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From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
	minchan.kim@gmail.com, kamezawa.hiroyu@jp.fujitsu.com,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Subject: Re: [PATCH v4] mm: add replace_page_cache_page() function
Date: Wed, 19 Jan 2011 09:27:33 +0900	[thread overview]
Message-ID: <20110119092733.4927f935.nishimura@mxp.nes.nec.co.jp> (raw)
In-Reply-To: <20110118152844.88cfdc2c.akpm@linux-foundation.org>

On Tue, 18 Jan 2011 15:28:44 -0800
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Tue, 18 Jan 2011 12:18:11 +0100
> Miklos Szeredi <miklos@szeredi.hu> wrote:
> 
> > +int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
> > +{
> > +	int error;
> > +	struct mem_cgroup *memcg = NULL;
> 
> I'm suspecting that the unneeded initialisation was added to suppress a
> warning?
> 
No.
It's necessary for mem_cgroup_{prepare|end}_migration().
mem_cgroup_prepare_migration() will return without doing anything in
"if (mem_cgroup_disabled()" case(iow, "memcg" is not overwritten),
but mem_cgroup_end_migration() depends on the value of "memcg" to decide
whether prepare_migration has succeeded or not.
This may not be a good implementation, but IMHO I'd like to to initialize
valuable before using it in general.

Thanks,
Daisuke Nishimura.

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  reply	other threads:[~2011-01-19  0:27 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-18 11:18 [PATCH v4] mm: add replace_page_cache_page() function Miklos Szeredi
2011-01-18 23:28 ` Andrew Morton
2011-01-19  0:27   ` Daisuke Nishimura [this message]
2011-01-19  0:41     ` Andrew Morton
2011-01-19  0:48     ` KAMEZAWA Hiroyuki
2011-01-19  1:11       ` nishimura
2011-01-19  1:23         ` KAMEZAWA Hiroyuki
2011-01-21  5:52           ` Daisuke Nishimura
2011-01-21  6:17             ` KAMEZAWA Hiroyuki
2011-01-19  0:33   ` KAMEZAWA Hiroyuki
2011-01-19  1:24   ` Minchan Kim
2011-01-19  1:48     ` Andrew Morton
2011-01-19  2:17       ` Minchan Kim
2011-09-08 23:52   ` Andrew Morton
2011-09-09  1:43     ` KAMEZAWA Hiroyuki
2011-01-19  1:17 ` Minchan Kim

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