diff options
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 134 |
1 files changed, 107 insertions, 27 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f7b910fc14fb..7973b5221fb8 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -203,7 +203,7 @@ struct mem_cgroup { * Should the accounting and control be hierarchical, per subtree? */ bool use_hierarchy; - unsigned long last_oom_jiffies; + atomic_t oom_lock; atomic_t refcnt; unsigned int swappiness; @@ -1246,32 +1246,102 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem, return total; } -bool mem_cgroup_oom_called(struct task_struct *task) +static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data) { - bool ret = false; - struct mem_cgroup *mem; - struct mm_struct *mm; + int *val = (int *)data; + int x; + /* + * Logically, we can stop scanning immediately when we find + * a memcg is already locked. But condidering unlock ops and + * creation/removal of memcg, scan-all is simple operation. + */ + x = atomic_inc_return(&mem->oom_lock); + *val = max(x, *val); + return 0; +} +/* + * Check OOM-Killer is already running under our hierarchy. + * If someone is running, return false. + */ +static bool mem_cgroup_oom_lock(struct mem_cgroup *mem) +{ + int lock_count = 0; - rcu_read_lock(); - mm = task->mm; - if (!mm) - mm = &init_mm; - mem = mem_cgroup_from_task(rcu_dereference(mm->owner)); - if (mem && time_before(jiffies, mem->last_oom_jiffies + HZ/10)) - ret = true; - rcu_read_unlock(); - return ret; + mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb); + + if (lock_count == 1) + return true; + return false; } -static int record_last_oom_cb(struct mem_cgroup *mem, void *data) +static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data) { - mem->last_oom_jiffies = jiffies; + /* + * When a new child is created while the hierarchy is under oom, + * mem_cgroup_oom_lock() may not be called. We have to use + * atomic_add_unless() here. + */ + atomic_add_unless(&mem->oom_lock, -1, 0); return 0; } -static void record_last_oom(struct mem_cgroup *mem) +static void mem_cgroup_oom_unlock(struct mem_cgroup *mem) { - mem_cgroup_walk_tree(mem, NULL, record_last_oom_cb); + mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb); +} + +static DEFINE_MUTEX(memcg_oom_mutex); +static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq); + +/* + * try to call OOM killer. returns false if we should exit memory-reclaim loop. + */ +bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask) +{ + DEFINE_WAIT(wait); + bool locked; + + /* At first, try to OOM lock hierarchy under mem.*/ + mutex_lock(&memcg_oom_mutex); + locked = mem_cgroup_oom_lock(mem); + /* + * Even if signal_pending(), we can't quit charge() loop without + * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL + * under OOM is always welcomed, use TASK_KILLABLE here. + */ + if (!locked) + prepare_to_wait(&memcg_oom_waitq, &wait, TASK_KILLABLE); + mutex_unlock(&memcg_oom_mutex); + + if (locked) + mem_cgroup_out_of_memory(mem, mask); + else { + schedule(); + finish_wait(&memcg_oom_waitq, &wait); + } + mutex_lock(&memcg_oom_mutex); + mem_cgroup_oom_unlock(mem); + /* + * Here, we use global waitq .....more fine grained waitq ? + * Assume following hierarchy. + * A/ + * 01 + * 02 + * assume OOM happens both in A and 01 at the same time. Tthey are + * mutually exclusive by lock. (kill in 01 helps A.) + * When we use per memcg waitq, we have to wake up waiters on A and 02 + * in addtion to waiters on 01. We use global waitq for avoiding mess. + * It will not be a big problem. + * (And a task may be moved to other groups while it's waiting for OOM.) + */ + wake_up_all(&memcg_oom_waitq); + mutex_unlock(&memcg_oom_mutex); + + if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current)) + return false; + /* Give chance to dying process */ + schedule_timeout(1); + return true; } /* @@ -1443,11 +1513,14 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, struct res_counter *fail_res; int csize = CHARGE_SIZE; - if (unlikely(test_thread_flag(TIF_MEMDIE))) { - /* Don't account this! */ - *memcg = NULL; - return 0; - } + /* + * Unlike gloval-vm's OOM-kill, we're not in memory shortage + * in system level. So, allow to go ahead dying process in addition to + * MEMDIE process. + */ + if (unlikely(test_thread_flag(TIF_MEMDIE) + || fatal_signal_pending(current))) + goto bypass; /* * We always charge the cgroup the mm_struct belongs to. @@ -1560,11 +1633,15 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, } if (!nr_retries--) { - if (oom) { - mem_cgroup_out_of_memory(mem_over_limit, gfp_mask); - record_last_oom(mem_over_limit); + if (!oom) + goto nomem; + if (mem_cgroup_handle_oom(mem_over_limit, gfp_mask)) { + nr_retries = MEM_CGROUP_RECLAIM_RETRIES; + continue; } - goto nomem; + /* When we reach here, current task is dying .*/ + css_put(&mem->css); + goto bypass; } } if (csize > PAGE_SIZE) @@ -1574,6 +1651,9 @@ done: nomem: css_put(&mem->css); return -ENOMEM; +bypass: + *memcg = NULL; + return 0; } /* |