linux-kernel - Re: [patch 1/3] memcg: prevent endless loop when charging huge pages

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Message-ID: <AANLkTikB+_Qgb0OA8mkEhftAvH3eZz_PCTqrzCoZUqEy@mail.gmail.com>
Date:	Tue, 1 Feb 2011 07:27:36 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	akpm@...ux-foundation.org, kamezawa.hiroyu@...fujitsu.com,
	nishimura@....nes.nec.co.jp, balbir@...ux.vnet.ibm.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] memcg: prevent endless loop when charging huge pages

On Mon, Jan 31, 2011 at 11:03 PM, Johannes Weiner <hannes@...xchg.org> wrote:
> The charging code can encounter a charge size that is bigger than a
> regular page in two situations: one is a batched charge to fill the
> per-cpu stocks, the other is a huge page charge.
>
> This code is distributed over two functions, however, and only the
> outer one is aware of huge pages.  In case the charging fails, the
> inner function will tell the outer function to retry if the charge
> size is bigger than regular pages--assuming batched charging is the
> only case.  And the outer function will retry forever charging a huge
> page.
>
> This patch makes sure the inner function can distinguish between batch
> charging and a single huge page charge.  It will only signal another
> attempt if batch charging failed, and go into regular reclaim when it
> is called on behalf of a huge page.
>
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Reviewed-by: Minchan Kim <minchan.kim@...il.com>

-- 
Kind regards,
Minchan Kim
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