlaytm F63ubbdguth2JO8ZN6fPEj2sCxE4BnKxuH6oPDJHmdbjq+bcY02+NzXNjVRsHUWVJBqFMrV5F9u GmP2yMGn2lW8= X-Received: by 2002:a05:6000:100d:b0:314:475:bc47 with SMTP id a13-20020a056000100d00b003140475bc47mr5631615wrx.69.1691999705288; Mon, 14 Aug 2023 00:55:05 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHjVn4+pfyZBdF8li8OulmsCl0dFZ7840nZK9+9x0/pdi4H0k1F/VHRwA/pirI89TgpASHrUQ== X-Received: by 2002:a05:6000:100d:b0:314:475:bc47 with SMTP id a13-20020a056000100d00b003140475bc47mr5631601wrx.69.1691999704917; Mon, 14 Aug 2023 00:55:04 -0700 (PDT) Received: from ?IPV6:2003:d8:2f2b:d900:2d94:8433:b532:3418? (p200300d82f2bd9002d948433b5323418.dip0.t-ipconnect.de. [2003:d8:2f2b:d900:2d94:8433:b532:3418]) by smtp.gmail.com with ESMTPSA id o10-20020a5d684a000000b0031758e7ba6dsm13532656wrw.40.2023.08.14.00.55.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 14 Aug 2023 00:55:04 -0700 (PDT) Message-ID: <00dd353b-e5aa-69fb-6b52-cb59028ea90a@redhat.com> Date: Mon, 14 Aug 2023 09:55:03 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 To: Mateusz Guzik , linux-kernel@vger.kernel.org Cc: torvalds@linux-foundation.org, brauner@kernel.org, ebiederm@xmission.com, akpm@linux-foundation.org, linux-mm@kvack.org, koct9i@gmail.com, oleg@redhat.com, dave@stgolabs.net References: <20230813123333.1705833-1-mjguzik@gmail.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] kernel/fork: stop playing lockless games for exe_file replacement In-Reply-To: <20230813123333.1705833-1-mjguzik@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: ADD6B1C0006 X-Stat-Signature: a7ad7qcyr3oa6c9sz8rsrj7gbxqoieqb X-HE-Tag: 1691999708-592104 X-HE-Meta: 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 W16ZzvX6 F3Y0VPt9bCu4RpEInKmsBc6vXxNt/PzCWPTfdjVGpotMn+40Wk1M+IwMqRxX/FuSD6wKv3pIxL0zBLW1+U5iqt78UEn8DnZ2XcftyEaVzJMm69IznBttuDDjQ/O70jQQ/6HOOw1jWeYymASznQkXpyB8PYZaGN+hQFc43q4RQt+eYoho0RPiIWo6Sq+8HnWl/Ak6SlYyq1iMHZVwIyY5aEws9HKZ54n3B8JjYOj+Odu4kfRgNdSw9cTdhOUgSC58Mm9fG/hNvECtnC+2NygWgbWIqZYpvXDym/jAFhZJEl2oHKsyFoBENFrQbcIdvQ3GTSzIuzCyKaizwEHHD94/WTpIylc+so6ZVxZMqHBfV7xyrVTNsEozbMqUtCmlwbEtMU26TIa/i9D4wg8j2nrIUWxZp2tzz8xYoubJ3Dn7nTkRDFxzkuis0Ozf5ANHRtCUypC2XE/HeGAkOL/918AuCdg3adP903t8DLg3ru/64zerMCCDzigK492ibJSPerjcIWaYvpcg+pWAdMC6e5++9kux49iQcBsI72nWP2/J3f1hylTZndh27/r25RfeqQYCaNfFN X-Bogosity: Ham, tests=bogofilter, spamicity=0.000639, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 13.08.23 14:33, Mateusz Guzik wrote: > xchg originated in 6e399cd144d8 ("prctl: avoid using mmap_sem for > exe_file serialization"). While the commit message does not explain > *why* the change, clearly the intent was to use mmap_sem less in this > codepath. I found the original submission [1] which ultimately claims it > cleans things up. More details are apparently in v1 of that patch: https://lore.kernel.org/lkml/1424979417.10344.14.camel@stgolabs.net/ Regarding your patch: adding more mmap_write_lock() where avoidable, I'm not so sure. Your patch doesn't look (to me) like it is removing a lot of complexity. -- Cheers, David / dhildenb