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

[Suleiman Souhlal]

On Sun, Mar 11, 2012 at 3:53 AM, Glauber Costa <glommer at parallels.com> 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 at google.com>
>> ---
>>  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.

I'll look into renaming one of them to match the other.

-- Suleiman