Subject: Re: [PATCH 1/7] mm: memcontrol: charge swap to cgroup2
To: Johannes Weiner <hannes@cmpxchg.org>
References: <cover.1449742560.git.vdavydov@virtuozzo.com>
 <265d8fe623ed2773d69a26d302eb31e335377c77.1449742560.git.vdavydov@virtuozzo.com>
 <20151214153037.GB4339@dhcp22.suse.cz> <20151214194258.GH28521@esperanza>
 <566F8781.80108@jp.fujitsu.com> <20151215145011.GA20355@cmpxchg.org>
 <5670D806.60408@jp.fujitsu.com> <20151216110912.GA29816@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>,
        Michal Hocko <mhocko@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Message-ID: <56722203.5030604@jp.fujitsu.com>
Date: Thu, 17 Dec 2015 11:46:27 +0900
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On 2015/12/16 20:09, Johannes Weiner wrote:
> On Wed, Dec 16, 2015 at 12:18:30PM +0900, Kamezawa Hiroyuki wrote:
>> Hmm, my requests are
>>   - set the same capabilities as mlock() to set swap.limit=0
>
> Setting swap.max is already privileged operation.
>
Sure.

>>   - swap-full notification via vmpressure or something mechanism.
>
> Why?
>

I think it's a sign of unhealthy condition, starting file cache drop rate to rise.
But I forgot that there are resource threshold notifier already. Does the notifier work
for swap.usage ?

>>   - OOM-Killer's available memory calculation may be corrupted, please check.
>
> Vladimir updated mem_cgroup_get_limit().
>
I'll check it.

>>   - force swap-in at reducing swap.limit
>
> Why?
>
If full, swap.limit cannot be reduced even if there are available memory in a cgroup.
Another cgroup cannot make use of the swap resource while it's occupied by other cgroup.
The job scheduler should have a chance to fix the situation.

Thanks,
-Kame

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