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=-3.9 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 5BDCAC47423 for ; Fri, 2 Oct 2020 09:07:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E07520672 for ; Fri, 2 Oct 2020 09:07:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Is53JiSI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387597AbgJBJHp (ORCPT ); Fri, 2 Oct 2020 05:07:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725993AbgJBJHo (ORCPT ); Fri, 2 Oct 2020 05:07:44 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AFA7AC0613D0; Fri, 2 Oct 2020 02:07:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=aAAbxNegoG0OkRLdkHrUKEVk3WJTcefZ9uoKJBagbcQ=; b=Is53JiSI75kIUyBY7cS1XVXNGy vcnb11qkmV1+lP+B9NJDFbDoAl3sln8dwUFS4vI2bFzddaNCp+7oJznrW2qsPeEWo2f7xEu+duoSA 7LktTOOVSg9ArSRL5Aj+L1PRbQjvuN81GMaXBBG15XSpScFw4/+mDpgC27gvy8y3Nd7DDjaSuu7OT A233bwcpaDi8gvUmWWkUEUpzJHQtvpFVwW6y4Z6i2XtSp83s9vaub71axs27XMXQZ20y1j9UnFxNo DVTNYv+JMwxnHj5TlCin3oTlIFH/FruijUpiyTMhqKRpZgXpJom+fcIRROCA4NMEWtN17eBDXWg3M FKmdTrGA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kOH2K-0007M3-72; Fri, 02 Oct 2020 09:07:32 +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 343843011E6; Fri, 2 Oct 2020 11:07:29 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1E38020104626; Fri, 2 Oct 2020 11:07:29 +0200 (CEST) Date: Fri, 2 Oct 2020 11:07:29 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Michal Hocko , Uladzislau Rezki , Vlastimil Babka , LKML , RCU , linux-mm@kvack.org, Andrew Morton , "Paul E . McKenney" , Thomas Gleixner , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [RFC-PATCH 2/4] mm: Add __rcu_alloc_page_lockless() func. Message-ID: <20201002090729.GU2628@hirez.programming.kicks-ass.net> References: <20200918194817.48921-1-urezki@gmail.com> <20200918194817.48921-3-urezki@gmail.com> <38f42ca1-ffcd-04a6-bf11-618deffa897a@suse.cz> <20200929220742.GB8768@pc636> <795d6aea-1846-6e08-ac1b-dbff82dd7133@suse.cz> <20201001192626.GA29606@pc636> <20201002071123.GB20872@dhcp22.suse.cz> <20201002085014.GC3227@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201002085014.GC3227@techsingularity.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 02, 2020 at 09:50:14AM +0100, Mel Gorman wrote: > On Fri, Oct 02, 2020 at 09:11:23AM +0200, Michal Hocko wrote: > > > +#define ___GFP_NO_LOCKS 0x800000u > > > > Even if a new gfp flag gains a sufficient traction and support I am > > _strongly_ opposed against consuming another flag for that. Bit space is > > limited. > > That is definitely true. I'm not happy with the GFP flag at all, the > comment is at best a damage limiting move. It still would be better for > a memory pool to be reserved and sized for critical allocations. This is one of the reasons I did a separate allocation function. No GFP flag to leak into general usage. > > Besides that we certainly do not want to allow craziness like > > __GFP_NO_LOCK | __GFP_RECLAIM (and similar), do we? > > That would deserve to be taken to a dumpster and set on fire. The flag > combination could be checked in the allocator but the allocator path fast > paths are bad enough already. Isn't that what we have CONFIG_DEBUG_VM for?