Re: [PATCH v2 04/29] slub: always get the cache from its page inkfree

[Glauber Costa]

On 05/11/2012 03:17 PM, Christoph Lameter wrote:
> On Fri, 11 May 2012, Glauber Costa wrote:
>
> > On 05/11/2012 03:06 PM, Christoph Lameter wrote:
> > > On Fri, 11 May 2012, Glauber Costa wrote:
> > >
> > > > > Adding a VM_BUG_ON may be useful to make sure that kmem_cache_free is
> > > > > always passed the correct slab cache.
> > > >
> > > > Well, problem is , it isn't always passed the "correct" slab cache.
> > > > At least not after this series, since we'll have child caches associated
> > > > with
> > > > the main cache.
> > > >
> > > > So we'll pass, for instance, kmem_cache_free(dentry_cache...), but will in
> > > > fact free from the memcg copy of the dentry cache.
> > >
> > > Urg. But then please only do this for the MEMCG case and add a fat big
> > > warning in kmem_cache_free.
> >
> > I can do that, of course.
> > Another option if you don't oppose, is to add another field in the kmem_cache
> > structure (I tried to keep them at a minimum),
> > to record the parent cache we got created from.
> >
> > Then, it gets trivial to do the following:
> >
> > VM_BUG_ON(page->slab != s&&  page->slab != s->parent_cache);
>
> Sounds ok but I need to catch up on what this whole memcg thing in slab
> allocators should accomplish in order to say something definite.
Fair enough.

Thank you in advance for your time reviewing this!
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