[Devel] Re: [PATCH 17/23] kmem controller charge/uncharge infrastructure

[David Rientjes]

On Tue, 24 Apr 2012, Glauber Costa wrote:

> I think memcg is not necessarily wrong. That is because threads in a process
> share an address space, and you will eventually need to map a page to deliver
> it to userspace. The mm struct points you to the owner of that.
> 
> But that is not necessarily true for things that live in the kernel address
> space.
> 
> Do you view this differently ?
> 

Yes, for user memory, I see charging to p->mm->owner as allowing that 
process to eventually move and be charged to a different memcg and there's 
no way to do proper accounting if the charge is split amongst different 
memcgs because of thread membership to a set of memcgs.  This is 
consistent with charges for shared memory being moved when a thread 
mapping it moves to a new memcg, as well.