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-rw-r--r--mm/memcontrol.c83
1 files changed, 46 insertions, 37 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0980bbf6438d..04250cbf46c6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1916,15 +1916,18 @@ mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
return SKIP;
}
+static DEFINE_SPINLOCK(memcg_oom_lock);
+
/*
* Check OOM-Killer is already running under our hierarchy.
* If someone is running, return false.
- * Has to be called with memcg_oom_lock
*/
-static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg)
+static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter, *failed = NULL;
+ spin_lock(&memcg_oom_lock);
+
for_each_mem_cgroup_tree(iter, memcg) {
if (iter->oom_lock) {
/*
@@ -1938,33 +1941,33 @@ static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg)
iter->oom_lock = true;
}
- if (!failed)
- return true;
-
- /*
- * OK, we failed to lock the whole subtree so we have to clean up
- * what we set up to the failing subtree
- */
- for_each_mem_cgroup_tree(iter, memcg) {
- if (iter == failed) {
- mem_cgroup_iter_break(memcg, iter);
- break;
+ if (failed) {
+ /*
+ * OK, we failed to lock the whole subtree so we have
+ * to clean up what we set up to the failing subtree
+ */
+ for_each_mem_cgroup_tree(iter, memcg) {
+ if (iter == failed) {
+ mem_cgroup_iter_break(memcg, iter);
+ break;
+ }
+ iter->oom_lock = false;
}
- iter->oom_lock = false;
}
- return false;
+
+ spin_unlock(&memcg_oom_lock);
+
+ return !failed;
}
-/*
- * Has to be called with memcg_oom_lock
- */
-static int mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
+static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter;
+ spin_lock(&memcg_oom_lock);
for_each_mem_cgroup_tree(iter, memcg)
iter->oom_lock = false;
- return 0;
+ spin_unlock(&memcg_oom_lock);
}
static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
@@ -1988,7 +1991,6 @@ static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
atomic_add_unless(&iter->under_oom, -1, 0);
}
-static DEFINE_SPINLOCK(memcg_oom_lock);
static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
struct oom_wait_info {
@@ -2035,45 +2037,52 @@ static bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask,
int order)
{
struct oom_wait_info owait;
- bool locked, need_to_kill;
+ bool locked;
owait.memcg = memcg;
owait.wait.flags = 0;
owait.wait.func = memcg_oom_wake_function;
owait.wait.private = current;
INIT_LIST_HEAD(&owait.wait.task_list);
- need_to_kill = true;
- mem_cgroup_mark_under_oom(memcg);
- /* At first, try to OOM lock hierarchy under memcg.*/
- spin_lock(&memcg_oom_lock);
- locked = mem_cgroup_oom_lock(memcg);
/*
+ * As with any blocking lock, a contender needs to start
+ * listening for wakeups before attempting the trylock,
+ * otherwise it can miss the wakeup from the unlock and sleep
+ * indefinitely. This is just open-coded because our locking
+ * is so particular to memcg hierarchies.
+ *
* 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.
*/
prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
- if (!locked || memcg->oom_kill_disable)
- need_to_kill = false;
+ mem_cgroup_mark_under_oom(memcg);
+
+ locked = mem_cgroup_oom_trylock(memcg);
+
if (locked)
mem_cgroup_oom_notify(memcg);
- spin_unlock(&memcg_oom_lock);
- if (need_to_kill) {
+ if (locked && !memcg->oom_kill_disable) {
+ mem_cgroup_unmark_under_oom(memcg);
finish_wait(&memcg_oom_waitq, &owait.wait);
mem_cgroup_out_of_memory(memcg, mask, order);
} else {
schedule();
+ mem_cgroup_unmark_under_oom(memcg);
finish_wait(&memcg_oom_waitq, &owait.wait);
}
- spin_lock(&memcg_oom_lock);
- if (locked)
- mem_cgroup_oom_unlock(memcg);
- memcg_wakeup_oom(memcg);
- spin_unlock(&memcg_oom_lock);
- mem_cgroup_unmark_under_oom(memcg);
+ if (locked) {
+ mem_cgroup_oom_unlock(memcg);
+ /*
+ * There is no guarantee that an OOM-lock contender
+ * sees the wakeups triggered by the OOM kill
+ * uncharges. Wake any sleepers explicitely.
+ */
+ memcg_oom_recover(memcg);
+ }
if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
return false;