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[195.135.221.2]) by mx.google.com with ESMTP id r43si287564eda.124.2019.03.13.00.52.17 for ; Wed, 13 Mar 2019 00:52:17 -0700 (PDT) Received-SPF: pass (google.com: domain of osalvador@suse.de designates 195.135.221.2 as permitted sender) client-ip=195.135.221.2; Authentication-Results: mx.google.com; spf=pass (google.com: domain of osalvador@suse.de designates 195.135.221.2 as permitted sender) smtp.mailfrom=osalvador@suse.de Received: by suse.de (Postfix, from userid 1000) id AB5F84552; Wed, 13 Mar 2019 08:52:16 +0100 (CET) Date: Wed, 13 Mar 2019 08:52:16 +0100 From: Oscar Salvador To: Qian Cai Cc: akpm@linux-foundation.org, mhocko@kernel.org, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/hotplug: fix offline undo_isolate_page_range() Message-ID: <20190313075212.wc3pbwixx3ppwxua@d104.suse.de> References: <20190313014216.36782-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190313014216.36782-1-cai@lca.pw> User-Agent: NeoMutt/20170421 (1.8.2) X-Bogosity: Ham, tests=bogofilter, spamicity=0.005248, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 12, 2019 at 09:42:16PM -0400, Qian Cai wrote: > + > + /* > + * Onlining will reset pagetype flags and makes migrate type > + * MOVABLE, so just need to decrease the number of isolated > + * pageblocks zone counter here. > + */ > + for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { > + int i; > + > + for (i = 0; i < pageblock_nr_pages; i++) > + if (pfn_valid_within(pfn + i)) { > + zone->nr_isolate_pageblock--; > + break; > + } > + } > + I do not really like this. I first thought about saving the value before entering start_isolate_page_range, but that could race with alloc_contig_range for instance. So, why not make start_isolate_page_range to return the actual number of isolated pageblocks? Sure, that would mean to change a bit how we threat its return code, but I think that it is pretty simple. In that way, we would only have to substract the value start_isolate_page_range gave us at the end of __offline__pages() to set nr_isolate_pageblock back to its original value. -- Oscar Salvador SUSE L3