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=-2.1 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 6B602C5DF60 for ; Fri, 8 Nov 2019 12:35:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C347222C6 for ; Fri, 8 Nov 2019 12:35:35 +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="s2ArXGVR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726742AbfKHMfd (ORCPT ); Fri, 8 Nov 2019 07:35:33 -0500 Received: from merlin.infradead.org ([205.233.59.134]:44176 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726039AbfKHMfd (ORCPT ); Fri, 8 Nov 2019 07:35:33 -0500 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: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=pMB7X5BsIcOFIG+976bGTn7Eu98OO5fDsIlf/eZjATk=; b=s2ArXGVRfAz8qyP2d9rrYCKFl 4FhL/rN2mujzn/jTzTSJVD3rQUIVIWw72IrU1jiP+Mzx6oak+xZ0gIxReG+Y9N9Hmj/KiBduu/p3/ GnkZumGk3JsxUhgCuSivGiP23b5oc1yz6TEuIeDsE7wx6J8IFi+s64Ea0iD4S5EGzw3q3eKUhqjrr 01MsrFExjaMHosxeXFuMXSoqfL8DLu+egF+ZoGS7rqq1QvGYqrsLlqM/jgbI+G5VO+mHq/tO/d7Mn bm7YLu5gzj4wj4ZfImntFy8xSCejVF3vP38wLG0J4owxYxpl4/TP1BD7O8vSmkV7UTRlJ3Zuug2pZ a/Hdh6EFw==; 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 1iT3Tw-0002u7-Um; Fri, 08 Nov 2019 12:35:17 +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 378FF303F45; Fri, 8 Nov 2019 13:34:10 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 25E1D28722B70; Fri, 8 Nov 2019 13:35:15 +0100 (CET) Date: Fri, 8 Nov 2019 13:35:15 +0100 From: Peter Zijlstra To: Quentin Perret Cc: Kirill Tkhai , linux-kernel@vger.kernel.org, aaron.lwe@gmail.com, valentin.schneider@arm.com, mingo@kernel.org, pauld@redhat.com, jdesfossez@digitalocean.com, naravamudan@digitalocean.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, juri.lelli@redhat.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, kernel-team@android.com, john.stultz@linaro.org Subject: Re: NULL pointer dereference in pick_next_task_fair Message-ID: <20191108123515.GL4131@hirez.programming.kicks-ass.net> References: <20191106165437.GX4114@hirez.programming.kicks-ass.net> <20191106172737.GM5671@hirez.programming.kicks-ass.net> <831c2cd4-40a4-31b2-c0aa-b5f579e770d6@virtuozzo.com> <20191107132628.GZ4114@hirez.programming.kicks-ass.net> <20191107153848.GA31774@google.com> <20191107184356.GF4114@hirez.programming.kicks-ass.net> <20191107192907.GA30258@worktop.programming.kicks-ass.net> <20191108110212.GA204618@google.com> <20191108120034.GK4131@hirez.programming.kicks-ass.net> <20191108121526.GB83597@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191108121526.GB83597@google.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, Nov 08, 2019 at 12:15:26PM +0000, Quentin Perret wrote: > Right, with a single loop you'll have to re-iterate the classes from > the start in case of RETRY_TASK, but you're re-iterating all the classes > too with this patch. You're doing a little less work in the second loop > though, so maybe it's worth it. The thing with the restart is that it'll make your head explode when we go do core-scheduling. > And I was the one worried about > refactoring the code too much close to the release, so maybe that's for > another time ;) It is either this patch or reverting a bunch of patches :/