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 2BED9C4708C for ; Fri, 28 May 2021 10:09:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FD20611C2 for ; Fri, 28 May 2021 10:09:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236441AbhE1KK6 (ORCPT ); Fri, 28 May 2021 06:10:58 -0400 Received: from outbound-smtp02.blacknight.com ([81.17.249.8]:44747 "EHLO outbound-smtp02.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236396AbhE1KKz (ORCPT ); Fri, 28 May 2021 06:10:55 -0400 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp02.blacknight.com (Postfix) with ESMTPS id D538EBAB09 for ; Fri, 28 May 2021 11:09:19 +0100 (IST) Received: (qmail 28010 invoked from network); 28 May 2021 10:09:19 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.23.168]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 28 May 2021 10:09:19 -0000 Date: Fri, 28 May 2021 11:09:18 +0100 From: Mel Gorman To: David Hildenbrand Cc: Dave Hansen , Andrew Morton , Hillf Danton , Dave Hansen , Vlastimil Babka , Michal Hocko , LKML , Linux-MM , "Tang, Feng" Subject: Re: [PATCH 0/6 v2] Calculate pcp->high based on zone sizes and active CPUs Message-ID: <20210528100918.GM30378@techsingularity.net> References: <20210525080119.5455-1-mgorman@techsingularity.net> <7177f59b-dc05-daff-7dc6-5815b539a790@intel.com> <20210528085545.GJ30378@techsingularity.net> <54ff0363-2f39-71d1-e26c-962c3fddedae@redhat.com> <20210528094949.GL30378@techsingularity.net> <6c189def-11cc-80db-0fde-56aa506cfdea@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <6c189def-11cc-80db-0fde-56aa506cfdea@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 28, 2021 at 11:52:53AM +0200, David Hildenbrand wrote: > > > "Disable pcplists so that page isolation cannot race with freeing > > > in a way that pages from isolated pageblock are left on pcplists." > > > > > > Guess we'd then want to move the draining before start_isolate_page_range() > > > in alloc_contig_range(). > > > > > > > Or instead of draining, validate the PFN range in alloc_contig_range > > is within the same zone and if so, call zone_pcp_disable() before > > start_isolate_page_range and enable after __alloc_contig_migrate_range. > > > > We require the caller to only pass a range within a single zone, so that > should be fine. > > The only ugly thing about zone_pcp_disable() is > mutex_lock(&pcp_batch_high_lock) which would serialize all > alloc_contig_range() and even with offline_pages(). > True so it would have to be accessed if that is bad or not. If racing against offline_pages, memory is potentially being offlined in the target zone which may cause allocation failure. If racing with other alloc_contig_range calls, the two callers are potentially racing to isolate and allocate the same range. The arguement could be made that alloc_contig_ranges should be serialised within one zone to improve the allocation success rate at the potential cost of allocation latency. -- Mel Gorman SUSE Labs