diff options
| -rw-r--r-- | mm/memcontrol.c | 70 |
1 files changed, 30 insertions, 40 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index eba04a481e03..cfd2db08cfe1 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -89,7 +89,6 @@ enum mem_cgroup_stat_index { MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */ MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */ MEM_CGROUP_STAT_DATA, /* end of data requires synchronization */ - MEM_CGROUP_ON_MOVE, /* someone is moving account between groups */ MEM_CGROUP_STAT_NSTATS, }; @@ -298,6 +297,10 @@ struct mem_cgroup { */ unsigned long move_charge_at_immigrate; /* + * set > 0 if pages under this cgroup are moving to other cgroup. + */ + atomic_t moving_account; + /* * percpu counter. */ struct mem_cgroup_stat_cpu *stat; @@ -1287,35 +1290,36 @@ int mem_cgroup_swappiness(struct mem_cgroup *memcg) return memcg->swappiness; } +/* + * 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) { - int cpu; - - get_online_cpus(); - spin_lock(&memcg->pcp_counter_lock); - for_each_online_cpu(cpu) - per_cpu(memcg->stat->count[MEM_CGROUP_ON_MOVE], cpu) += 1; - memcg->nocpu_base.count[MEM_CGROUP_ON_MOVE] += 1; - spin_unlock(&memcg->pcp_counter_lock); - put_online_cpus(); - + atomic_inc(&memcg->moving_account); synchronize_rcu(); } static void mem_cgroup_end_move(struct mem_cgroup *memcg) { - int cpu; - - if (!memcg) - return; - get_online_cpus(); - spin_lock(&memcg->pcp_counter_lock); - for_each_online_cpu(cpu) - per_cpu(memcg->stat->count[MEM_CGROUP_ON_MOVE], cpu) -= 1; - memcg->nocpu_base.count[MEM_CGROUP_ON_MOVE] -= 1; - spin_unlock(&memcg->pcp_counter_lock); - put_online_cpus(); + /* + * Now, mem_cgroup_clear_mc() may call this function with NULL. + * We check NULL in callee rather than caller. + */ + if (memcg) + atomic_dec(&memcg->moving_account); } + /* * 2 routines for checking "mem" is under move_account() or not. * @@ -1331,7 +1335,7 @@ static void mem_cgroup_end_move(struct mem_cgroup *memcg) static bool mem_cgroup_stealed(struct mem_cgroup *memcg) { VM_BUG_ON(!rcu_read_lock_held()); - return this_cpu_read(memcg->stat->count[MEM_CGROUP_ON_MOVE]) > 0; + return atomic_read(&memcg->moving_account) > 0; } static bool mem_cgroup_under_move(struct mem_cgroup *memcg) @@ -1882,8 +1886,8 @@ bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask, int order) * by flags. * * Considering "move", this is an only case we see a race. To make the race - * small, we check MEM_CGROUP_ON_MOVE percpu value and detect there are - * possibility of race condition. If there is, we take a lock. + * small, we check mm->moving_account and detect there are possibility of race + * If there is, we take a lock. */ void mem_cgroup_update_page_stat(struct page *page, @@ -2100,17 +2104,6 @@ static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu) per_cpu(memcg->stat->events[i], cpu) = 0; memcg->nocpu_base.events[i] += x; } - /* need to clear ON_MOVE value, works as a kind of lock. */ - per_cpu(memcg->stat->count[MEM_CGROUP_ON_MOVE], cpu) = 0; - spin_unlock(&memcg->pcp_counter_lock); -} - -static void synchronize_mem_cgroup_on_move(struct mem_cgroup *memcg, int cpu) -{ - int idx = MEM_CGROUP_ON_MOVE; - - spin_lock(&memcg->pcp_counter_lock); - per_cpu(memcg->stat->count[idx], cpu) = memcg->nocpu_base.count[idx]; spin_unlock(&memcg->pcp_counter_lock); } @@ -2122,11 +2115,8 @@ static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb, struct memcg_stock_pcp *stock; struct mem_cgroup *iter; - if ((action == CPU_ONLINE)) { - for_each_mem_cgroup(iter) - synchronize_mem_cgroup_on_move(iter, cpu); + if (action == CPU_ONLINE) return NOTIFY_OK; - } if ((action != CPU_DEAD) || action != CPU_DEAD_FROZEN) return NOTIFY_OK; |