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 96B32C2D0E5 for ; Wed, 25 Mar 2020 19:19:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CBCE206F6 for ; Wed, 25 Mar 2020 19:19:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585163968; bh=jfHM2jx4sKCtd/J/qfxgIFN0o1REbZioijNAl4LQAc8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ZXIow7Fw4H/mVNyoyLHWtDQa3Ty34YCnXv5sdpvSPCc4y3kvbn6UNuJItMtHbVH1F Tj1aouCqoymsFJWw0cSBUkN8OTJSzhgD3QdMf1lXVh86ArGbJl8nl2fgTwmkD9TjGv IE5I/368ZsVh62/MFg0esdGqRif6/eDZBW5YpvnE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727665AbgCYTT1 (ORCPT ); Wed, 25 Mar 2020 15:19:27 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:42031 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727174AbgCYTT0 (ORCPT ); Wed, 25 Mar 2020 15:19:26 -0400 Received: by mail-qt1-f193.google.com with SMTP id t9so3204697qto.9; Wed, 25 Mar 2020 12:19:26 -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=rOPBVRyRj22r/QAr9s4b9CBOGy0xlM6KuJUxnB7ao+I=; b=WshBHS0wCQtRNGoEZsyzPMrxTJcVcepRsbvcpB1+hCJTpUBqa7ilY0cDflaaTzY0D+ uuPEzzE2uM7eb/nZ0dwz2vQpq8xuKrREIdIVHuh1pixYEMyM+0/VFQqEKjYCQLmcvCoT VLXYgbgKtuUxFrVXKmAZsa4SQLponxT8Kush70OqvoWnIB4OCkzALZv/8lKYOXhKkdKb qlWfDaAFjW7GhpB/atmTETI+rYYxr1gufl0fZvq4474QfO6PTT7jCII1aDcQyQg/CUxX uA9anhzPVs0Zu7KLoWDg++XyTOIXQYVrFRiPJ7IG1SJtvv9/0XoeIZPm1i1TNET1liF3 xCdQ== 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=rOPBVRyRj22r/QAr9s4b9CBOGy0xlM6KuJUxnB7ao+I=; b=qceDLoijw2YfXoPGdcNtywgIYGW5wMmViS6uY3+HakU/neTwZQmK4OpYIhDJWyN3g8 PaHuJUAMjWIRN88/fqwoigQkKt3lQ0a5GRnNxBExfdVB6jE+V+Hnm2WLeSIkq2NkcH4i xqPGrISTZccXrJv/7YmphxTz90qJXGtDu+udIFJvGBlpEVX8tta6dC1RX5Zzz6SytjJC B422S/wtE0K+M/Dlc8fgeKGK49BTEx1p1GSykKUJFfkWyTUftv2kcQwCTeWxj0+40KnN Y5AqZT1ujOabaoNum2CXrchK7NfkD+sezUX2G5xLtP+tTzLjEyRnCEHc8x4sfzLTUob5 HTdQ== X-Gm-Message-State: ANhLgQ2xIZ2mc/CHTjwudLUkHHazv7UhXj31VLQR7o5AVLWYZCbvY1yJ INIcrdNvsYKzmCKUu6EHZQc= X-Google-Smtp-Source: ADFU+vuaylKzh2WDvL6nXEaYyf0iBNZxB/JqfhMsuKd4DsgrMsWOHRt03W96QML3WCec3KuEmA0vBw== X-Received: by 2002:aed:200f:: with SMTP id 15mr4567779qta.152.1585163965488; Wed, 25 Mar 2020 12:19:25 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::d8d4]) by smtp.gmail.com with ESMTPSA id z18sm18199199qtz.77.2020.03.25.12.19.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 12:19:24 -0700 (PDT) Date: Wed, 25 Mar 2020 15:19:22 -0400 From: Tejun Heo To: Qian Cai Cc: Prateek Sood , Li Zefan , cgroups@vger.kernel.org, LKML , Peter Zijlstra Subject: Re: Deadlock due to "cpuset: Make cpuset hotplug synchronous" Message-ID: <20200325191922.GM162390@mtj.duckdns.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks. -- tejun