From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S940116AbdEXMzR (ORCPT ); Wed, 24 May 2017 08:55:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:51806 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S937187AbdEXMzD (ORCPT ); Wed, 24 May 2017 08:55:03 -0400 Date: Wed, 24 May 2017 14:55:00 +0200 From: Michal Hocko To: Vlastimil Babka Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Andrea Arcangeli , Jerome Glisse , 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 Subject: Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline Message-ID: <20170524125500.GG14733@dhcp22.suse.cz> References: <20170524122411.25212-1-mhocko@kernel.org> <20170524122411.25212-2-mhocko@kernel.org> <467b4bcb-cc7e-a001-b35c-29d0ce29efee@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <467b4bcb-cc7e-a001-b35c-29d0ce29efee@suse.cz> 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 On Wed 24-05-17 14:44:34, Vlastimil Babka wrote: > On 05/24/2017 02:24 PM, Michal Hocko wrote: > > From: Michal Hocko > > > > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL > > memory") has added can_offline_normal which checks the amount of > > memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable. > > It disallows to offline memory if there is nothing left with a > > justification that "memory-management acts bad when we have nodes which > > is online but don't have any normal memory". > > > > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL > > memory") > > That's the same commit as above... one of them should be different? This used to be two different patches which I decided to fold together and I didn't realize that both online and offline paths were introduced by the same patch. [...] > Some editing issue? yes result of merging two commits. > Otherwise makes sense to me. > Acked-by: Vlastimil Babka Thanks! Updated version follows --- >>From 5196f9e206d780ac473075aa0ad88308409f5acb Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 23 May 2017 10:32:04 +0200 Subject: [PATCH] mm, memory_hotplug: drop artificial restriction on online/offline 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL memory") has introduced a restriction that every numa node has to have at least some memory in !movable zones before a first movable memory can be onlined if !CONFIG_MOVABLE_NODE. Likewise_offline_normal checks the amount of normal memory in !movable zones and it disallows to offline memory if there is no normal memory left with a justification that "memory-management acts bad when we have nodes which is online but don't have any normal memory". While it is true that not having _any_ memory for kernel allocations on a NUMA node is far from great and such a node would be quite subotimal because all kernel allocations will have to fallback to another NUMA node but there is no reason to disallow such a configuration in principle. Besides that there is not really a big difference to have one memblock for ZONE_NORMAL available or none. With 128MB size memblocks the system might trash on the kernel allocations requests anyway. It is really hard to draw a line on how much normal memory is really sufficient so we have to rely on administrator to configure system sanely therefore drop the artificial restriction and remove can_offline_normal and can_online_high_movable altogether. Acked-by: Acked-by: Vlastimil Babka Signed-off-by: Michal Hocko --- mm/memory_hotplug.c | 58 ----------------------------------------------------- 1 file changed, 58 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 599c675ad538..10052c2fd400 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -763,23 +763,6 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, return 0; } -#ifdef CONFIG_MOVABLE_NODE -/* - * When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have - * normal memory. - */ -static bool can_online_high_movable(int nid) -{ - return true; -} -#else /* CONFIG_MOVABLE_NODE */ -/* ensure every online node has NORMAL memory */ -static bool can_online_high_movable(int nid) -{ - return node_state(nid, N_NORMAL_MEMORY); -} -#endif /* CONFIG_MOVABLE_NODE */ - /* check which state of node_states will be changed when online memory */ static void node_states_check_changes_online(unsigned long nr_pages, struct zone *zone, struct memory_notify *arg) @@ -979,9 +962,6 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ if (!allow_online_pfn_range(nid, pfn, nr_pages, online_type)) return -EINVAL; - if (online_type == MMOP_ONLINE_MOVABLE && !can_online_high_movable(nid)) - return -EINVAL; - /* associate pfn range with the zone */ zone = move_pfn_range(online_type, nid, pfn, nr_pages); @@ -1579,41 +1559,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) return offlined; } -#ifdef CONFIG_MOVABLE_NODE -/* - * When CONFIG_MOVABLE_NODE, we permit offlining of a node which doesn't have - * normal memory. - */ -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages) -{ - return true; -} -#else /* CONFIG_MOVABLE_NODE */ -/* ensure the node has NORMAL memory if it is still online */ -static bool can_offline_normal(struct zone *zone, unsigned long nr_pages) -{ - struct pglist_data *pgdat = zone->zone_pgdat; - unsigned long present_pages = 0; - enum zone_type zt; - - for (zt = 0; zt <= ZONE_NORMAL; zt++) - present_pages += pgdat->node_zones[zt].present_pages; - - if (present_pages > nr_pages) - return true; - - present_pages = 0; - for (; zt <= ZONE_MOVABLE; zt++) - present_pages += pgdat->node_zones[zt].present_pages; - - /* - * we can't offline the last normal memory until all - * higher memory is offlined. - */ - return present_pages == 0; -} -#endif /* CONFIG_MOVABLE_NODE */ - static int __init cmdline_parse_movable_node(char *p) { #ifdef CONFIG_MOVABLE_NODE @@ -1741,9 +1686,6 @@ static int __ref __offline_pages(unsigned long start_pfn, node = zone_to_nid(zone); nr_pages = end_pfn - start_pfn; - if (zone_idx(zone) <= ZONE_NORMAL && !can_offline_normal(zone, nr_pages)) - return -EINVAL; - /* set above range as isolated */ ret = start_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE, true); -- 2.11.0 -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 59BFE6B02B4 for ; Wed, 24 May 2017 08:55:03 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id u96so15527920wrc.7 for ; Wed, 24 May 2017 05:55:03 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id i4si22577603edc.294.2017.05.24.05.55.01 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 24 May 2017 05:55:02 -0700 (PDT) Date: Wed, 24 May 2017 14:55:00 +0200 From: Michal Hocko Subject: Re: [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline Message-ID: <20170524125500.GG14733@dhcp22.suse.cz> References: <20170524122411.25212-1-mhocko@kernel.org> <20170524122411.25212-2-mhocko@kernel.org> <467b4bcb-cc7e-a001-b35c-29d0ce29efee@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <467b4bcb-cc7e-a001-b35c-29d0ce29efee@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Andrea Arcangeli , Jerome Glisse , 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 On Wed 24-05-17 14:44:34, Vlastimil Babka wrote: > On 05/24/2017 02:24 PM, Michal Hocko wrote: > > From: Michal Hocko > > > > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL > > memory") has added can_offline_normal which checks the amount of > > memory in !movable zones as long as CONFIG_MOVABLE_NODE is disable. > > It disallows to offline memory if there is nothing left with a > > justification that "memory-management acts bad when we have nodes which > > is online but don't have any normal memory". > > > > 74d42d8fe146 ("memory_hotplug: ensure every online node has NORMAL > > memory") > > That's the same commit as above... one of them should be different? This used to be two different patches which I decided to fold together and I didn't realize that both online and offline paths were introduced by the same patch. [...] > Some editing issue? yes result of merging two commits. > Otherwise makes sense to me. > Acked-by: Vlastimil Babka Thanks! Updated version follows ---