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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADA00C61D97 for ; Mon, 30 Jan 2023 18:01:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237393AbjA3SBg (ORCPT ); Mon, 30 Jan 2023 13:01:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237463AbjA3SBa (ORCPT ); Mon, 30 Jan 2023 13:01:30 -0500 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE75C3E616; Mon, 30 Jan 2023 10:01:27 -0800 (PST) Received: by mail-pj1-x1033.google.com with SMTP id e8-20020a17090a9a8800b0022c387f0f93so11271223pjp.3; Mon, 30 Jan 2023 10:01:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=I4D1Ztp5PXdnjePzURg65Mwo279xYxNPa3f1/sKE5u4=; b=P28ybXbqk2lUQqqrphJjk3zFN2/7Ucbw6CuzRIwJahxQ7K4MRZhALIYagoVDPYFWjO 2Q51er32H9qfSTZNepRmTyVQVLX0Rm+jkg7cfMgfc0qSjN4hapg6vklx6rESi+CO2fXb 0BbWtRy04i1kxXbSo2XE+PuSBJ61G5jC1vtiOfX8sFv/VUOtNnOr3pu9UiLNAL1Ee+k5 purXcAwlBZ7hzw7sq/D5XmM3rA2DXDf+PVaGnP98DKpIv81uKcSpQLxmHPSw9rPWdtm/ 7cGZkdwSqjpQKym7TFguaUgvz5qaW/UdQ8e8z0OatL+23U6Hi50W1eG4ngJa84Iryd0k /o/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=I4D1Ztp5PXdnjePzURg65Mwo279xYxNPa3f1/sKE5u4=; b=wYQ1HkBLvxeD9QiSDGjc4XAjDGjLWMnXR3Rbp9tRGTgq6/b+GZJOPvSioq1XAqzqpn klZ0n95Lg20MG+Fh2Jpszy1GZiUa9Iwi4/E1FifN2dbin7icmSMj35tVlIZYMYsqmnhp Yo5DIYSx3VJtZdm8+jRu5FM4PMd0GG+LtUtf1nKoY650ymPXtROxdyxW37e1wLa5YcuO QnFUzNI80ezLMEX6h2UNg1SY8Rx5fTy5eaDV80YuIIlRYHEn6mERgdSQmx5MWkl0+7Uo Mto88tEk1G1tY+fhfLJmXN5Yh/tRUhmaqiKRULl9Dfsbhwd0hDbz19ttC/dr/z865tR1 ZhoQ== X-Gm-Message-State: AO0yUKXJamN66mLBxspFXcp4HkzR6h2OZy7bfUWD76akAX3iV8p6G14L BqPVArF0xsdIYPHOBCa3SiE= X-Google-Smtp-Source: AK7set9Vi/N1eTHHTsLb46fowrg6kZs54hy5jnjNYC/R7hR10XQucmJtGgVjqA8aR7sEEtyjOUQgaA== X-Received: by 2002:a17:903:2093:b0:192:ef8e:4258 with SMTP id d19-20020a170903209300b00192ef8e4258mr6351497plc.14.1675101686559; Mon, 30 Jan 2023 10:01:26 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id ix1-20020a170902f80100b001960e9dd05esm8111845plb.112.2023.01.30.10.01.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Jan 2023 10:01:26 -0800 (PST) Sender: Tejun Heo Date: Mon, 30 Jan 2023 08:01:24 -1000 From: Tejun Heo To: Ming Lei Cc: Christoph Hellwig , Jens Axboe , Josef Bacik , linux-block@vger.kernel.org, cgroups@vger.kernel.org, Andreas Herrmann Subject: Re: [PATCH 01/15] blk-cgroup: don't defer blkg_free to a workqueue Message-ID: References: <20230124065716.152286-1-hch@lst.de> <20230124065716.152286-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sat, Jan 28, 2023 at 11:12:13PM +0800, Ming Lei wrote: > On Tue, Jan 24, 2023 at 07:57:01AM +0100, Christoph Hellwig wrote: > > Now that blk_put_queue can be called from process context, there is no > > s/process/atomic? > > > need for the asynchronous execution. > > > > This effectively reverts commit d578c770c85233af592e54537f93f3831bde7e9a. > > blkg_free() can be called with ->queue_lock, and: > > - del_timer_sync(&tg->service_queue.pending_timer) is called from throtl_pd_free(). > > - queue_lock is required by throtl_pending_timer_fn > > So there is deadlock risk if the above commit is reverted. Ah, good catch. Looks like we'd have to leave this async. Thanks. -- tejun