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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 04A59C433DB for ; Fri, 5 Feb 2021 12:04:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A39D464E0A for ; Fri, 5 Feb 2021 12:04:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230034AbhBEMEi (ORCPT ); Fri, 5 Feb 2021 07:04:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231274AbhBEMBo (ORCPT ); Fri, 5 Feb 2021 07:01:44 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F3F4C06178C for ; Fri, 5 Feb 2021 04:01:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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; bh=N+gr+woLTLTNRWLX/vD2ETBGIX1Ifu4DYG7FuQNse1k=; b=hCxamAsHHyDAuVzWIFep9r9AiT gQ9TBgt87Ye3nGZDVRVVHs2yT2VHkhxvjJi++AfGfu+HdEAI/heLBOEozSGXvkzlK4eWGtB6pOTrj nT8va00Ofe+D7enlu2iUJZ3MF+ph5G5w+4R9zGwmR7EyvDleOsfu7mJHptff1MXheQugPPZcJ8nfy auWm0iyq7WPDQbD+8LcDUnlnHmjBJS7M+ZGqqdaJZh3W9LjXHvY7s/XMrloWpQX7h0873VzRqKc5N PiDz41u5tfGEWWNuQvpkwhRl3f3dz4aCyhtWo/zWBKi7NdjXfukya0piKU2iYCVp8BNVt8zmh7NI7 qd0au5MA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1l7zmY-0002BK-0t; Fri, 05 Feb 2021 12:00:14 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4C85C305C1C; Fri, 5 Feb 2021 13:00:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 31D1E236804AF; Fri, 5 Feb 2021 13:00:11 +0100 (CET) Date: Fri, 5 Feb 2021 13:00:11 +0100 From: Peter Zijlstra To: "Joel Fernandes (Google)" Cc: Nishanth Aravamudan , Julien Desfossez , Tim Chen , Vineeth Pillai , Aaron Lu , Aubrey Li , tglx@linutronix.de, linux-kernel@vger.kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , vineeth@bitbyteword.org, Chen Yu , Christian Brauner , Agata Gruza , Antonio Gomez Iglesias , graf@amazon.com, konrad.wilk@oracle.com, dfaggioli@suse.com, pjt@google.com, rostedt@goodmis.org, derkling@google.com, benbjiang@tencent.com, Alexandre Chartre , James.Bottomley@hansenpartnership.com, OWeisse@umich.edu, Dhaval Giani , Junaid Shahid , jsbarnes@google.com, chris.hyser@oracle.com, Ben Segall , Josh Don , Hao Luo , Tom Lendacky Subject: Re: [PATCH v10 2/5] sched: CGroup tagging interface for core scheduling Message-ID: References: <20210123011704.1901835-1-joel@joelfernandes.org> <20210123011704.1901835-3-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210123011704.1901835-3-joel@joelfernandes.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 22, 2021 at 08:17:01PM -0500, Joel Fernandes (Google) wrote: > +int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2) > +{ > + static DEFINE_MUTEX(sched_core_tasks_mutex); > + unsigned long cookie; > + int ret = -ENOMEM; > + > + mutex_lock(&sched_core_tasks_mutex); > + > + if (!t2) { > + if (t1->core_task_cookie) { > + sched_core_put_task_cookie(t1->core_task_cookie); > + sched_core_update_task_cookie(t1, 0); > + sched_core_put(); > + } So this seems to be the bit that implements _CLEAR. ISTR there were security implications / considerations here. When the machine is vulnerable to L1TF/MDS and the like, clearing the cookie would gain privilege and should thus be subject to some checks, but I can'd find anything. At the very least that deserves a comment I'm thinking.