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 1DCCED75E25 for ; Fri, 22 Nov 2024 11:21:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 888636B00B1; Fri, 22 Nov 2024 06:21:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8386F6B00BB; Fri, 22 Nov 2024 06:21:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63BB16B00BC; Fri, 22 Nov 2024 06:21:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 42C8A6B00B1 for ; Fri, 22 Nov 2024 06:21:51 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id C096E12123B for ; Fri, 22 Nov 2024 11:21:50 +0000 (UTC) X-FDA: 82813488744.08.23252CF Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf28.hostedemail.com (Postfix) with ESMTP id C9B68C0011 for ; Fri, 22 Nov 2024 11:20:49 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eWMlBDaT; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf28.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=1732274371; a=rsa-sha256; cv=none; b=u71TcyS5bXw8tCu2xXAZq18ShpqAOzA3pFq9yqtq4QI5l/VLshrT5p1xXVespuOBTlThDv SmFDrWfqgv4iRtndWX/O27bDh/04/vVruD6UP7dZIECLbwMmEnGdkIkbuzcLkhg2RX+evJ gkKI6E5fn1znnzkCJQsce6VO7dMwSuI= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=eWMlBDaT; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf28.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=1732274371; 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=r9Lf9NEh1Wx+KLFWKDJTwrbwUrVCdsepgIGg/rI8pXo=; b=6z7WwRaujIQWwHj4DIe5cS9cbZi3IGU7kc2DH1zoHHf1j5G9FAA0KPfLYUW+3ModFrfGYW Z8F4GZ4tKId3T/yWLSbDCjSdDD/Lj7wk+49Su1gxaLwUwZUd/2eblEVpEw9sVV1B2XAJvC oQDUlUpZuJx4urKKd61DDTdIhUaoeR4= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1732274507; 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:autocrypt:autocrypt; bh=r9Lf9NEh1Wx+KLFWKDJTwrbwUrVCdsepgIGg/rI8pXo=; b=eWMlBDaToZr8K1N2kRdTqjo8RBiJJNw28arJ5nU+9Y5Z5D7pCrYVUFLiFBmHF5vJXeB4gR jPw4v7e31eUI7qa8maLhgQ4KlI7tCC7ES2jpmBGwH+D09Q7vKawrAhK2EAlSqFjGzWqbzR llpHIgET/4B68cviAVYRTOLAKtvYrmo= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-445-hSRJzyVePNafmoFsKvyIXA-1; Fri, 22 Nov 2024 06:21:44 -0500 X-MC-Unique: hSRJzyVePNafmoFsKvyIXA-1 X-Mimecast-MFC-AGG-ID: hSRJzyVePNafmoFsKvyIXA Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-432d9b8503cso16131635e9.0 for ; Fri, 22 Nov 2024 03:21:44 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732274503; x=1732879303; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=r9Lf9NEh1Wx+KLFWKDJTwrbwUrVCdsepgIGg/rI8pXo=; b=wte0C7DomyJugGal6YovlDK0pI+8goIvGe/ResIeyjmgoASlrYLA12HX4TW0L5nZCA DDjDtsWO3OlrLZOn7nIMQAFMrOI32PaB0ROIT6L+Ac14znpiLAnjSlRslW0inTwHGwpb 7u6HSHeaMnMAr9o9MFvNWVukzmOqlEHqk33Yt9yeCUIBSDVAqkrVvK2yIvyhwu6QSK4i Z0QpxYUbJU4zqKC0GyjunI7cg1lJr/AzJlaJgl9VG7LJE/ATuWXko+iCshAFavxK69L5 rLMbvPXbB8BwzpFb4UXu/8HJy/ZR2qoJ/XNnvVj657ffP7E4EwusDbRXW6MQkd6d7wv4 7CcQ== X-Forwarded-Encrypted: i=1; AJvYcCU4G64SGQ5ctqlkeYA5unVQ09qxqD/DpBbuVMRg7pSul7jmBLVEmXD47BKiFD6qlkRS9umWPHyKrg==@kvack.org X-Gm-Message-State: AOJu0Yxy2TxSibd5LbXf4/9IsYRlZ2eBlLjmbjmI8aPkqlrbrSNrWRmm 6qC3g0eNXiYTbER0A9Wi4HeHKW4afe/2WEiJOUfcJgkm/0eWvANpyJmFbKuPKZzcFmM+6XQkEbt h6PkKjwPmUZuHkvLR35A6+UzndBiuZ3vi5boz5nHhYtYhWD/1 X-Gm-Gg: ASbGncsxAp4utNT/p2xNSQUigHFWWIpZH2NnA/9eaWd7fFH6hPKzBkhFxWCpwu+ytk9 O6TAVjJzFqSmzhrz57zbYQ/HjpMRkW/NC2t0jDQBW8CkA4Vv8UoE+lAV8PYKugFf1m65y8aFF7d