Re: [PATCH v2 06/13] slab: Add kmem_cache_gfp_flags() helper function.

[Glauber Costa]

On 03/14/2012 03:21 AM, Suleiman Souhlal wrote:
> On Sun, Mar 11, 2012 at 3:53 AM, Glauber Costa<glommer@xxxxxxxxxxxxx>  wrote:
> > On 03/10/2012 12:39 AM, Suleiman Souhlal wrote:
> > > This function returns the gfp flags that are always applied to
> > > allocations of a kmem_cache.
> > >
> > > Signed-off-by: Suleiman Souhlal<suleiman@xxxxxxxxxx>
> > > ---
> > >   include/linux/slab_def.h |    6 ++++++
> > >   include/linux/slob_def.h |    6 ++++++
> > >   include/linux/slub_def.h |    6 ++++++
> > >   3 files changed, 18 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
> > > index fbd1117..25f9a6a 100644
> > > --- a/include/linux/slab_def.h
> > > +++ b/include/linux/slab_def.h
> > > @@ -159,6 +159,12 @@ found:
> > >         return __kmalloc(size, flags);
> > >   }
> > >
> > > +static inline gfp_t
> > > +kmem_cache_gfp_flags(struct kmem_cache *cachep)
> > > +{
> > > +       return cachep->gfpflags;
> > > +}
> > > +
> > >   #ifdef CONFIG_NUMA
> > >   extern void *__kmalloc_node(size_t size, gfp_t flags, int node);
> > >   extern void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int
> > > node);
> > > diff --git a/include/linux/slob_def.h b/include/linux/slob_def.h
> > > index 0ec00b3..3fa527d 100644
> > > --- a/include/linux/slob_def.h
> > > +++ b/include/linux/slob_def.h
> > > @@ -34,4 +34,10 @@ static __always_inline void *__kmalloc(size_t size,
> > > gfp_t flags)
> > >         return kmalloc(size, flags);
> > >   }
> > >
> > > +static inline gfp_t
> > > +kmem_cache_gfp_flags(struct kmem_cache *cachep)
> > > +{
> > > +       return 0;
> > > +}
> > > +
> > >   #endif /* __LINUX_SLOB_DEF_H */
> > > diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
> > > index a32bcfd..5911d81 100644
> > > --- a/include/linux/slub_def.h
> > > +++ b/include/linux/slub_def.h
> > > @@ -313,4 +313,10 @@ static __always_inline void *kmalloc_node(size_t
> > > size, gfp_t flags, int node)
> > >   }
> > >   #endif
> > >
> > > +static inline gfp_t
> > > +kmem_cache_gfp_flags(struct kmem_cache *cachep)
> > > +{
> > > +       return cachep->allocflags;
> > > +}
> > > +
> >
> >
> > Why is this needed? Can't the caller just call
> > mem_cgroup_get_kmem_cache(cachep, flags | cachep->allocflags) ?
>
> Because slub calls this cachep->allocflags, while slab calls it
> cachep->gfpflags.

So what?
That function is only called from slab.c anyway. Let slab call it
mem_cgroup_get_kmem_cache(cachep, flags | cachep->allocflags);
and slub
mem_cgroup_get_kmem_cache(cachep, flags | cachep->gfpflags);
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