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=-5.2 required=3.0 tests=BAYES_00, 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 05169C4363D for ; Fri, 2 Oct 2020 08:50:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 81D6F206DC for ; Fri, 2 Oct 2020 08:50:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81D6F206DC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D5D336B005D; Fri, 2 Oct 2020 04:50:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D0DD46B0062; Fri, 2 Oct 2020 04:50:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BFD62900002; Fri, 2 Oct 2020 04:50:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0060.hostedemail.com [216.40.44.60]) by kanga.kvack.org (Postfix) with ESMTP id 940276B005D for ; Fri, 2 Oct 2020 04:50:20 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id AE135181AE867 for ; Fri, 2 Oct 2020 08:50:18 +0000 (UTC) X-FDA: 77326363716.22.bike06_120fafe271a2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 8890818038E60 for ; Fri, 2 Oct 2020 08:50:18 +0000 (UTC) X-HE-Tag: bike06_120fafe271a2 X-Filterd-Recvd-Size: 3854 Received: from outbound-smtp29.blacknight.com (outbound-smtp29.blacknight.com [81.17.249.32]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Fri, 2 Oct 2020 08:50:17 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp29.blacknight.com (Postfix) with ESMTPS id 37977BEBA8 for ; Fri, 2 Oct 2020 09:50:16 +0100 (IST) Received: (qmail 20546 invoked from network); 2 Oct 2020 08:50:15 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 2 Oct 2020 08:50:15 -0000 Date: Fri, 2 Oct 2020 09:50:14 +0100 From: Mel Gorman To: Michal Hocko Cc: Uladzislau Rezki , 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 Subject: Re: [RFC-PATCH 2/4] mm: Add __rcu_alloc_page_lockless() func. Message-ID: <20201002085014.GC3227@techsingularity.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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20201002071123.GB20872@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Oct 02, 2020 at 09:11:23AM +0200, Michal Hocko wrote: > 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. 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. > 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. -- Mel Gorman SUSE Labs