From 9a41707bd3a0811919000daf094e9d50ea65f7da Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Mon, 7 Apr 2014 15:39:31 -0700 Subject: slub: rework sysfs layout for memcg caches Currently, we try to arrange sysfs entries for memcg caches in the same manner as for global caches. Apart from turning /sys/kernel/slab into a mess when there are a lot of kmem-active memcgs created, it actually does not work properly - we won't create more than one link to a memcg cache in case its parent is merged with another cache. For instance, if A is a root cache merged with another root cache B, we will have the following sysfs setup: X A -> X B -> X where X is some unique id (see create_unique_id()). Now if memcgs M and N start to allocate from cache A (or B, which is the same), we will get: X X:M X:N A -> X B -> X A:M -> X:M A:N -> X:N Since B is an alias for A, we won't get entries B:M and B:N, which is confusing. It is more logical to have entries for memcg caches under the corresponding root cache's sysfs directory. This would allow us to keep sysfs layout clean, and avoid such inconsistencies like one described above. This patch does the trick. It creates a "cgroup" kset in each root cache kobject to keep its children caches there. Signed-off-by: Vladimir Davydov Cc: Michal Hocko Cc: Johannes Weiner Cc: David Rientjes Cc: Pekka Enberg Cc: Glauber Costa Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slub.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) (limited to 'mm/slub.c') diff --git a/mm/slub.c b/mm/slub.c index 33939e72bc37..3508edec19f9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5138,6 +5138,15 @@ static const struct kset_uevent_ops slab_uevent_ops = { static struct kset *slab_kset; +static inline struct kset *cache_kset(struct kmem_cache *s) +{ +#ifdef CONFIG_MEMCG_KMEM + if (!is_root_cache(s)) + return s->memcg_params->root_cache->memcg_kset; +#endif + return slab_kset; +} + #define ID_STR_LENGTH 64 /* Create a unique string id for a slab cache: @@ -5203,7 +5212,7 @@ static int sysfs_slab_add(struct kmem_cache *s) name = create_unique_id(s); } - s->kobj.kset = slab_kset; + s->kobj.kset = cache_kset(s); err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); if (err) { kobject_put(&s->kobj); @@ -5216,6 +5225,18 @@ static int sysfs_slab_add(struct kmem_cache *s) kobject_put(&s->kobj); return err; } + +#ifdef CONFIG_MEMCG_KMEM + if (is_root_cache(s)) { + s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj); + if (!s->memcg_kset) { + kobject_del(&s->kobj); + kobject_put(&s->kobj); + return -ENOMEM; + } + } +#endif + kobject_uevent(&s->kobj, KOBJ_ADD); if (!unmergeable) { /* Setup first alias */ @@ -5234,6 +5255,9 @@ static void sysfs_slab_remove(struct kmem_cache *s) */ return; +#ifdef CONFIG_MEMCG_KMEM + kset_unregister(s->memcg_kset); +#endif kobject_uevent(&s->kobj, KOBJ_REMOVE); kobject_del(&s->kobj); kobject_put(&s->kobj); -- cgit v1.2.3