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From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
	Andrew Morton <akpm@linux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	qiuxishi@huawei.com, Igor Mammedov <imammedo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early
Date: Wed, 11 Oct 2017 13:24:15 +0200
Message-ID: <20171011112415.6hsudsrqhyuwjffx@dhcp22.suse.cz> (raw)
In-Reply-To: <c1b5f3cf-db9b-1cb8-dd0d-312940b7b953@suse.cz>

On Wed 11-10-17 13:17:13, Vlastimil Babka wrote:
> On 10/11/2017 10:13 AM, Michal Hocko wrote:
> > On Wed 11-10-17 10:04:39, Vlastimil Babka wrote:
> >> On 10/11/2017 08:51 AM, Michal Hocko wrote:
> > [...]
> >>> This is really strange! As you write in other email the page is
> >>> reserved. That means that some of the earlier checks 
> >>> 	if (zone_idx(zone) == ZONE_MOVABLE)
> >>> 		return false;
> >>> 	mt = get_pageblock_migratetype(page);
> >>> 	if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
> >>
> >> The MIGRATE_MOVABLE check is indeed bogus, because that doesn't
> >> guarantee there are no unmovable pages in the block (CMA block OTOH
> >> should be a guarantee).
> > 
> > OK, thanks for confirmation. I will remove the MIGRATE_MOVABLE check
> > here. Do you think it is worth removing CMA check as well? This is
> > merely an optimization AFAIU because we do not have to check the full
> > pageblockworth of pfns.
> 
> Actually, we should remove the CMA part as well. It's true that
> MIGRATE_CMA does guarantee that the *buddy allocator* won't allocate
> non-MOVABLE pages from the pageblock. But if the memory got allocated as
> an actual CMA allocation (alloc_contig...) it will almost certainly not
> be movable.

That was my suspicious. Thanks!
-- 
Michal Hocko
SUSE Labs

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Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-18  7:08 [PATCH v2 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-18  7:08 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko
2017-10-10 12:05   ` Michael Ellerman
2017-10-10 12:27     ` Michal Hocko
2017-10-11  2:37       ` Michael Ellerman
2017-10-11  5:19         ` Michael Ellerman
2017-10-11 14:05           ` Anshuman Khandual
2017-10-11 14:16             ` Michal Hocko
2017-10-11  6:51         ` Michal Hocko
2017-10-11  8:04           ` Vlastimil Babka
2017-10-11  8:13             ` Michal Hocko
2017-10-11 11:17               ` Vlastimil Babka
2017-10-11 11:24                 ` Michal Hocko [this message]
2017-10-13 11:42             ` Michael Ellerman
2017-10-13 11:58               ` Michal Hocko
2017-10-13 12:00                 ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Michal Hocko
2017-10-13 12:00                   ` [PATCH 2/2] mm, page_alloc: fail has_unmovable_pages when seeing reserved pages Michal Hocko
2017-10-13 12:04                     ` Vlastimil Babka
2017-10-13 12:07                       ` Michal Hocko
2017-10-17 13:03                         ` Vlastimil Babka
2017-10-17 11:41                   ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Michael Ellerman
2017-10-17 12:03                     ` Michal Hocko
2017-10-17 13:02                   ` Vlastimil Babka
2017-10-19  2:51                   ` Joonsoo Kim
2017-10-19  7:15                     ` Michal Hocko
2017-10-19  7:33                       ` Joonsoo Kim
2017-10-19  8:20                         ` Michal Hocko
2017-10-19 12:21                           ` Michal Hocko
2017-10-20  2:13                             ` Joonsoo Kim
2017-10-20  5:59                               ` Michal Hocko
2017-10-20  6:50                                 ` Joonsoo Kim
2017-10-20  7:02                                   ` Michal Hocko
2017-10-23  5:23                                     ` Joonsoo Kim
2017-10-23  8:10                                       ` Michal Hocko
2017-10-24  4:44                                         ` Joonsoo Kim
2017-10-24  7:44                                           ` Michal Hocko
2017-10-24  8:12                                           ` Vlastimil Babka
2017-10-24 12:25                                             ` Michal Hocko
2017-10-26  2:47                                             ` Joonsoo Kim
2017-10-26  7:41                                               ` Michal Hocko
2017-10-20  7:22                               ` Xishi Qiu
2017-10-20  8:17                                 ` Michal Hocko
2017-10-23  5:26                                   ` Joonsoo Kim
2017-10-26 13:04                             ` Vlastimil Babka
2017-10-26 13:59                             ` Michal Hocko
2017-09-18  7:08 ` [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko
  -- strict thread matches above, loose matches on Subject: below --
2017-09-04  8:21 [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-04  8:21 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko
2017-09-05  6:29   ` Anshuman Khandual
2017-09-05  7:13     ` Michal Hocko
2017-09-08 17:26   ` Vlastimil Babka
2017-09-11  8:17     ` Michal Hocko
2017-09-13 11:41       ` Vlastimil Babka
2017-09-13 12:10         ` Michal Hocko
2017-09-13 12:14           ` Michal Hocko
2017-09-13 12:19             ` Vlastimil Babka
2017-09-13 12:32               ` Michal Hocko

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