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From: "Huang, Ying" <ying.huang@intel.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	yang.shi@linux.alibaba.com, rientjes@google.com,
	dan.j.williams@intel.com, david@redhat.com, osalvador@suse.de,
	weixugc@google.com
Subject: Re: [PATCH 00/10] [v7][RESEND] Migrate Pages in lieu of discard
Date: Wed, 21 Apr 2021 10:39:09 +0800	[thread overview]
Message-ID: <87czuo1hv6.fsf@yhuang6-desk1.ccr.corp.intel.com> (raw)
In-Reply-To: <YHmm11fxEnxXAxas@dhcp22.suse.cz> (Michal Hocko's message of "Fri, 16 Apr 2021 17:02:23 +0200")

Michal Hocko <mhocko@suse.com> writes:

> On Fri 16-04-21 07:26:43, Dave Hansen wrote:
>> On 4/16/21 5:35 AM, Michal Hocko wrote:
>> > - Anonymous pages are bit tricky because they can be demoted even when
>> >   they cannot be reclaimed due to no (or no available) swap storage.
>> >   Unless I have missed something the second round will try to reclaim
>> >   them even the later is true and I am not sure this is completely OK.
>> 
>> What we want is something like this:
>> 
>> Swap Space / Demotion OK  -> Can Reclaim
>> Swap Space / Demotion Off -> Can Reclaim
>> Swap Full  / Demotion OK  -> Can Reclaim
>> Swap Full  / Demotion Off -> No Reclaim
>> 
>> I *think* that's what can_reclaim_anon_pages() ends up doing.  Maybe I'm
>> misunderstanding what you are referring to, though.  By "second round"
>> did you mean when we do reclaim on a node which is a terminal node?
>
> No, I mean the migration failure case where you splice back to the page
> list to reclaim. In that round you do not demote and want to reclaim.
> But a lack of swap space will make that page unreclaimable. I suspect
> this would just work out fine but I am not sure from the top of my head.

I have tested this via injecting some migration errors (returning 0 from
demote_page_list() before migration) on a system without swap.  The
system can still work properly.  In ftrace, I can find add_to_swap() are
called much more times, and it can deal with the situation where the
swap space isn't available.

Best Regards,
Huang, Ying

  reply	other threads:[~2021-04-21  2:39 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 18:32 [PATCH 00/10] [v7][RESEND] Migrate Pages in lieu of discard Dave Hansen
2021-04-01 18:32 ` [PATCH 01/10] mm/numa: node demotion data structure and lookup Dave Hansen
2021-04-08  8:03   ` Oscar Salvador
2021-04-08 21:29     ` Dave Hansen
2021-04-09  5:32   ` Wei Xu
2021-04-01 18:32 ` [PATCH 02/10] mm/numa: automatically generate node migration order Dave Hansen
2021-04-08  8:26   ` Oscar Salvador
2021-04-08 21:51     ` Dave Hansen
2021-04-09  8:17       ` Oscar Salvador
2021-04-10  3:07   ` Wei Xu
2021-04-14  8:08     ` Oscar Salvador
2021-04-14  8:11       ` Oscar Salvador
2021-04-14  8:12       ` David Hildenbrand
2021-04-14  8:14         ` Oscar Salvador
2021-04-14  8:20           ` David Hildenbrand
2021-04-15  4:07       ` Wei Xu
2021-04-15 15:35         ` Dave Hansen
2021-04-15 20:25           ` Wei Xu
2021-04-01 18:32 ` [PATCH 03/10] mm/migrate: update node demotion order during on hotplug events Dave Hansen
2021-04-08  9:52   ` Oscar Salvador
2021-04-09 10:14     ` Oscar Salvador
2021-04-09 10:15       ` Oscar Salvador
2021-04-09 18:59       ` David Hildenbrand
2021-04-12  7:19         ` Oscar Salvador
2021-04-12  9:19           ` David Hildenbrand
2021-04-01 18:32 ` [PATCH 04/10] mm/migrate: make migrate_pages() return nr_succeeded Dave Hansen
2021-04-01 22:39   ` Wei Xu
     [not found]   ` <CAAPL-u-o-M2T25xBtSoipYjUnu+3aJNcJ9uS84yKaAnbrXpefw@mail.gmail.com>
2021-04-01 23:21     ` Dave Hansen
2021-04-08 10:14   ` Oscar Salvador
2021-04-08 17:26     ` Yang Shi
2021-04-08 18:17       ` Oscar Salvador
2021-04-08 18:21         ` Oscar Salvador
2021-04-08 20:40         ` Yang Shi
2021-04-09  5:06           ` Oscar Salvador
2021-04-09  5:43             ` Wei Xu
2021-04-09 15:43             ` Yang Shi
2021-04-09 15:50         ` Dave Hansen
2021-04-09 18:47           ` Wei Xu
2021-04-09 20:10           ` Yang Shi
2021-04-01 18:32 ` [PATCH 05/10] mm/migrate: demote pages during reclaim Dave Hansen
2021-04-01 20:01   ` Yang Shi
2021-04-01 22:58     ` Dave Hansen
2021-04-08 10:47   ` Oscar Salvador
2021-04-10  3:35   ` Wei Xu
2021-04-01 18:32 ` [PATCH 06/10] mm/vmscan: add page demotion counter Dave Hansen
2021-04-10  3:40   ` Wei Xu
2021-04-01 18:32 ` [PATCH 07/10] mm/vmscan: add helper for querying ability to age anonymous pages Dave Hansen
2021-04-07 18:40   ` Wei Xu
2021-04-09  8:31     ` Oscar Salvador
2021-04-01 18:32 ` [PATCH 08/10] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2021-04-02  0:55   ` Wei Xu
2021-04-01 18:32 ` [PATCH 09/10] mm/vmscan: never demote for memcg reclaim Dave Hansen
2021-04-02  0:18   ` Wei Xu
2021-04-01 18:32 ` [PATCH 10/10] mm/migrate: new zone_reclaim_mode to enable reclaim migration Dave Hansen
2021-04-01 20:06   ` Yang Shi
2021-04-10  4:10   ` Wei Xu
2021-04-16 12:35 ` [PATCH 00/10] [v7][RESEND] Migrate Pages in lieu of discard Michal Hocko
2021-04-16 14:26   ` Dave Hansen
2021-04-16 15:02     ` Michal Hocko
2021-04-21  2:39       ` Huang, Ying [this message]
2021-05-07  6:14       ` Huang, Ying
2021-06-11  5:50       ` Huang, Ying

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