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From: Dave Hansen <dave.hansen@intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>,
	Jerome Glisse <jglisse@redhat.com>
Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [LSF/MM TOPIC] Un-addressable device memory and block/fs implications
Date: Tue, 13 Dec 2016 12:27:53 -0800	[thread overview]
Message-ID: <4878d525-70cd-fa0e-b17f-4222c3166e74@intel.com> (raw)
In-Reply-To: <1481659264.2473.59.camel@HansenPartnership.com>

On 12/13/2016 12:01 PM, James Bottomley wrote:
>> > Second aspect is that even if memory i am dealing with is un
>> > -addressable i still have struct page for it and i want to be able to 
>> > use regular page migration.
> Tmem keeps a struct page ... what's the problem with page migration?
> the fact that tmem locks the page when it's not addressable and you
> want to be able to migrate the page even when it's not addressable?

Hi James,

Why do you say that tmem keeps a 'struct page'?  For instance, its
->put_page operation _takes_ a 'struct page', but that's in the
delete_from_page_cache() path where the page's last reference has been
dropped and it is about to go away.  The role of 'struct page' here is
just to help create a key so that tmem can find the contents later
*without* the original 'struct page'.

Jerome's pages here are a new class of half-crippled 'struct page' which
support more VM features than ZONE_DEVICE pages, but not quite a full
feature set.  It supports (and needs to support) a heck of a lot more VM
features than memory in tmem would, though.


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  parent reply	other threads:[~2016-12-13 20:27 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-13 18:15 Jerome Glisse
2016-12-13 18:20 ` James Bottomley
2016-12-13 18:55   ` Jerome Glisse
2016-12-13 20:01     ` James Bottomley
2016-12-13 20:22       ` Jerome Glisse
2016-12-13 20:27       ` Dave Hansen [this message]
2016-12-13 20:15 ` Dave Chinner
2016-12-13 20:31   ` Jerome Glisse
2016-12-13 21:10     ` Dave Chinner
2016-12-13 21:24       ` Jerome Glisse
2016-12-13 22:08         ` Dave Hansen
2016-12-13 23:02           ` Jerome Glisse
2016-12-13 22:13         ` Dave Chinner
2016-12-13 22:55           ` Jerome Glisse
2016-12-14  0:14             ` Dave Chinner
2016-12-14  1:07               ` Jerome Glisse
2016-12-14  4:23                 ` Dave Chinner
2016-12-14 16:35                   ` Jerome Glisse
2016-12-14 11:13         ` [Lsf-pc] " Jan Kara
2016-12-14 17:15           ` Jerome Glisse
2016-12-15 16:19             ` Jan Kara
2016-12-15 19:14               ` Jerome Glisse
2016-12-16  8:14                 ` Jan Kara
2016-12-16  3:10               ` Aneesh Kumar K.V
2016-12-19  8:46                 ` Jan Kara
2016-12-19 17:00           ` Aneesh Kumar K.V
2016-12-14  3:55 ` Balbir Singh
2016-12-16  3:14 ` [LSF/MM ATTEND] " Aneesh Kumar K.V
2017-01-16 12:04   ` Anshuman Khandual
2017-01-16 23:15     ` John Hubbard
2017-01-18 11:00   ` [Lsf-pc] " Jan Kara

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