linux-kernel - Re: memcg oops: memcg_kmem_charge_memcg()->try_charge()->page_counter_try

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Message-ID: <1540846014.4434.10.camel@gmx.de>
Date:   Mon, 29 Oct 2018 21:46:54 +0100
From:   Mike Galbraith <efault@....de>
To:     Roman Gushchin <guro@...com>
Cc:     Michal Hocko <mhocko@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>
Subject: Re: memcg oops:
 memcg_kmem_charge_memcg()->try_charge()->page_counter_try_charge()->BOOM

On Mon, 2018-10-29 at 18:54 +0000, Roman Gushchin wrote:
> 
> Hi Mike!
> 
> Thank you for the report!
> 
> Do you see it reliable every time you boot up the machine?

Yeah.

> How do you run kvm?

My VMs are full SW/data clones of my i7-4790/openSUSE <release> box.

>  Is there something special about your cgroup setup?

No, I generally have no use for cgroups.

> I've made several attempts to reproduce the issue, but haven't got anything
> so far. I've used your config, and played with different cgroups setups.

Ah, I have cgroup_disable=memory on the command line, which turns out
to be why your box doesn't explode, while mine does.

> Do you know where in the page_counter_try_charge() it fails?
> 
> Also, can you, please, check if the following patch mitigates the problem?

Yeah, that plugs it up.

	-Mike