linux-kernel - Re: [PATCH 2/2] fs/aio.c: use get_user_pages_non_movable() to pin ring pages when support memory hotremove

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Message-ID: <51109352.9070401@cn.fujitsu.com>
Date:	Tue, 05 Feb 2013 13:06:26 +0800
From:	Lin Feng <linfeng@...fujitsu.com>
To:	Jeff Moyer <jmoyer@...hat.com>
CC:	akpm@...ux-foundation.org, mgorman@...e.de, bcrl@...ck.org,
	viro@...iv.linux.org.uk, khlebnikov@...nvz.org, walken@...gle.com,
	kamezawa.hiroyu@...fujitsu.com, minchan@...nel.org,
	riel@...hat.com, rientjes@...gle.com,
	isimatu.yasuaki@...fujitsu.com, wency@...fujitsu.com,
	laijs@...fujitsu.com, jiang.liu@...wei.com, linux-mm@...ck.org,
	linux-aio@...ck.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, Tang chen <tangchen@...fujitsu.com>,
	Gu Zheng <guz.fnst@...fujitsu.com>
Subject: Re: [PATCH 2/2] fs/aio.c: use get_user_pages_non_movable() to pin
 ring pages when support memory hotremove

Hi Jeff,

On 02/04/2013 11:18 PM, Jeff Moyer wrote:
>> ---
>>  fs/aio.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/fs/aio.c b/fs/aio.c
>> index 71f613c..0e9b30a 100644
>> --- a/fs/aio.c
>> +++ b/fs/aio.c
>> @@ -138,9 +138,15 @@ static int aio_setup_ring(struct kioctx *ctx)
>>  	}
>>  
>>  	dprintk("mmap address: 0x%08lx\n", info->mmap_base);
>> +#ifdef CONFIG_MEMORY_HOTREMOVE
>> +	info->nr_pages = get_user_pages_non_movable(current, ctx->mm,
>> +					info->mmap_base, nr_pages,
>> +					1, 0, info->ring_pages, NULL);
>> +#else
>>  	info->nr_pages = get_user_pages(current, ctx->mm,
>>  					info->mmap_base, nr_pages, 
>>  					1, 0, info->ring_pages, NULL);
>> +#endif
> 
> Can't you hide this in your 1/1 patch, by providing this function as
> just a static inline wrapper around get_user_pages when
> CONFIG_MEMORY_HOTREMOVE is not enabled?
Good idea, it makes the callers more neatly :)

thanks,
linfeng
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