[Devel] Re: [PATCH 06/10] sl[au]b: Allocate objects from memcg cache

[Kirill A. Shutemov]

On Wed, Jul 25, 2012 at 06:38:17PM +0400, Glauber Costa wrote:
> We are able to match a cache allocation to a particular memcg.  If the
> task doesn't change groups during the allocation itself - a rare event,
> this will give us a good picture about who is the first group to touch a
> cache page.
> 
> This patch uses the now available infrastructure by calling
> memcg_kmem_get_cache() before all the cache allocations.
> 
> Signed-off-by: Glauber Costa <glommer at parallels.com>
> CC: Christoph Lameter <cl at linux.com>
> CC: Pekka Enberg <penberg at cs.helsinki.fi>
> CC: Michal Hocko <mhocko at suse.cz>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> CC: Johannes Weiner <hannes at cmpxchg.org>
> CC: Suleiman Souhlal <suleiman at google.com>
> ---
>  include/linux/slub_def.h |   18 +++++++++++++-----
>  mm/memcontrol.c          |    2 ++
>  mm/slab.c                |    4 ++++
>  mm/slub.c                |    1 +
>  4 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
> index 8bb8ad2..148000a 100644
> --- a/include/linux/slub_def.h
> +++ b/include/linux/slub_def.h
> @@ -13,6 +13,8 @@
>  #include <linux/kobject.h>
>  
>  #include <linux/kmemleak.h>
> +#include <linux/memcontrol.h>
> +#include <linux/mm.h>
>  
>  enum stat_item {
>  	ALLOC_FASTPATH,		/* Allocation from cpu slab */
> @@ -209,14 +211,14 @@ static __always_inline int kmalloc_index(size_t size)
>   * This ought to end up with a global pointer to the right cache
>   * in kmalloc_caches.
>   */
> -static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
> +static __always_inline struct kmem_cache *kmalloc_slab(gfp_t flags, size_t size)
>  {
>  	int index = kmalloc_index(size);
>  
>  	if (index == 0)
>  		return NULL;
>  
> -	return kmalloc_caches[index];
> +	return memcg_kmem_get_cache(kmalloc_caches[index], flags);
>  }
>  
>  void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
> @@ -225,7 +227,13 @@ void *__kmalloc(size_t size, gfp_t flags);
>  static __always_inline void *
>  kmalloc_order(size_t size, gfp_t flags, unsigned int order)
>  {
> -	void *ret = (void *) __get_free_pages(flags | __GFP_COMP, order);
> +	void *ret;
> +
> +	flags = __GFP_COMP;
> +#ifdef CONFIG_MEMCG_KMEM
> +	flags |= __GFP_KMEMCG;
> +#endif

Em.. I don't see where __GFP_KMEMCG is defined.
It should be 0 for !CONFIG_MEMCG_KMEM.

-- 
 Kirill A. Shutemov