Re: [PATCH 1/2] gfp: add __GFP_NOACCOUNT

[Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>]

On Wed, May 06, 2015 at 01:59:41PM +0200, Michal Hocko wrote:
> On Tue 05-05-15 12:45:42, Vladimir Davydov wrote:
> > Not all kmem allocations should be accounted to memcg. The following
> > patch gives an example when accounting of a certain type of allocations
> > to memcg can effectively result in a memory leak.
> 
> > This patch adds the __GFP_NOACCOUNT flag which if passed to kmalloc
> > and friends will force the allocation to go through the root
> > cgroup. It will be used by the next patch.
> 
> The name of the flag is way too generic. It is not clear that the
> accounting is KMEMCG related.

The memory controller is the (primary) component that accounts
physical memory allocations in the kernel, so I don't see how this
would be ambiguous in any way.

> __GFP_NO_KMEMCG sounds better?

I think that's much worse.  I would prefer communicating the desired
behavior directly instead of having to derive it from a subsystem
name.

(And KMEMCG should not even be a term, it's all just the memory
controller, i.e. memcg.)