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=-4.0 required=3.0 tests=BAYES_00, 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 CD634C433E4 for ; Thu, 13 Aug 2020 19:13:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8B2C2078B for ; Thu, 13 Aug 2020 19:13:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726593AbgHMTNu (ORCPT ); Thu, 13 Aug 2020 15:13:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:40378 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726292AbgHMTNu (ORCPT ); Thu, 13 Aug 2020 15:13:50 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C4D2CAF2F; Thu, 13 Aug 2020 19:14:10 +0000 (UTC) Date: Thu, 13 Aug 2020 21:13:47 +0200 From: Michal Hocko To: peterz@infradead.org Cc: "Paul E. McKenney" , Thomas Gleixner , Uladzislau Rezki , LKML , RCU , linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Matthew Wilcox , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [RFC-PATCH 1/2] mm: Add __GFP_NO_LOCKS flag Message-ID: <20200813191347.GV9477@dhcp22.suse.cz> References: <874kp6llzb.fsf@nanos.tec.linutronix.de> <20200813133308.GK9477@dhcp22.suse.cz> <87sgcqty0e.fsf@nanos.tec.linutronix.de> <20200813145335.GN9477@dhcp22.suse.cz> <20200813154159.GR4295@paulmck-ThinkPad-P72> <20200813155412.GP9477@dhcp22.suse.cz> <20200813160442.GV4295@paulmck-ThinkPad-P72> <20200813161357.GQ9477@dhcp22.suse.cz> <20200813162904.GX4295@paulmck-ThinkPad-P72> <20200813183121.GY2674@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813183121.GY2674@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 13-08-20 20:31:21, Peter Zijlstra wrote: > On Thu, Aug 13, 2020 at 09:29:04AM -0700, Paul E. McKenney wrote: [...] > > 3. Reusing existing GFP_ flags/values/whatever to communicate > > the raw-context information that was to be communicated by > > the new GFP_ flag. > > > > 4. Making lockdep forgive acquiring spinlocks while holding > > raw spinlocks, but only in CONFIG_PREEMPT_NONE=y kernels. > > > > Am I missing anything? > > How would 4 solve anything? Nothing on its own but along with http://lkml.kernel.org/r/20200813075027.GD9477@dhcp22.suse.cz it would allow at least _some_ NOWAIT semantic for RT atomic contexts and prevent from lockdep false positives for !RT trees. -- Michal Hocko SUSE Labs