[Devel] Re: [PATCH 12/23] slab: pass memcg parameter to kmem_cache_create

[Suleiman Souhlal]

On Sun, Apr 22, 2012 at 4:53 PM, Glauber Costa <glommer at parallels.com> wrote:
> Allow a memcg parameter to be passed during cache creation.
>
> Default function is created as a wrapper, passing NULL
> to the memcg version. We only merge caches that belong
> to the same memcg.
>
> This code was mostly written by Suleiman Souhlal and
> only adapted to my patchset, plus a couple of simplifications
>
> 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>
> ---
>  mm/slab.c |   38 +++++++++++++++++++++++++++++---------
>  1 files changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index a0d51dd..362bb6e 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2287,14 +2287,15 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
>  * cacheline.  This can be beneficial if you're counting cycles as closely
>  * as davem.
>  */
> -struct kmem_cache *
> -kmem_cache_create (const char *name, size_t size, size_t align,
> -       unsigned long flags, void (*ctor)(void *))
> +static struct kmem_cache *
> +__kmem_cache_create(struct mem_cgroup *memcg, const char *name, size_t size,
> +                   size_t align, unsigned long flags, void (*ctor)(void *))
>  {
> -       size_t left_over, slab_size, ralign;
> +       size_t left_over, orig_align, ralign, slab_size;
>        struct kmem_cache *cachep = NULL, *pc;
>        gfp_t gfp;
>
> +       orig_align = align;
>        /*
>         * Sanity checks... these are all serious usage bugs.
>         */
> @@ -2311,7 +2312,6 @@ kmem_cache_create (const char *name, size_t size, size_t align,
>         */
>        if (slab_is_available()) {
>                get_online_cpus();
> -               mutex_lock(&cache_chain_mutex);
>        }
>
>        list_for_each_entry(pc, &cache_chain, next) {
> @@ -2331,9 +2331,9 @@ kmem_cache_create (const char *name, size_t size, size_t align,
>                        continue;
>                }
>
> -               if (!strcmp(pc->name, name)) {
> +               if (!strcmp(pc->name, name) && !memcg) {
>                        printk(KERN_ERR
> -                              "kmem_cache_create: duplicate cache %s\n", name);
> +                       "kmem_cache_create: duplicate cache %s\n", name);
>                        dump_stack();
>                        goto oops;
>                }
> @@ -2434,6 +2434,9 @@ kmem_cache_create (const char *name, size_t size, size_t align,
>        cachep->nodelists = (struct kmem_list3 **)&cachep->array[nr_cpu_ids];
>
>        set_obj_size(cachep, size);
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +       cachep->memcg_params.orig_align = orig_align;
> +#endif
>  #if DEBUG
>
>        /*
> @@ -2541,7 +2544,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
>                BUG_ON(ZERO_OR_NULL_PTR(cachep->slabp_cache));
>        }
>        cachep->ctor = ctor;
> -       cachep->name = name;
> +       cachep->name = (char *)name;
> +
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +       mem_cgroup_register_cache(memcg, cachep);
> +       atomic_set(&cachep->memcg_params.refcnt, 1);
> +#endif

cache_cache probably doesn't get its id registered correctly. :-(
We might need to add a mem_cgroup_register_cache() call to kmem_cache_init().

-- Suleiman