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=-5.3 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,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 7CAEEC47423 for ; Fri, 2 Oct 2020 07:11:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3951F206A2 for ; Fri, 2 Oct 2020 07:11:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="SqC3XLQc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726251AbgJBHL0 (ORCPT ); Fri, 2 Oct 2020 03:11:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:51870 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725948AbgJBHLZ (ORCPT ); Fri, 2 Oct 2020 03:11:25 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601622684; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=CIUDRMv6oCpat1m7gSDcNYYd2XmvpMkcwYlQlsCJ1pI=; b=SqC3XLQcMGZ9Sb9YZP0PRZTA34Gr2lF5MTEwILmKEZDIxkZQV8o3nNG6/OxH0z6kptk4wf w5jE2PNxvkB5nnVNvyRYsvDFRIVWTgZw/+3VPuBLeyd0znhxKLWFpXaWZGCRuY+AD7FDu+ mi88kOYCZ+LaVtK3zIR0tAuzyhgb0h4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 15038B317; Fri, 2 Oct 2020 07:11:24 +0000 (UTC) Date: Fri, 2 Oct 2020 09:11:23 +0200 From: Michal Hocko To: Uladzislau Rezki Cc: Vlastimil Babka , LKML , RCU , linux-mm@kvack.org, Andrew Morton , "Paul E . McKenney" , Peter Zijlstra , Thomas Gleixner , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko , Mel Gorman Subject: Re: [RFC-PATCH 2/4] mm: Add __rcu_alloc_page_lockless() func. Message-ID: <20201002071123.GB20872@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201001192626.GA29606@pc636> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 01-10-20 21:26:26, Uladzislau Rezki wrote: > > > > No, I meant going back to idea of new gfp flag, but adjust the implementation in > > the allocator (different from what you posted in previous version) so that it > > only looks at the flag after it tries to allocate from pcplist and finds out > > it's empty. So, no inventing of new page allocator entry points or checks such > > as the one you wrote above, but adding the new gfp flag in a way that it doesn't > > affect existing fast paths. > > > OK. Now i see. Please have a look below at the patch, so we fully understand > each other. If that is something that is close to your view or not: > > > t a/include/linux/gfp.h b/include/linux/gfp.h > index c603237e006c..7e613560a502 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -39,8 +39,9 @@ struct vm_area_struct; > #define ___GFP_HARDWALL 0x100000u > #define ___GFP_THISNODE 0x200000u > #define ___GFP_ACCOUNT 0x400000u > +#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. Besides that we certainly do not want to allow craziness like __GFP_NO_LOCK | __GFP_RECLAIM (and similar), do we? -- Michal Hocko SUSE Labs