YPupgkr46OLb+HsR0dzyJUaGyVcSwTsVkcdehGKDFuZyIMfbwB03Za/egFAVGWJeH080mmjqtZW B4jE7Cgbu/zOGvxuE9L3LXDmVPmyA7WEbZubVFU1/NdMYrkvD33saAjqEVArbDc9sv2VKW+Nj0F XYeJpQ/zGCGA4MT9kqLTGKBQVZ6sR1YfwJtJ1I+oTcrOmnkU+tRGthsfzYZVjkdKRIh4SnGLgfs = X-Received: by 2002:a05:600c:a296:b0:42c:b826:a26c with SMTP id 5b1f17b1804b1-433c5ca2428mr56849385e9.8.1732274503262; Fri, 22 Nov 2024 03:21:43 -0800 (PST) X-Google-Smtp-Source: AGHT+IH2+3otb3BDknrAK8yb894tbDvw/KXdTTwseaY15YXhYSr7ICKAhguNlMjvBKBCnMg3L+0gRQ== X-Received: by 2002:a05:600c:a296:b0:42c:b826:a26c with SMTP id 5b1f17b1804b1-433c5ca2428mr56849055e9.8.1732274502927; Fri, 22 Nov 2024 03:21:42 -0800 (PST) Received: from ?IPV6:2003:cb:c70b:7a00:9ccd:493:d8e2:9ac8? (p200300cbc70b7a009ccd0493d8e29ac8.dip0.t-ipconnect.de. [2003:cb:c70b:7a00:9ccd:493:d8e2:9ac8]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3825fad6730sm2173502f8f.9.2024.11.22.03.21.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Nov 2024 03:21:42 -0800 (PST) Message-ID: Date: Fri, 22 Nov 2024 12:21:41 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] seqlock: add raw_seqcount_try_begin To: Peter Zijlstra Cc: Suren Baghdasaryan , akpm@linux-foundation.org, andrii@kernel.org, jannh@google.com, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, mhocko@kernel.org, shakeel.butt@linux.dev, hannes@cmpxchg.org, willy@infradead.org, brauner@kernel.org, oleg@redhat.com, arnd@arndb.de, richard.weiyang@gmail.com, zhangpeng.00@bytedance.com, linmiaohe@huawei.com, viro@zeniv.linux.org.uk, hca@linux.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20241121162826.987947-1-surenb@google.com> <46aa36f0-64a6-4aee-8134-0ec93f62e59c@redhat.com> <20241122111914.GS24774@noisy.programming.kicks-ass.net> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20241122111914.GS24774@noisy.programming.kicks-ass.net> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: -AjsM6EsEymp8xCl2gUy2AYVuXjN8h3PYxADO9g6WS0_1732274503 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: C9B68C0011 X-Stat-Signature: jejwd8bds4tcwi7wt95sjpibpf3uq7aw X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1732274449-507727 X-HE-Meta: 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 7fMw9Zrn 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 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: List-Subscribe: List-Unsubscribe: On 22.11.24 12:19, Peter Zijlstra wrote: > On Fri, Nov 22, 2024 at 12:10:29PM +0100, David Hildenbrand wrote: > >> In gup_fast(), we simply do >> >> seq = raw_read_seqcount(¤t->mm->write_protect_seq); >> if (seq & 1) >> return 0; >> >> Should we be using that there as well? >> >> if (!raw_seqcount_try_begin(¤t->mm->write_protect_seqs, seq)) >> return 0; > > Might as well. A quick grep doesn't find me another instance of this > pattern, but does find me something 'funny' in net/netfilter/x_tables.c. > Let's pretend I didn't see that for now ... *sigh* :) I'm also not 100% sure about barriers in gup_fast() around the raw_seqcount .... and I'm pretending I didn't see any of that as well ... > > Want me to stick a patch like this on, or do you want to do that later, > when the dust has settled? Feel free to add a patch to just change that as well, it's an easy change. For this patch Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb