linux-kernel - Re: [PATCH 0/2] Add support to aio ring pages migration

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Date:	Thu, 11 Jul 2013 18:11:28 +0800
From:	Gu Zheng <guz.fnst@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>,
	Benjamin LaHaise <bcrl@...ck.org>,
	Al Viro <viro@...iv.linux.org.uk>
CC:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	tangchen <tangchen@...fujitsu.com>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH 0/2] Add support to aio ring pages migration

ping...

On 07/08/2013 06:38 PM, Gu Zheng wrote:

> Currently aio ring pages use get_user_pages() to allocate pages from movable
> zone,as discussed in thread https://lkml.org/lkml/2012/11/29/69, it is easy to
> pin user pages for a long time, which is fatal for memory hotplug/remove framework.
> 
> As Mel Gorman suggested, "Implement a callback for migration to unpin pages,
> barrier operations until migration completes and pin the new pfns" can soloved
> this issue. And the best palce to hold the callbacks is address space operations
> which can be found via page->mapping.
> 
> But the current aio ring pages are anonymous pages, they don't have
> address_space_operations, so we use an anon inode file as the aio ring file to
> manage the aio ring pages, so that we can implement the callback and register it
> to page->mmapping->a_ops->migratepage.
> 
> But there's a ploblem that all files created by anon_inode_getfile() share the
> same inode, so mutil aio context will share the same aio ring pages, it'll lead
> to io events chaos. In order to solve this issus, we introduce a new fucntion
> anon_inode_getfile_private() which is samilar to anon_inode_getfile(), but each
> new file has its own anon inode.
> 
> This work is based on Benjamin's patch,
> http://www.spinics.net/lists/linux-fsdevel/msg66014.html
> 
> Gu Zheng (2):
>   fs/anon_inode: Introduce a new lib function
>     anon_inode_getfile_private()
>   fs/aio: Add support to aio ring pages migration
> 
>  fs/aio.c                    |  120 +++++++++++++++++++++++++++++++++++++++----
>  fs/anon_inodes.c            |   66 +++++++++++++++++++++++
>  include/linux/anon_inodes.h |    3 +
>  include/linux/migrate.h     |    3 +
>  mm/migrate.c                |    2 +-
>  5 files changed, 182 insertions(+), 12 deletions(-)
> 


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