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From: Michal Hocko <mhocko@kernel.org>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>,
	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>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages
Date: Tue, 17 Oct 2017 14:03:18 +0200
Message-ID: <20171017120318.rers7zga3cnirt4i@dhcp22.suse.cz> (raw)
In-Reply-To: <871sm2j92j.fsf@concordia.ellerman.id.au>

On Tue 17-10-17 22:41:08, Michael Ellerman wrote:
> Michal Hocko <mhocko@kernel.org> writes:
> 
> > From: Michal Hocko <mhocko@suse.com>
> >
> > Michael has noticed that the memory offline tries to migrate kernel code
> > pages when doing
> >  echo 0 > /sys/devices/system/memory/memory0/online
> >
> > The current implementation will fail the operation after several failed
> > page migration attempts but we shouldn't even attempt to migrate
> > that memory and fail right away because this memory is clearly not
> > migrateable. This will become a real problem when we drop the retry loop
> > counter resp. timeout.
> >
> > The real problem is in has_unmovable_pages in fact. We should fail if
> > there are any non migrateable pages in the area. In orther to guarantee
> > that remove the migrate type checks because MIGRATE_MOVABLE is not
> > guaranteed to contain only migrateable pages. It is merely a heuristic.
> > Similarly MIGRATE_CMA does guarantee that the page allocator doesn't
> > allocate any non-migrateable pages from the block but CMA allocations
> > themselves are unlikely to migrateable. Therefore remove both checks.
> >
> > Reported-by: Michael Ellerman <mpe@ellerman.id.au>
> > Signed-off-by: Michal Hocko <mhocko@suse.com>
> 
> Thanks, that works for me.
> 
> Tested-by: Michael Ellerman <mpe@ellerman.id.au>

Thanks a lot Michael!

Andrew, could you add these two patches and merge them before
mm-memory_hotplug-do-not-fail-offlining-too-early.patch? Or should I
rather repost the full series (including 2 already merged patches?
again?
-- 
Michal Hocko
SUSE Labs

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  reply index

Thread overview: 51+ 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
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 [this message]
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
     [not found] <AM3PR04MB14892A9D6D2FBCE21B8C1F0FF12B0@AM3PR04MB1489.eurprd04.prod.outlook.com>
2017-11-13  7:33 ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Ran Wang
2017-11-13 11:02   ` Michal Hocko
2017-11-14  6:10     ` Ran Wang
2017-11-14  7:06       ` Michal Hocko
2017-11-14  7:45         ` Ran Wang

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