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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 952D5C0650E for ; Mon, 1 Jul 2019 19:12:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7368B2146F for ; Mon, 1 Jul 2019 19:12:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="eU/iOVhJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726859AbfGATMR (ORCPT ); Mon, 1 Jul 2019 15:12:17 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:58960 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726563AbfGATMR (ORCPT ); Mon, 1 Jul 2019 15:12:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0htxnIK1Wduic/JIKCNlUJk+0wwHKgV99WAuI//uAS4=; b=eU/iOVhJKXcr8fi85AGcX1pY0 NK0W9Vf632ZZzWS3+uVfZHCOuWraFnZqUiMSLdsB+yZP3coujr95WDGbyehXOn12VDCiSHkS9BT98 vL1LUFqKKaDBsBzcCoKCxgDz23AlcvkBWW8UIamqfDzzlsC8F8UjCal71OW9/wfrm2rPTSgUD9Fgn k5SOfS2/YiWiRAfzJjljIEmKgPqu9DK7PQmLuq6vj+ZJMEzE0w/CjD/2Zs2Xc6/kcXuBlB3xUriWL 2CwXWDAAhf7TMX49hYAjonRDY0Lu2jV4cUErlgH6Qu8HFEmHeiRqqNyRMBf4E5Ag+cRwzeD2P+NMa +2vYCgmGg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hi1iJ-0001Vs-61; Mon, 01 Jul 2019 19:11:43 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6E40E2013A20D; Mon, 1 Jul 2019 21:11:41 +0200 (CEST) Date: Mon, 1 Jul 2019 21:11:41 +0200 From: Peter Zijlstra To: Juri Lelli 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: <20190701191141.GD3402@hirez.programming.kicks-ass.net> References: <20190628080618.522-1-juri.lelli@redhat.com> <20190628080618.522-8-juri.lelli@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190628080618.522-8-juri.lelli@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?