memcg: don't need to free memcg via RCU or workqueue
Now memcg has the same life cycle with its corresponding cgroup, and a
cgroup is freed via RCU and then mem_cgroup_css_free() will be called in
a work function, so we can simply call __mem_cgroup_free() in
mem_cgroup_css_free().
This actually reverts commit 59927fb984d ("memcg: free mem_cgroup by RCU
to fix oops").
Signed-off-by: Li Zefan <lizefan@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Glauber Costa <glommer@openvz.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fa521a2..d12ca6f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -263,28 +263,10 @@
/* vmpressure notifications */
struct vmpressure vmpressure;
- union {
- /*
- * the counter to account for mem+swap usage.
- */
- struct res_counter memsw;
-
- /*
- * rcu_freeing is used only when freeing struct mem_cgroup,
- * so put it into a union to avoid wasting more memory.
- * It must be disjoint from the css field. It could be
- * in a union with the res field, but res plays a much
- * larger part in mem_cgroup life than memsw, and might
- * be of interest, even at time of free, when debugging.
- * So share rcu_head with the less interesting memsw.
- */
- struct rcu_head rcu_freeing;
- /*
- * We also need some space for a worker in deferred freeing.
- * By the time we call it, rcu_freeing is no longer in use.
- */
- struct work_struct work_freeing;
- };
+ /*
+ * the counter to account for mem+swap usage.
+ */
+ struct res_counter memsw;
/*
* the counter to account for kernel memory usage.
@@ -6211,29 +6193,6 @@
vfree(memcg);
}
-
-/*
- * Helpers for freeing a kmalloc()ed/vzalloc()ed mem_cgroup by RCU,
- * but in process context. The work_freeing structure is overlaid
- * on the rcu_freeing structure, which itself is overlaid on memsw.
- */
-static void free_work(struct work_struct *work)
-{
- struct mem_cgroup *memcg;
-
- memcg = container_of(work, struct mem_cgroup, work_freeing);
- __mem_cgroup_free(memcg);
-}
-
-static void free_rcu(struct rcu_head *rcu_head)
-{
- struct mem_cgroup *memcg;
-
- memcg = container_of(rcu_head, struct mem_cgroup, rcu_freeing);
- INIT_WORK(&memcg->work_freeing, free_work);
- schedule_work(&memcg->work_freeing);
-}
-
/*
* Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
*/
@@ -6383,7 +6342,7 @@
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
memcg_destroy_kmem(memcg);
- call_rcu(&memcg->rcu_freeing, free_rcu);
+ __mem_cgroup_free(memcg);
}
#ifdef CONFIG_MMU