diff options
| -rw-r--r-- | mm/memcontrol.c | 40 |
1 files changed, 12 insertions, 28 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3cd4f1e0bfb..3734fd6d113 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1447,32 +1447,6 @@ int mem_cgroup_swappiness(struct mem_cgroup *memcg) } /* - * memcg->moving_account is used for checking possibility that some thread is - * calling move_account(). When a thread on CPU-A starts moving pages under - * a memcg, other threads should check memcg->moving_account under - * rcu_read_lock(), like this: - * - * CPU-A CPU-B - * rcu_read_lock() - * memcg->moving_account+1 if (memcg->mocing_account) - * take heavy locks. - * synchronize_rcu() update something. - * rcu_read_unlock() - * start move here. - */ - -static void mem_cgroup_start_move(struct mem_cgroup *memcg) -{ - atomic_inc(&memcg->moving_account); - synchronize_rcu(); -} - -static void mem_cgroup_end_move(struct mem_cgroup *memcg) -{ - atomic_dec(&memcg->moving_account); -} - -/* * A routine for checking "mem" is under move_account() or not. * * Checking a cgroup is mc.from or mc.to or under hierarchy of @@ -5431,7 +5405,8 @@ static void mem_cgroup_clear_mc(void) mc.from = NULL; mc.to = NULL; spin_unlock(&mc.lock); - mem_cgroup_end_move(from); + + atomic_dec(&from->moving_account); } static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, @@ -5464,7 +5439,16 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, VM_BUG_ON(mc.precharge); VM_BUG_ON(mc.moved_charge); VM_BUG_ON(mc.moved_swap); - mem_cgroup_start_move(from); + + /* + * Signal mem_cgroup_begin_page_stat() to take + * the memcg's move_lock while we're moving + * its pages to another memcg. Then wait for + * already started RCU-only updates to finish. + */ + atomic_inc(&from->moving_account); + synchronize_rcu(); + spin_lock(&mc.lock); mc.from = from; mc.to = memcg; |