From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@suse.com>, Laura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org
Subject: Re: [LSF/MM TOPIC] CMA and larger page sizes
Date: Thu, 12 Apr 2018 08:27:59 +0200 [thread overview]
Message-ID: <cca1f71a-3010-46db-231e-bcc0b0796ffd@suse.cz> (raw)
In-Reply-To: <20180412055122.GP23400@dhcp22.suse.cz>
On 04/12/2018 07:51 AM, Michal Hocko wrote:
> On Wed 11-04-18 18:06:59, Laura Abbott wrote:
>>
>> I took a look at this a little bit more and while it's true we don't
>> have the unmovable restriction anymore, CMA is still tied to the pageblock
>> size (512MB) because we still have MIGRATE_CMA. I guess making the
>> pageblock smaller seems like the most plausible approach?
>
> Maybe I am wrong but my take on what Joonsoo said is that we really do
> not have to care about page blocks and MIGRATE_CMA because GFP_MOVABLE
> can be allocated from that migrate type as it is by definition movable.
> The size of the page block shouldn't matter.
Agree, CMA itself doesn't need mark pageblocks with MIGRATE_CMA anymore.
The only user is now hardened usercopy via check_page_span() ->
is_migrate_cma_page(). If we could give up the CMA check there (or
recognize CMA differently?), MIGRATE_CMA could be removed completely,
together with the pageblock alignment code.
next prev parent reply other threads:[~2018-04-12 6:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-26 10:08 Laura Abbott
2018-01-26 17:25 ` Michal Hocko
2018-04-04 5:11 ` Joonsoo Kim
2018-04-11 19:55 ` Laura Abbott
2018-04-11 20:02 ` Vlastimil Babka
2018-04-12 1:06 ` Laura Abbott
2018-04-12 5:51 ` Michal Hocko
2018-04-12 6:27 ` Vlastimil Babka [this message]
2018-04-17 11:36 ` Michal Hocko
2018-04-17 15:01 ` Laura Abbott
2018-04-18 8:17 ` Michal Hocko
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