From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753479AbdGSNQA (ORCPT ); Wed, 19 Jul 2017 09:16:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:54630 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751991AbdGSNP7 (ORCPT ); Wed, 19 Jul 2017 09:15:59 -0400 Subject: Re: [PATCH 2/9] mm, page_alloc: remove boot pageset initialization from memory hotplug To: Michal Hocko , linux-mm@kvack.org Cc: Andrew Morton , Mel Gorman , Johannes Weiner , LKML , Michal Hocko References: <20170714080006.7250-1-mhocko@kernel.org> <20170714080006.7250-3-mhocko@kernel.org> From: Vlastimil Babka Message-ID: <0a8dcf64-b170-e6db-8ce5-0b9a5327785b@suse.cz> Date: Wed, 19 Jul 2017 15:15:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170714080006.7250-3-mhocko@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/14/2017 09:59 AM, Michal Hocko wrote: > From: Michal Hocko > > boot_pageset is a boot time hack which gets superseded by normal > pagesets later in the boot process. It makes zero sense to reinitialize > it again and again during memory hotplug. > > Signed-off-by: Michal Hocko Acked-by: Vlastimil Babka > --- > mm/page_alloc.c | 38 +++++++++++++++++++++----------------- > 1 file changed, 21 insertions(+), 17 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d9f4ea057e74..7746824a425d 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5098,23 +5098,8 @@ static int __build_all_zonelists(void *data) > } > } > > - /* > - * Initialize the boot_pagesets that are going to be used > - * for bootstrapping processors. The real pagesets for > - * each zone will be allocated later when the per cpu > - * allocator is available. > - * > - * boot_pagesets are used also for bootstrapping offline > - * cpus if the system is already booted because the pagesets > - * are needed to initialize allocators on a specific cpu too. > - * F.e. the percpu allocator needs the page allocator which > - * needs the percpu allocator in order to allocate its pagesets > - * (a chicken-egg dilemma). > - */ > - for_each_possible_cpu(cpu) { > - setup_pageset(&per_cpu(boot_pageset, cpu), 0); > - > #ifdef CONFIG_HAVE_MEMORYLESS_NODES > + for_each_possible_cpu(cpu) { > /* > * We now know the "local memory node" for each node-- > * i.e., the node of the first zone in the generic zonelist. > @@ -5125,8 +5110,8 @@ static int __build_all_zonelists(void *data) > */ > if (cpu_online(cpu)) > set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu))); > -#endif > } > +#endif > > return 0; > } > @@ -5134,7 +5119,26 @@ static int __build_all_zonelists(void *data) > static noinline void __init > build_all_zonelists_init(void) > { > + int cpu; > + > __build_all_zonelists(NULL); > + > + /* > + * Initialize the boot_pagesets that are going to be used > + * for bootstrapping processors. The real pagesets for > + * each zone will be allocated later when the per cpu > + * allocator is available. > + * > + * boot_pagesets are used also for bootstrapping offline > + * cpus if the system is already booted because the pagesets > + * are needed to initialize allocators on a specific cpu too. > + * F.e. the percpu allocator needs the page allocator which > + * needs the percpu allocator in order to allocate its pagesets > + * (a chicken-egg dilemma). > + */ > + for_each_possible_cpu(cpu) > + setup_pageset(&per_cpu(boot_pageset, cpu), 0); > + > mminit_verify_zonelist(); > cpuset_init_current_mems_allowed(); > } >