Re: [PATCH] mm: memcontrol: Let mem_cgroup_move_account() have effect only if MMU enabled

[Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>]

On Wed 04-03-15 12:40:56, Johannes Weiner wrote:
> On Tue, Mar 03, 2015 at 02:45:24PM +0100, Michal Hocko wrote:
> > On Tue 03-03-15 06:42:01, Chen Gang wrote:
> > > When !MMU, it will report warning. The related warning with allmodconfig
> > > under c6x:
> > 
> > Does it even make any sense to enable CONFIG_MEMCG when !CONFIG_MMU?
> > Is anybody using this configuration and is it actually usable? My
> > knowledge about CONFIG_MMU is close to zero so I might be missing
> > something but I do not see a point into fixing compile warnings when
> > the whole subsystem is not usable in the first place.
> 
> It's very limited, and anonymous memory is not even charged right now,
> even though it could be -- see nommu.c::do_mmap_private().  But there
> is nothing inherent in the memcg functionality that would require an
> MMU I guess, except for these ridiculous charge moving pte walkers.
> 
> > > Signed-off-by: Chen Gang <gang.chen.5i5j-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> 
> Acked-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>

Thanks, I will post the patch to Andrew.

-- 
Michal Hocko
SUSE Labs