linux-kernel - Re: [BUGFIX][PATCH 1/4] memcg: fix limit estimation at reclaim for hugepage

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Date:	Fri, 28 Jan 2011 17:37:29 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hannes@...xchg.org" <hannes@...xchg.org>,
	"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>
Subject: Re: [BUGFIX][PATCH 1/4] memcg: fix limit estimation at reclaim for hugepage

On Fri, Jan 28, 2011 at 5:24 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@...fujitsu.com> wrote:
> On Fri, 28 Jan 2011 17:04:16 +0900
> Minchan Kim <minchan.kim@...il.com> wrote:
>
>> Hi Kame,
>>
>> On Fri, Jan 28, 2011 at 1:58 PM, KAMEZAWA Hiroyuki
>> <kamezawa.hiroyu@...fujitsu.com> wrote:
>> > How about this ?
>> > ==
>> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>> >
>> > Current memory cgroup's code tends to assume page_size == PAGE_SIZE
>> > and arrangement for THP is not enough yet.
>> >
>> > This is one of fixes for supporing THP. This adds
>> > mem_cgroup_check_margin() and checks whether there are required amount of
>> > free resource after memory reclaim. By this, THP page allocation
>> > can know whether it really succeeded or not and avoid infinite-loop
>> > and hangup.
>> >
>> > Total fixes for do_charge()/reclaim memory will follow this patch.
>>
>> If this patch is only related to THP, I think patch order isn't good.
>> Before applying [2/4], huge page allocation will retry without
>> reclaiming and loop forever by below part.
>>
>> @@ -1854,9 +1858,6 @@ static int __mem_cgroup_do_charge(struct
>>       } else
>>               mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
>>
>> -     if (csize > PAGE_SIZE) /* change csize and retry */
>> -             return CHARGE_RETRY;
>> -
>>       if (!(gfp_mask & __GFP_WAIT))
>>               return CHARGE_WOULDBLOCK;
>>
>> Am I missing something?
>>
>
> You're right. But
>  - This patch oder doesn't affect bi-sect of the bug. because
>   2 bugs seems to be the same.
>  - This patch implements a leaf function for the real fix.
>
> Then, I think patch order is not problem here.
>
> Thank you for pointing out.

Okay. I understand Hannes and your opinion.
In my opinion, my suggestion can enhance the patch readability in this
series as just only my viewpoint. :)
Anyway, I don't mind it.

Reviewed-by: Minchan Kim <minchan.kim@...il.com>

Thanks!!

>
> Thanks,
> -Kame
>
>
>
>
>



-- 
Kind regards,
Minchan Kim
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