linux-kernel - Re: [BUG REPORT] [mm-hotplug, aio] aio ring

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Date:	Fri, 30 Nov 2012 11:39:40 +0800
From:	Lin Feng <linfeng@...fujitsu.com>
To:	Zach Brown <zab@...bo.net>
CC:	Andrew Morton <akpm@...ux-foundation.org>, viro@...iv.linux.org.uk,
	bcrl@...ck.org, kamezawa.hiroyu@...fujitsu.com, mhocko@...e.cz,
	hughd@...gle.com, cl@...ux.com, mgorman@...e.de,
	minchan@...nel.org, isimatu.yasuaki@...fujitsu.com,
	laijs@...fujitsu.com, wency@...fujitsu.com,
	tangchen@...fujitsu.com, linux-fsdevel@...r.kernel.org,
	linux-aio@...ck.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [BUG REPORT] [mm-hotplug, aio] aio ring_pages can't be offlined

Hi Zach,

Thanks for your advice. So agree, I will look into it to lead aio 
to use non-movable pages.


Thanks,
linfeng
On 11/30/2012 08:04 AM, Zach Brown wrote:
>> The best I can think of is to make changes in or around
>> get_user_pages(), to steal the pages from userspace and replace them
>> with non-movable ones before pinning them.  The performance cost of
>> something like this would surely be unacceptable for direct-io, but
>> maybe OK for the aio ring and futexes.
> 
> In the aio case it seems like it could be taught to populate the mapping
> with non-movable pages to begin with.  It's calling get_user_pages() a
> few lines after instantiating the mapping itself with do_mmap_pgoff().
> 
> - z
> 

-- 
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Lin Feng
Development Dept.I
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST) No. 6 Wenzhu Road,
Nanjing, 210012, China
PHONE：+86-25-86630566-8557 
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MAIL：linfeng@...fujitsu.com
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