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    SubjectRe: [PATCH 2/8] memcg, slab: remove cgroup name from memcg cache names
    On Sun 02-02-14 20:33:47, Vladimir Davydov wrote:
    > The cgroup name is not informative at all in case the cgroup hierarchy
    > is not flat. Besides, we can always find the memcg a particular cache
    > belongs to by its kmemcg id, which is now exported via "memory.kmem.id"
    > cgroup fs file for each memcg.
    >
    > So let's remove the cgroup name part from kmem caches names - it will
    > greatly simplify the call paths and make the code look clearer.
    >
    > Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>

    I guess this one doesn't make much sense withou 1/8, right?

    > ---
    > mm/memcontrol.c | 63 +++++++++++++-----------------------------------------
    > mm/slab_common.c | 6 +++++-
    > 2 files changed, 20 insertions(+), 49 deletions(-)
    >
    > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
    > index 91d242707404..3351c5b5486d 100644
    > --- a/mm/memcontrol.c
    > +++ b/mm/memcontrol.c
    > @@ -3405,44 +3405,6 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
    > schedule_work(&cachep->memcg_params->destroy);
    > }
    >
    > -static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
    > - struct kmem_cache *s)
    > -{
    > - struct kmem_cache *new = NULL;
    > - static char *tmp_name = NULL;
    > - static DEFINE_MUTEX(mutex); /* protects tmp_name */
    > -
    > - BUG_ON(!memcg_can_account_kmem(memcg));
    > -
    > - mutex_lock(&mutex);
    > - /*
    > - * kmem_cache_create_memcg duplicates the given name and
    > - * cgroup_name for this name requires RCU context.
    > - * This static temporary buffer is used to prevent from
    > - * pointless shortliving allocation.
    > - */
    > - if (!tmp_name) {
    > - tmp_name = kmalloc(PATH_MAX, GFP_KERNEL);
    > - if (!tmp_name)
    > - goto out;
    > - }
    > -
    > - rcu_read_lock();
    > - snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name,
    > - memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup));
    > - rcu_read_unlock();
    > -
    > - new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align,
    > - (s->flags & ~SLAB_PANIC), s->ctor, s);
    > - if (new)
    > - new->allocflags |= __GFP_KMEMCG;
    > - else
    > - new = s;
    > -out:
    > - mutex_unlock(&mutex);
    > - return new;
    > -}
    > -
    > void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
    > {
    > struct kmem_cache *c;
    > @@ -3489,12 +3451,6 @@ void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
    > mutex_unlock(&activate_kmem_mutex);
    > }
    >
    > -struct create_work {
    > - struct mem_cgroup *memcg;
    > - struct kmem_cache *cachep;
    > - struct work_struct work;
    > -};
    > -
    > static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
    > {
    > struct kmem_cache *cachep;
    > @@ -3512,13 +3468,24 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
    > mutex_unlock(&memcg->slab_caches_mutex);
    > }
    >
    > +struct create_work {
    > + struct mem_cgroup *memcg;
    > + struct kmem_cache *cachep;
    > + struct work_struct work;
    > +};
    > +
    > static void memcg_create_cache_work_func(struct work_struct *w)
    > {
    > - struct create_work *cw;
    > + struct create_work *cw = container_of(w, struct create_work, work);
    > + struct mem_cgroup *memcg = cw->memcg;
    > + struct kmem_cache *s = cw->cachep;
    > + struct kmem_cache *new;
    >
    > - cw = container_of(w, struct create_work, work);
    > - memcg_create_kmem_cache(cw->memcg, cw->cachep);
    > - css_put(&cw->memcg->css);
    > + new = kmem_cache_create_memcg(memcg, s->name, s->object_size, s->align,
    > + (s->flags & ~SLAB_PANIC), s->ctor, s);
    > + if (new)
    > + new->allocflags |= __GFP_KMEMCG;
    > + css_put(&memcg->css);
    > kfree(cw);
    > }
    >
    > diff --git a/mm/slab_common.c b/mm/slab_common.c
    > index 1ec3c619ba04..152d9b118b7a 100644
    > --- a/mm/slab_common.c
    > +++ b/mm/slab_common.c
    > @@ -213,7 +213,11 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
    > s->align = calculate_alignment(flags, align, size);
    > s->ctor = ctor;
    >
    > - s->name = kstrdup(name, GFP_KERNEL);
    > + if (!memcg)
    > + s->name = kstrdup(name, GFP_KERNEL);
    > + else
    > + s->name = kasprintf(GFP_KERNEL, "%s:%d",
    > + name, memcg_cache_id(memcg));
    > if (!s->name)
    > goto out_free_cache;
    >
    > --
    > 1.7.10.4
    >

    --
    Michal Hocko
    SUSE Labs


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