From: Tejun Heo <tj@xxxxxxxxxx> Subject: slab: reorganize memcg_cache_params We're going to change how memcg caches are iterated. In preparation, clean up and reorganize memcg_cache_params. * The shared ->list is replaced by ->children in root and ->children_node in children. * ->is_root_cache is removed. Instead ->root_cache is moved out of the child union and now used by both root and children. NULL indicates root cache. Non-NULL a memcg one. This patch doesn't cause any observable behavior changes. Link: http://lkml.kernel.org/r/20170117235411.9408-5-tj@xxxxxxxxxx Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Acked-by: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/slab.h | 33 ++++++++++++++++++++++++--------- mm/slab.h | 6 +++--- mm/slab_common.c | 25 +++++++++++++------------ 3 files changed, 40 insertions(+), 24 deletions(-) diff -puN include/linux/slab.h~slab-reorganize-memcg_cache_params include/linux/slab.h --- a/include/linux/slab.h~slab-reorganize-memcg_cache_params +++ a/include/linux/slab.h @@ -545,22 +545,37 @@ struct memcg_cache_array { * array to be accessed without taking any locks, on relocation we free the old * version only after a grace period. * - * Child caches will hold extra metadata needed for its operation. Fields are: + * Root and child caches hold different metadata. * - * @memcg: pointer to the memcg this cache belongs to - * @root_cache: pointer to the global, root cache, this cache was derived from + * @root_cache: Common to root and child caches. NULL for root, pointer to + * the root cache for children. * - * Both root and child caches of the same kind are linked into a list chained - * through @list. + * The following fields are specific to root caches. + * + * @memcg_caches: kmemcg ID indexed table of child caches. This table is + * used to index child cachces during allocation and cleared + * early during shutdown. + * + * @children: List of all child caches. While the child caches are also + * reachable through @memcg_caches, a child cache remains on + * this list until it is actually destroyed. + * + * The following fields are specific to child caches. + * + * @memcg: Pointer to the memcg this cache belongs to. + * + * @children_node: List node for @root_cache->children list. */ struct memcg_cache_params { - bool is_root_cache; - struct list_head list; + struct kmem_cache *root_cache; union { - struct memcg_cache_array __rcu *memcg_caches; + struct { + struct memcg_cache_array __rcu *memcg_caches; + struct list_head children; + }; struct { struct mem_cgroup *memcg; - struct kmem_cache *root_cache; + struct list_head children_node; }; }; }; diff -puN mm/slab.h~slab-reorganize-memcg_cache_params mm/slab.h --- a/mm/slab.h~slab-reorganize-memcg_cache_params +++ a/mm/slab.h @@ -206,12 +206,12 @@ int __kmem_cache_alloc_bulk(struct kmem_ * slab_mutex. */ #define for_each_memcg_cache(iter, root) \ - list_for_each_entry(iter, &(root)->memcg_params.list, \ - memcg_params.list) + list_for_each_entry(iter, &(root)->memcg_params.children, \ + memcg_params.children_node) static inline bool is_root_cache(struct kmem_cache *s) { - return s->memcg_params.is_root_cache; + return !s->memcg_params.root_cache; } static inline bool slab_equal_or_root(struct kmem_cache *s, diff -puN mm/slab_common.c~slab-reorganize-memcg_cache_params mm/slab_common.c --- a/mm/slab_common.c~slab-reorganize-memcg_cache_params +++ a/mm/slab_common.c @@ -140,9 +140,9 @@ int __kmem_cache_alloc_bulk(struct kmem_ #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) void slab_init_memcg_params(struct kmem_cache *s) { - s->memcg_params.is_root_cache = true; - INIT_LIST_HEAD(&s->memcg_params.list); + s->memcg_params.root_cache = NULL; RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL); + INIT_LIST_HEAD(&s->memcg_params.children); } static int init_memcg_params(struct kmem_cache *s, @@ -150,10 +150,10 @@ static int init_memcg_params(struct kmem { struct memcg_cache_array *arr; - if (memcg) { - s->memcg_params.is_root_cache = false; - s->memcg_params.memcg = memcg; + if (root_cache) { s->memcg_params.root_cache = root_cache; + s->memcg_params.memcg = memcg; + INIT_LIST_HEAD(&s->memcg_params.children_node); return 0; } @@ -223,7 +223,7 @@ int memcg_update_all_caches(int num_memc static void unlink_memcg_cache(struct kmem_cache *s) { - list_del(&s->memcg_params.list); + list_del(&s->memcg_params.children_node); } #else static inline int init_memcg_params(struct kmem_cache *s, @@ -594,7 +594,8 @@ void memcg_create_kmem_cache(struct mem_ goto out_unlock; } - list_add(&s->memcg_params.list, &root_cache->memcg_params.list); + list_add(&s->memcg_params.children_node, + &root_cache->memcg_params.children); /* * Since readers won't lock (see cache_from_memcg_idx()), we need a @@ -690,7 +691,7 @@ static int shutdown_memcg_caches(struct * list so as not to try to destroy it for a second * time while iterating over inactive caches below. */ - list_move(&c->memcg_params.list, &busy); + list_move(&c->memcg_params.children_node, &busy); else /* * The cache is empty and will be destroyed soon. Clear @@ -705,17 +706,17 @@ static int shutdown_memcg_caches(struct * Second, shutdown all caches left from memory cgroups that are now * offline. */ - list_for_each_entry_safe(c, c2, &s->memcg_params.list, - memcg_params.list) + list_for_each_entry_safe(c, c2, &s->memcg_params.children, + memcg_params.children_node) shutdown_cache(c); - list_splice(&busy, &s->memcg_params.list); + list_splice(&busy, &s->memcg_params.children); /* * A cache being destroyed must be empty. In particular, this means * that all per memcg caches attached to it must be empty too. */ - if (!list_empty(&s->memcg_params.list)) + if (!list_empty(&s->memcg_params.children)) return -EBUSY; return 0; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
