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 BA7E5C35FFA for ; Wed, 19 Mar 2025 19:46:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3E971280010; Wed, 19 Mar 2025 15:46:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 398CC28000F; Wed, 19 Mar 2025 15:46:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 23A41280010; Wed, 19 Mar 2025 15:46:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 05AC828000F for ; Wed, 19 Mar 2025 15:46:14 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 9C61FA50B6 for ; Wed, 19 Mar 2025 19:46:15 +0000 (UTC) X-FDA: 83239331910.29.74E5542 Received: from mail-qv1-f50.google.com (mail-qv1-f50.google.com [209.85.219.50]) by imf24.hostedemail.com (Postfix) with ESMTP id 4D036180014 for ; Wed, 19 Mar 2025 19:46:13 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=3O7pCY32; spf=pass (imf24.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.219.50 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742413573; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EMGdQd+1GtsqkZyrmcturm7A0b+BWeuqV9nKfwmQHB8=; b=JxOE9vmzbxYm19xTjZDJaOa2YV6OXAg06l/7y5qbXpptaFKPHRNf6qhF6OipKg+bSgNagK yk+K4VTogGErGpCnoe623p6CaXnlbAgr5wSjk8K+SyvcEee+VO3KoZ1HrRd0dmlzcFyePN y8PrAYOn9h7XABFBO8dNm/yTJIsUb5g= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=3O7pCY32; spf=pass (imf24.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.219.50 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742413573; a=rsa-sha256; cv=none; b=SFHwyHDNB2deSmaeJoctcSakwjq9YeIJsg//zHV2aFEAAm4AiUQuqcjXKAmEe7l7uW6cYU rqt4EBGdPXdu0AY+UxuGE/X5NFGEqZOPYJ8uXBsWo0aGRnWvqRTXwkDp1zqRjZvf0WttzN gR2k44t6dINEkugQ2lMCHodhlyv3Hl0= Received: by mail-qv1-f50.google.com with SMTP id 6a1803df08f44-6e86b92d3b0so20066d6.2 for ; Wed, 19 Mar 2025 12:46:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20230601.gappssmtp.com; s=20230601; t=1742413572; x=1743018372; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=EMGdQd+1GtsqkZyrmcturm7A0b+BWeuqV9nKfwmQHB8=; b=3O7pCY32IJMCUuw5q0tW3F+wGHEI4QHOdz0rEYLm0f/4cLhzZKXSSnVN2EyDIwDw6S 37G+O6NbplFM3sDoZSEtp4zG10g6QYX/ZFOfAcqlUWSKUChi75lW1cuRC6WAgk+EHji+ Gi2t9NB52cDSBDsgBy2uNkp4pXrIU4D3PfXbIht/iQ7xfsOuJsIG0p7pKSqQsoEKCrP6 SS8z8Tbmbv4T20q5WFBmtrozI2cThkfI5IAnUWKIoRw/io/X/c+rbvnYqvYLI+YecOyD l1KA+yS8VPw6mshi3Aja2bIJOxfGrN0yDnNDtGwbwGnCTt4SxFUHaadBB/ytS/2zegRV DW/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1742413572; x=1743018372; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=EMGdQd+1GtsqkZyrmcturm7A0b+BWeuqV9nKfwmQHB8=; b=rN8k4nmmSo3PSmbB4FLr6FdJ3Asx4qBJZs09EJ4sPIbyDzK1yfPRnbWHeVJTo6vIG5 L/pjN5w+IsfMa4/xQA+IKunAr659rncL4a8wWZzfrdEYd2vOXXF7vrNa053YZ8hSZpIC AyIByDiH4/x1u9j8ev1rZMr/3x0MT3g19qoGRe155NTT1tNfEVMueFu51gritzZ8gUBc wLTwGzR/EGdXGrS32EPMWlqp3UUh9MW3qQbhIRyQqPYOvoCvZLdNI8av+cDoPAAD8KHA JccJwbH17e7l9p8nFl/c9SezJKGOdjmH3au5qn4s0UDbVGH89YSlJzIBh1YNHm0QRUGd fDnQ== X-Forwarded-Encrypted: