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=-1.1 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 BF5D4C43331 for ; Fri, 3 Apr 2020 14:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85CAF20CC7 for ; Fri, 3 Apr 2020 14:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585925730; bh=X9QK3DxM8PocBDuHpjw1TreDlIixWPpzHdlQR28SBnc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=b7/BrnCIbWFCpwDj6yLuPOGcwDD+wUfzrQjHa4BwK7AaVlACZHtaXA2xJZun3YW2y Lp352/2MHMbHS0rz+Cbm/0/Zi4q4TqEwa1yh8Lv0UTP+THbkloV4wyqGmsW/qcNtsq x34AVDPu3v1EaWIHyoqcNF3eAxfOcrULZXr8K7Lo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404100AbgDCOz3 (ORCPT ); Fri, 3 Apr 2020 10:55:29 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:34654 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404079AbgDCOz1 (ORCPT ); Fri, 3 Apr 2020 10:55:27 -0400 Received: by mail-qt1-f195.google.com with SMTP id 14so6387839qtp.1; Fri, 03 Apr 2020 07:55:26 -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:content-transfer-encoding:in-reply-to; bh=WueqobVTQhcuC12qhXxBjSlUXTsOjQxipqHLExYdXc0=; b=r1b480yVF4TVvjrmu9e9b50NuC47Vk3m0YSl40WOSeQXq8lJeps/ADO+KJNjeKJzJj aGGZJZfUuaq3cRlitmPYQ2IQv77nhZDHwTOFW4atm0XMsImQWiDGLolaa9PagsIpXjgb EM2oNoZdvmXAhaoNA0X7jbbK3rIy8dL8zcXGxbVDVblZmNjnIRyoagBiqvD5Wg0DfMft Je19HLCWupm6dDLYgsaD2ZSvaSjPdO2mdFOlfM68Q7pRDcuIodjlvnxsEyHv1ozQY4VN td2ZZZmZjc3IOVeCUgGknW+DVuUoBKjpERAgu440DgNTZua5AIfvoANdbzhN23UAUpXq kuTQ== 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 :content-transfer-encoding:in-reply-to; bh=WueqobVTQhcuC12qhXxBjSlUXTsOjQxipqHLExYdXc0=; b=WTC2VyVjGW6Bdvq3uq0HhQ47SRmgpyi/1gnYae1brmpJjJu6sZl3g3I3hb/F2E5ZeC etMDHQIH2F1+wobgxul9kwd0jbDqCPvnDBAzMacKgmF3r+7kVXvG5zLMCgiBO4GIW/8j sTqQlbS7tRSTQ4Cx1h1oA6Y/eChuL3fbSXwVii1dDTtfsr5I4r1dFBz9xAvABbJYHZBE yYnAWHHDd8n8kGvnnY3+/cIO7EYo9hChd2BsaElLClCQpwIhuDu4V1hvU9Fk4FdweaKo Syg/MxHOr4qelEze3qy5F9/z58rn5oG2ZomyOeJo8n/yQljBWhax6K9bmDkiUWuO2p5O fDVA== X-Gm-Message-State: AGi0PuZkh6d23U1jHy707FK6BcAfWXvHZjZUk75s4QeK+Db1wDVQzqi6 M9mbOTUB4nsrgd8qWaBd19A= X-Google-Smtp-Source: APiQypIWYRFn9PmjXGuhOXLCtTNa/5UW/zyNPX9KmNkdo6y3Q3MtaY+o4pitao0ov7CK3dInjarMMg== X-Received: by 2002:ac8:2f15:: with SMTP id j21mr8898994qta.55.1585925726184; Fri, 03 Apr 2020 07:55:26 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::842b]) by smtp.gmail.com with ESMTPSA id f188sm3895379qkd.101.2020.04.03.07.55.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2020 07:55:25 -0700 (PDT) Date: Fri, 3 Apr 2020 10:55:23 -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: <20200403145523.GC162390@mtj.duckdns.org> References: <20200325191922.GM162390@mtj.duckdns.org> <20200326101529.xh763j5frq2r7mqv@e107158-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200326101529.xh763j5frq2r7mqv@e107158-lin> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 26, 2020 at 10:15:32AM +0000, Qais Yousef wrote: > On 03/25/20 15:19, Tejun Heo wrote: > > On Wed, Mar 25, 2020 at 03:16:56PM -0400, Qian Cai wrote: > > > The linux-next commit a49e4629b5ed (“cpuset: Make cpuset hotplug synchronous”) > > > introduced real deadlocks with CPU hotplug as showed in the lockdep splat, since it is > > > now making a relation from cpu_hotplug_lock —> cgroup_mutex. > > > > Prateek, can you please take a look? Given that the merge window is just around > > the corner, we might have to revert and retry later if it can't be resolved > > quickly. > > I've ran cpuset_hotplug and cpuhotplug LTP tests using next-20200325 but > couldn't reproduce it. > > Hopefully that can be fixed, but if you had to revert it, do you mind picking > this instead to fix the LTP issue I encountered before? > > https://lore.kernel.org/lkml/20200211141554.24181-1-qais.yousef@arm.com/ So, I'd rather not, for now anyway. It isn't a real problem and I don't wanna add a wait vector there. Thanks. -- tejun