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 59927fb984de1703c67bc640c3e522d8b5276c73
("memcg: free mem_cgroup by RCU to fix oops").
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
mm/memcontrol.c | 51 +++++----------------------------------------------
1 file changed, 5 insertions(+), 46 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 348126a..eb27b58 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -267,28 +267,10 @@ struct mem_cgroup {
/* 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.
@@ -6143,29 +6125,6 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
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.
*/
@@ -6316,7 +6275,7 @@ static void mem_cgroup_css_free(struct cgroup *cont)
mem_cgroup_sockets_destroy(memcg);
- call_rcu(&memcg->rcu_freeing, free_rcu);
+ __mem_cgroup_free(memcg);
}
#ifdef CONFIG_MMU
--
1.8.0.2
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