Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751795AbdCPIzl (ORCPT ); Thu, 16 Mar 2017 04:55:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:57884 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751489AbdCPIy7 (ORCPT ); Thu, 16 Mar 2017 04:54:59 -0400 Date: Thu, 16 Mar 2017 09:54:04 +0100 From: Michal Hocko To: "Kani, Toshimitsu" Cc: "linux-mm@kvack.org" , "zhenzhang.zhang@huawei.com" , "tangchen@cn.fujitsu.com" , "arbab@linux.vnet.ibm.com" , "vkuznets@redhat.com" , "linux-kernel@vger.kernel.org" , "daniel.kiper@oracle.com" , "xieyisheng1@huawei.com" , "iamjoonsoo.kim@lge.com" , "qiuxishi@huawei.com" , "yasu.isimatu@gmail.com" , "akpm@linux-foundation.org" , "aarcange@redhat.com" , "vbabka@suse.cz" , "imammedo@redhat.com" , "rientjes@google.com" , "mgorman@suse.de" , "ak@linux.intel.com" , "slaoub@gmail.com" Subject: Re: [RFC PATCH] rework memory hotplug onlining Message-ID: <20170316085404.GE30501@dhcp22.suse.cz> References: <20170315091347.GA32626@dhcp22.suse.cz> <1489622542.9118.8.camel@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1489622542.9118.8.camel@hpe.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1968 Lines: 54 On Wed 15-03-17 23:08:14, Kani, Toshimitsu wrote: > On Wed, 2017-03-15 at 10:13 +0100, Michal Hocko wrote: > : > > @@ -388,39 +389,44 @@ static ssize_t show_valid_zones(struct device > > *dev, > > ? struct device_attribute *attr, char > > *buf) > > ?{ > > ? struct memory_block *mem = to_memory_block(dev); > > - unsigned long start_pfn, end_pfn; > > - unsigned long valid_start, valid_end, valid_pages; > > - unsigned long nr_pages = PAGES_PER_SECTION * > > sections_per_block; > > + unsigned long start_pfn, nr_pages; > > + bool append = false; > > ? struct zone *zone; > > - int zone_shift = 0; > > + int nid; > > ? > > ? start_pfn = section_nr_to_pfn(mem->start_section_nr); > > - end_pfn = start_pfn + nr_pages; > > + zone = page_zone(pfn_to_page(start_pfn)); > > + nr_pages = PAGES_PER_SECTION * sections_per_block; > > ? > > - /* The block contains more than one zone can not be > > offlined. */ > > - if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, > > &valid_end)) > > + /* > > + ?* The block contains more than one zone can not be > > offlined. > > + ?* This can happen e.g. for ZONE_DMA and ZONE_DMA32 > > + ?*/ > > + if (!test_pages_in_a_zone(start_pfn, start_pfn + nr_pages, > > NULL, NULL)) > > ? return sprintf(buf, "none\n"); > > ? > > - zone = page_zone(pfn_to_page(valid_start)); > > Please do not remove the fix made in a96dfddbcc043. zone needs to be > set from valid_start, not from start_pfn. Thanks for pointing this out. I was scratching my head about this part but was too tired from previous git archeology so I didn't check the history of this particular part. I will restore the original behavior but before I do that I am really curious whether partial memblocks are even supported for onlining. Maybe I am missing something but I do not see any explicit checks for NULL struct page when we set zone boundaries or online a memblock. Is it possible those memblocks are just never hotplugable? -- Michal Hocko SUSE Labs