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 X-Spam-Level: X-Spam-Status: No, score=-1.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D318C2BB54 for ; Tue, 7 Apr 2020 13:35:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E2E0206F7 for ; Tue, 7 Apr 2020 13:35:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586266525; bh=t4bv0J28enUiM60tnCiClhpvroA/fwreaN1V/SU8S6U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=LUG/dLVlaNzp69qkO9lq27K5isGw0wxCbehi+iHvPtPxtnHEihq/LXTaHk3jUW7ML XzzeyQw6SsHMJ6aVtyhL1bC/pO83DyHBu6uoSFh4IpecGCT2LvqJgqeuohUJmDcWHD 3azUwT3T/eb4OLNExvkVgQAUA8ow4D4ZQO0BLQSw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728914AbgDGNfY (ORCPT ); Tue, 7 Apr 2020 09:35:24 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:39580 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728482AbgDGNfY (ORCPT ); Tue, 7 Apr 2020 09:35:24 -0400 Received: by mail-qk1-f195.google.com with SMTP id b62so1587474qkf.6; Tue, 07 Apr 2020 06:35:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=odzEhtuT1mkH5cv+06XvJ0mo1X9dWs4O45m8red/YFE=; b=lLPy54IqRiVI+gbF9bXttpMrnAgkCN0tMMlu1yiVIlS2/nkavZOJukt5viyskCkZCp /a3SWshrpdGsMCXv86eLzNPxbhRKSq1M1Ot/P5T8kc+zlZg61ebkbREN6INJiTb9T/nd bnWH7iDmLuseRsFocSas0ZOCT1ZaGSfA8inB2kUB37Q0d++qtW3YXbb6oyUtpgmgRj4B Ag0sQG+/+CRN2rKLdq+v2y00f8KGMwhdteP1POMgqhxUMBoefVpWT42aNaOUUb/cTIFw gWOHqN/gsvLlUHfCdmtSVn+SNDRwcyPuDSBY5pHYyLlkWMElV+QQ+GpDCw1CYnZ1hXk4 gGXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=odzEhtuT1mkH5cv+06XvJ0mo1X9dWs4O45m8red/YFE=; b=jepqtQPF9DWDGySZZdgJM9Gavkslj+uAIWAq2pC41CjWoQhMNaDlarPPZ6k5hpHNM9 nTKKkZiyUyCb5gw/g0CYw4xxUYLVbFNbMGMZvMFGW/0URbRFuM2Nc2oJoVk4O+6TxJAN OANLdArJgH6/FYAk5aa7CBrE7VMvKbsqejH/BDoGiTPS75bhV5PK+7LI3cxcFtznirQU f72A2HZyBM5yIGkRTrkaEIj6OW63ZaoYgX+TI6e6yGmPPdd0x+9XkDJxWjgOSUbmhe3b pmi9BAv8LxQcZjTUIQSOKiWVw0Sno8pfYqbbSSs/08qiZZ0KNdaa9ciRiMyLm4cnLkj3 ZnQA== X-Gm-Message-State: AGi0PuZtfMJVetA2jXrpHyt+CsyXLaxDQ/fBmzsCRVZef3WXF8bpgjRp nOLL2hEHibl8miZdfdptxBI= X-Google-Smtp-Source: APiQypLEqD0fQclX3tUCPeigphzqR8Cy8D/rzw25UKOBzyLv8uRQqnVSNxgvxJozLd7DoX9+FIVO+A== X-Received: by 2002:a37:670a:: with SMTP id b10mr2205766qkc.342.1586266522385; Tue, 07 Apr 2020 06:35:22 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::ceda]) by smtp.gmail.com with ESMTPSA id a19sm16799360qtp.5.2020.04.07.06.35.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2020 06:35:21 -0700 (PDT) Date: Tue, 7 Apr 2020 09:35:20 -0400 From: Tejun Heo To: Qais Yousef Cc: Qian Cai , Prateek Sood , Li Zefan , cgroups@vger.kernel.org, LKML , Peter Zijlstra Subject: Re: Deadlock due to "cpuset: Make cpuset hotplug synchronous" Message-ID: <20200407133520.GI162390@mtj.duckdns.org> References: <20200325191922.GM162390@mtj.duckdns.org> <20200326101529.xh763j5frq2r7mqv@e107158-lin> <20200403145523.GC162390@mtj.duckdns.org> <20200406105522.c66p4vzzzylety5d@e107158-lin.cambridge.arm.com> <20200406143405.GH162390@mtj.duckdns.org> <20200407130725.jhtth3bneo33zex6@e107158-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200407130725.jhtth3bneo33zex6@e107158-lin.cambridge.arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 07, 2020 at 02:07:26PM +0100, Qais Yousef wrote: > On 04/06/20 10:34, Tejun Heo wrote: > > On Mon, Apr 06, 2020 at 11:55:23AM +0100, Qais Yousef wrote: > > > What would be the right approach to get a fix in then? We have been skipping > > > this test for a while and we'd like to enable it but this failure is a > > > blocking issue. > > > > Update the test so that it accounts for the async nature of the operation? > > With a sleep() between the hp ops and the read? Isn't this a nasty hack? Some operations are just async. Why is that inherently wrong? > I was just trying to find out what can be done for 5.7. But based on your > response this is sadly a dead end. For no reason I can comprehend. Because it's creating real issues while trying to address a non-real problem. It's dumb. Fix the non-real part. Thanks. -- tejun