i=1; AJvYcCWJIqd7poS5wUnIbfblzBFYIxhJUqC2iytKXZOU2dEbfQ/mOD0dh59p0m/6s0wks2Rj+X4kZWTuKQ==@kvack.org X-Gm-Message-State: AOJu0YyaQKz5QEZWWfz9mGe5Lu92yiMgwcfCMQKENkJPuXhQWkvKI8eC aTRhAwKb3ixNVfoHEoSllDnplSuXDwwtUYCfpMtZ55pTRjWnsndopglT9bvro7I= X-Gm-Gg: ASbGncsrvoI3ZmqnQUFGQ9fkhtOY7PXiDyIg/nb0yYP4tzIRnIpio25mQduFW5soua0 MH9Dl196k3unUtdFyWYt0jA+MHiXLJNsCuEj2gNkQZM15NzMMqk//LrMatZcXqPWvyXbuWGGEQY 7XcegAd2DL1PbML3COK+e4JlbVwzHUDI0bH+tWG1iNpSoWaLHPRQSVao7lWUgx5rk37cVicHnD5 Ncxfp3v7jzU5VIYJNfHdP/QCg+PMk3KN0JDoA2nGwBLg45nvK/81HJiND5kv3INq5AltlETFhZh ovMxZTckqISzY45RlDtjRjWs7JGoxtbRS9N+SJwgh5A= X-Google-Smtp-Source: AGHT+IGBPtC/y//GuXQrmvUuvNI+AJ1VTUL//CIpJG88EeiQgsUx/MStOJniyzmiXVM1kRKKRMEnkw== X-Received: by 2002:ad4:4eae:0:b0:6e8:9dc9:1c03 with SMTP id 6a1803df08f44-6eb293a3360mr70586226d6.21.1742413572115; Wed, 19 Mar 2025 12:46:12 -0700 (PDT) Received: from localhost ([2603:7000:c01:2716:da5e:d3ff:fee7:26e7]) by smtp.gmail.com with UTF8SMTPSA id 6a1803df08f44-6eb036e8b00sm49213526d6.17.2025.03.19.12.46.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Mar 2025 12:46:11 -0700 (PDT) Date: Wed, 19 Mar 2025 15:46:10 -0400 From: Johannes Weiner To: Yosry Ahmed Cc: Greg Thelen , Tejun Heo , Michal =?iso-8859-1?Q?Koutn=FD?= , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Eric Dumazet Subject: Re: [PATCH] cgroup/rstat: avoid disabling irqs for O(num_cpu) Message-ID: <20250319194610.GF1876369@cmpxchg.org> References: <20250319071330.898763-1-gthelen@google.com> <20250319180643.GC1876369@cmpxchg.org> <20250319191638.GD1876369@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250319191638.GD1876369@cmpxchg.org> X-Stat-Signature: 5wxrq98kte8fjw7h19khudkgd766xodk X-Rspamd-Queue-Id: 4D036180014 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1742413573-782274 X-HE-Meta: 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 I2S5JgVK 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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 Wed, Mar 19, 2025 at 03:16:42PM -0400, Johannes Weiner wrote: > On Wed, Mar 19, 2025 at 06:35:02PM +0000, Yosry Ahmed wrote: > > On Wed, Mar 19, 2025 at 02:06:43PM -0400, Johannes Weiner wrote: > > > (btw, why do we not have any locking around the root stats in > > > cgroup_base_stat_cputime_show()? There isn't anything preventing a > > > reader from seeing all zeroes if another reader runs the memset() on > > > cgrp->bstat, is there? Or double times...) > > > > (I think root_cgroup_cputime() operates on a stack allocated bstat, not > > cgrp->bstat) > > That was the case until: > > commit b824766504e49f3fdcbb8c722e70996a78c3636e > Author: Chen Ridong > Date: Thu Jul 4 14:01:19 2024 +0000 Nevermind, Tejun pointed me to the follow-up fix he's got already queued up: https://web.git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git/commit/?id=c4af66a95aa3bc1d4f607ebd4eea524fb58946e3 That brings it all back on the stack.