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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F2FD1C0015E for ; Thu, 13 Jul 2023 04:51:54 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4R1hzF2xc6z3c2J for ; Thu, 13 Jul 2023 14:51:53 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.alibaba.com (client-ip=115.124.30.130; helo=out30-130.freemail.mail.aliyun.com; envelope-from=hsiangkao@linux.alibaba.com; receiver=lists.ozlabs.org) Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4R1hz70mrPz3bjK for ; Thu, 13 Jul 2023 14:51:45 +1000 (AEST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=hsiangkao@linux.alibaba.com;NM=1;PH=DS;RN=21;SR=0;TI=SMTPD_---0VnFjj4L_1689223895; Received: from 30.97.48.217(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0VnFjj4L_1689223895) by smtp.aliyun-inc.com; Thu, 13 Jul 2023 12:51:36 +0800 Message-ID: Date: Thu, 13 Jul 2023 12:51:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v1] rcu: Fix and improve RCU read lock checks when !CONFIG_DEBUG_LOCK_ALLOC To: paulmck@kernel.org References: <20230711233816.2187577-1-dhavale@google.com> <20230713003201.GA469376@google.com> <161f1615-3d85-cf47-d2d5-695adf1ca7d4@linux.alibaba.com> <0d9e7b4d-6477-47a6-b3d2-2c9d9b64903d@paulmck-laptop> From: Gao Xiang In-Reply-To: <0d9e7b4d-6477-47a6-b3d2-2c9d9b64903d@paulmck-laptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-team@android.com, Will Shiu , linux-erofs@lists.ozlabs.org, Frederic Weisbecker , Lai Jiangshan , Josh Triplett , Steven Rostedt , linux-kernel@vger.kernel.org, rcu@vger.kernel.org, Matthias Brugger , Mathieu Desnoyers , Joel Fernandes , linux-mediatek@lists.infradead.org, Zqiang , Neeraj Upadhyay , Boqun Feng , linux-arm-kernel@lists.infradead.org, AngeloGioacchino Del Regno Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" On 2023/7/13 12:27, Paul E. McKenney wrote: > On Thu, Jul 13, 2023 at 10:02:17AM +0800, Gao Xiang wrote: >> >> ... sorry forget some. > > One additional question... What is your plan for kernels built with > CONFIG_PREEMPT_COUNT=n? After all, in such kernels, there is no way > that I know of for code to determine whether it is in an RCU read-side > critical section, holding a spinlock, or running with preemption disabled. I'm not sure if Android (or all targetted) users use or care about this configuration (CONFIG_PREEMPT_COUNT=n), personally I think for such configuration we could just fall back to the workqueue approach all the time. Anyway, such optimization really comes from real workloads / experience, users don't live well without such mitigation. Thanks, Gao Xiang > > Thanx, Paul