From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752290AbdDJQUM (ORCPT ); Mon, 10 Apr 2017 12:20:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48866 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514AbdDJQUL (ORCPT ); Mon, 10 Apr 2017 12:20:11 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com A1FBC787E7 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jglisse@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com A1FBC787E7 Date: Mon, 10 Apr 2017 12:20:02 -0400 From: Jerome Glisse To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Reza Arbab , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Andi Kleen , David Rientjes , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko , Dan Williams Subject: Re: [PATCH 4/9] mm, memory_hotplug: get rid of is_zone_device_section Message-ID: <20170410162002.GA31356@redhat.com> References: <20170410110351.12215-1-mhocko@kernel.org> <20170410110351.12215-5-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170410110351.12215-5-mhocko@kernel.org> User-Agent: Mutt/1.7.1 (2016-10-04) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 10 Apr 2017 16:20:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 10, 2017 at 01:03:46PM +0200, Michal Hocko wrote: > From: Michal Hocko > > device memory hotplug hooks into regular memory hotplug only half way. > It needs memory sections to track struct pages but there is no > need/desire to associate those sections with memory blocks and export > them to the userspace via sysfs because they cannot be onlined anyway. > > This is currently expressed by for_device argument to arch_add_memory > which then makes sure to associate the given memory range with > ZONE_DEVICE. register_new_memory then relies on is_zone_device_section > to distinguish special memory hotplug from the regular one. While this > works now, later patches in this series want to move __add_zone outside > of arch_add_memory path so we have to come up with something else. > > Add want_memblock down the __add_pages path and use it to control > whether the section->memblock association should be done. arch_add_memory > then just trivially want memblock for everything but for_device hotplug. > > remove_memory_section doesn't need is_zone_device_section either. We can > simply skip all the memblock specific cleanup if there is no memblock > for the given section. > > This shouldn't introduce any functional change. > > Cc: Dan Williams > Signed-off-by: Michal Hocko > --- [...] > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 342332f29364..1570b3eea493 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -493,7 +493,7 @@ static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn) > } > > static int __meminit __add_section(int nid, struct zone *zone, > - unsigned long phys_start_pfn) > + unsigned long phys_start_pfn, bool want_memblock) > { > int ret; > > @@ -510,7 +510,10 @@ static int __meminit __add_section(int nid, struct zone *zone, > if (ret < 0) > return ret; > > - return register_new_memory(nid, __pfn_to_section(phys_start_pfn)); > + if (want_memblock) > + ret = register_new_memory(nid, __pfn_to_section(phys_start_pfn)); > + > + return ret; > } The above is wrong for ZONE_DEVICE sparse_add_one_section() will return a positive value (on success) thus ret > 0 and other function in the hotplug path will interpret positive value as an error. I suggest something like: if (!want_memblock) return 0; return register_new_memory(nid, __pfn_to_section(phys_start_pfn)); } instead (also avoid a > 80 columns warning message). Cheers, Jérôme