lkml.org 
[lkml]   [2012]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 06/11] memcg: kmem controller infrastructure
On 08/15/2012 05:09 PM, Michal Hocko wrote:
> On Wed 15-08-12 13:42:24, Glauber Costa wrote:
> [...]
>>>> +
>>>> + ret = 0;
>>>> +
>>>> + if (!memcg)
>>>> + return ret;
>>>> +
>>>> + _memcg = memcg;
>>>> + ret = __mem_cgroup_try_charge(NULL, gfp, delta / PAGE_SIZE,
>>>> + &_memcg, may_oom);
>>>
>>> This is really dangerous because atomic allocation which seem to be
>>> possible could result in deadlocks because of the reclaim.
>>
>> Can you elaborate on how this would happen?
>
> Say you have an atomic allocation and we hit the limit so we get either
> to reclaim which can sleep or to oom which can sleep as well (depending
> on the oom_control).
>

I see now, you seem to be right.

How about we change the following code in mem_cgroup_do_charge:

if (gfp_mask & __GFP_NORETRY)
return CHARGE_NOMEM;

to:

if ((gfp_mask & __GFP_NORETRY) || (gfp_mask & __GFP_ATOMIC))
return CHARGE_NOMEM;

?

Would this take care of the issue ?


\
 
 \ /
  Last update: 2012-08-15 16:43    [W:0.147 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site