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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1FEFEC5B57D for ; Tue, 2 Jul 2019 07:01:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EDC5821721 for ; Tue, 2 Jul 2019 07:01:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727076AbfGBHBQ (ORCPT ); Tue, 2 Jul 2019 03:01:16 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:37585 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbfGBHBQ (ORCPT ); Tue, 2 Jul 2019 03:01:16 -0400 Received: by mail-wr1-f67.google.com with SMTP id v14so16405634wrr.4 for ; Tue, 02 Jul 2019 00:01:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=j8lK5kIXp0UqDp4JIzbWUup5nSgUhdrymM+k2oGTEDc=; b=fbRnBucU6ENh5ePnY/Xja6zenz23moszKZ4AW/14c1aYhjfkZuQ0311SX3Fmh1icC6 47kuyUOXNHziCYl3dn/FYQB09dmOYUCVhvgQCcUSmzglddyAF/v/GUX+i2tBUslQvIR3 JqEeN2i5PAFKq1WoeHQ9L6B//vbrdrXK7f1OzuC0W0M9FCLdUYXW7g78Vpf0sDpESOOq V5KMBiSO7fsbMTXcxB3rHpHMDIouDfNuZXzqdxo0X3/01zhX3XPtPsYvAx0WeuLDe5QB N29jkrMrlWwvFyP3pJb5u0VaDdAX/yr4IXUcisQTb0KWoc32Kr603pxW6EqQ54JGHGq2 PQFA== X-Gm-Message-State: APjAAAUWr7HGDsbYX92tyzB+Z/mmgiA2tvUUf0+w7Nn0CDdhKYhpI78U Cn21C5C804FmWlycAg82KfsbtA== X-Google-Smtp-Source: APXvYqxOHUPpYjdAAg6clNrlcbEiwLlc67t9bfS8ALzT5Vbf5YgNxPVDD80/N0s1sHlnf0pD9kkMvQ== X-Received: by 2002:adf:dd8c:: with SMTP id x12mr22298053wrl.212.1562050874833; Tue, 02 Jul 2019 00:01:14 -0700 (PDT) Received: from localhost.localdomain ([151.15.224.253]) by smtp.gmail.com with ESMTPSA id r16sm24718434wrr.42.2019.07.02.00.01.13 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 02 Jul 2019 00:01:13 -0700 (PDT) Date: Tue, 2 Jul 2019 09:01:12 +0200 From: Juri Lelli To: Peter Zijlstra Cc: mingo@redhat.com, rostedt@goodmis.org, tj@kernel.org, linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it, claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it, bristot@redhat.com, mathieu.poirier@linaro.org, lizefan@huawei.com, cgroups@vger.kernel.org Subject: Re: [PATCH v8 7/8] sched/core: Prevent race condition between cpuset and __sched_setscheduler() Message-ID: <20190702070111.GF26005@localhost.localdomain> References: <20190628080618.522-1-juri.lelli@redhat.com> <20190628080618.522-8-juri.lelli@redhat.com> <20190701191141.GD3402@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190701191141.GD3402@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/07/19 21:11, Peter Zijlstra wrote: > On Fri, Jun 28, 2019 at 10:06:17AM +0200, Juri Lelli wrote: > > No synchronisation mechanism exists between the cpuset subsystem and > > calls to function __sched_setscheduler(). As such, it is possible that > > new root domains are created on the cpuset side while a deadline > > acceptance test is carried out in __sched_setscheduler(), leading to a > > potential oversell of CPU bandwidth. > > > > Grab cpuset_rwsem read lock from core scheduler, so to prevent > > situations such as the one described above from happening. > > > > ISTR there being a funny vs normalize_rt_tasks(); maybe mention that? Yep. I'll add a comment about it.