memcg: remove pcp_counter_lock

Commit 733a572e66d2 ("memcg: make mem_cgroup_read_{stat|event}() iterate
possible cpus instead of online") removed the last use of the per memcg
pcp_counter_lock but forgot to remove the variable.

Kill the vestigial variable.

Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 0 insertions, 2 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index ad800e62cb7a..6452ff4c463f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -242,7 +242,6 @@ struct mem_cgroup {
          * percpu counter.
          */
         struct mem_cgroup_stat_cpu __percpu *stat;
-        spinlock_t pcp_counter_lock;
 
 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
         struct cg_proto tcp_mem;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 03cc0a742ff1..1fedbde68f59 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4185,7 +4185,6 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
         if (memcg_wb_domain_init(memcg, GFP_KERNEL))
                 goto out_free_stat;
 
-        spin_lock_init(&memcg->pcp_counter_lock);
         return memcg;
 
 out_free_stat: