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 D2D57C47089 for ; Thu, 27 May 2021 14:55:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B709E61284 for ; Thu, 27 May 2021 14:55:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236691AbhE0O5V (ORCPT ); Thu, 27 May 2021 10:57:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229793AbhE0O5S (ORCPT ); Thu, 27 May 2021 10:57:18 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58404C061574; Thu, 27 May 2021 07:55:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=h+ribFfVIk329pe0p3tIyYOdBOtZCkKF+HnqMs1ehyM=; b=WYGVpiEixpBSdl2wAok68xEwTI M8GhhPdN5o6HfOKT4cuaGbQBJh/k/AI8irIdK9XmR9tZ1WvddhlNhvAbyMxem4onjg9pO8T2PiCeI 4D+Q7afmXuDAp1GQv5327Z5uWK7XlwLuRcKKjog0Ft0QulMDaMiqRRGY1APG9H1VuaHUv+0Rs8bZQ 8TcblaHKv6zYdu78gOTaqFdQ9chtD1O2c6lLhPQvUVA+XFJCbFrMMC8UhCFZgeScnoiosnkunvHSq tQPWlLWAb/VJy+fq6tEmuGuxYxIx7KOyPYqj/wEdjIO8BC98Tsgq+2fFysrvSsGl45saCF3MSS4jq 6OewL+bw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1lmHPz-00123b-6c; Thu, 27 May 2021 14:55:34 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 2CDBC300221; Thu, 27 May 2021 16:55:33 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 127C12011BE77; Thu, 27 May 2021 16:55:33 +0200 (CEST) Date: Thu, 27 May 2021 16:55:32 +0200 From: Peter Zijlstra To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , Dietmar Eggemann , Daniel Bristot de Oliveira , kernel-team@android.com Subject: Re: [PATCH v7 16/22] sched: Defer wakeup in ttwu() for unschedulable frozen tasks Message-ID: References: <20210525151432.16875-1-will@kernel.org> <20210525151432.16875-17-will@kernel.org> <20210527144412.GB23086@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210527144412.GB23086@willie-the-truck> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 27, 2021 at 03:44:12PM +0100, Will Deacon wrote: > I'm not seeing how this handles tasks which weren't put in the freezer > because they have PF_FREEZER_SKIP set. For these tasks, we need to make > sure that they don't become runnable before we have onlined a core which > is capable of running them, and this could occur because of any old > wakeup (i.e. whatever it was that they blocked on). I was under the impression that userspace tasks could not have PF_FREEZER_SKIP set.. let me look harder.