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From: Michal Hocko <mhocko@kernel.org>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: linux-mm@kvack.org, Michael Ellerman <mpe@ellerman.id.au>,
	Vlastimil Babka <vbabka@suse.cz>,
	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>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages
Date: Thu, 19 Oct 2017 14:21:18 +0200
Message-ID: <20171019122118.y6cndierwl2vnguj@dhcp22.suse.cz> (raw)
In-Reply-To: <20171019082041.5zudpqacaxjhe4gw@dhcp22.suse.cz>

On Thu 19-10-17 10:20:41, Michal Hocko wrote:
> On Thu 19-10-17 16:33:56, Joonsoo Kim wrote:
> > On Thu, Oct 19, 2017 at 09:15:03AM +0200, Michal Hocko wrote:
> > > On Thu 19-10-17 11:51:11, Joonsoo Kim wrote:
> [...]
> > > > Hello,
> > > > 
> > > > This patch will break the CMA user. As you mentioned, CMA allocation
> > > > itself isn't migrateable. So, after a single page is allocated through
> > > > CMA allocation, has_unmovable_pages() will return true for this
> > > > pageblock. Then, futher CMA allocation request to this pageblock will
> > > > fail because it requires isolating the pageblock.
> > > 
> > > Hmm, does this mean that the CMA allocation path depends on
> > > has_unmovable_pages to return false here even though the memory is not
> > > movable? This sounds really strange to me and kind of abuse of this
> > 
> > Your understanding is correct. Perhaps, abuse or wrong function name.
> >
> > > function. Which path is that? Can we do the migrate type test theres?
> > 
> > alloc_contig_range() -> start_isolate_page_range() ->
> > set_migratetype_isolate() -> has_unmovable_pages()
> 
> I see. It seems that the CMA and memory hotplug have a very different
> view on what should happen during isolation.
>  
> > We can add one argument, 'XXX' to set_migratetype_isolate() and change
> > it to check migrate type rather than has_unmovable_pages() if 'XXX' is
> > specified.
> 
> Can we use the migratetype argument and do the special thing for
> MIGRATE_CMA? Like the following diff?

And with the full changelog.
---

  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
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 [this message]
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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