Message-ID: <51DE84D0.2000209@cn.fujitsu.com>
Date: Thu, 11 Jul 2013 18:11:28 +0800
From: Gu Zheng <guz.fnst@cn.fujitsu.com>
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To: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mgorman@suse.de>,
        Benjamin LaHaise <bcrl@kvack.org>, Al Viro <viro@zeniv.linux.org.uk>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        tangchen <tangchen@cn.fujitsu.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>, linux-mm@kvack.org
Subject: Re: [PATCH 0/2] Add support to aio ring pages migration
References: <51DA96BC.1060701@cn.fujitsu.com>
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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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