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 79474C433E3 for ; Thu, 13 Aug 2020 17:22:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A9F620866 for ; Thu, 13 Aug 2020 17:22:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726529AbgHMRWk (ORCPT ); Thu, 13 Aug 2020 13:22:40 -0400 Received: from mx2.suse.de ([195.135.220.15]:35918 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726174AbgHMRWj (ORCPT ); Thu, 13 Aug 2020 13:22:39 -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 83168B676; Thu, 13 Aug 2020 17:23:00 +0000 (UTC) Date: Thu, 13 Aug 2020 19:22:37 +0200 From: Michal Hocko To: Thomas Gleixner Cc: Uladzislau Rezki , paulmck@kernel.org, LKML , RCU , linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Matthew Wilcox , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko , Peter Zijlstra Subject: Re: [RFC-PATCH 1/2] mm: Add __GFP_NO_LOCKS flag Message-ID: <20200813172237.GU9477@dhcp22.suse.cz> References: <20200811210931.GZ4295@paulmck-ThinkPad-P72> <874kp87mca.fsf@nanos.tec.linutronix.de> <20200813075027.GD9477@dhcp22.suse.cz> <20200813095840.GA25268@pc636> <874kp6llzb.fsf@nanos.tec.linutronix.de> <20200813133308.GK9477@dhcp22.suse.cz> <87sgcqty0e.fsf@nanos.tec.linutronix.de> <20200813145335.GN9477@dhcp22.suse.cz> <87lfiitquu.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87lfiitquu.fsf@nanos.tec.linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 13-08-20 19:09:29, Thomas Gleixner wrote: > Michal Hocko writes: > > On Thu 13-08-20 16:34:57, Thomas Gleixner wrote: [...] I will go though the rest of the email tomorrow. > >> Really, if your primary lockless caches are empty then any allocation > >> which comes from deep atomic context should simply always fail. Being > >> stuck in an interrupt handler or even deeper for 200+ microseconds > >> waiting for zone lock is just bonkers IMO. > > > > That would require changing NOWAIT/ATOMIC allocations semantic quite > > drastically for !RT kernels as well. I am not sure this is something we > > can do. Or maybe I am just missing your point. > > I really do not understand why you think that it affects everything. We are likely not on the same page here. Are you talking about the original proposal in this thread (aka a new flag) or a way to reuse existing gfp space (http://lkml.kernel.org/r/20200813075027.GD9477@dhcp22.suse.cz) with a modification that would both silence the lockdep and keep the existing NOWAIT semantic? Sorry bear with me but I am getting lost in this thread. -- Michal Hocko SUSE Labs