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-rw-r--r--mm/oom_kill.c133
1 files changed, 80 insertions, 53 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 38f89ac2df7f..8ee92fb76968 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -596,7 +596,7 @@ static int oom_reaper(void *unused)
return 0;
}
-static void wake_oom_reaper(struct task_struct *tsk)
+void wake_oom_reaper(struct task_struct *tsk)
{
if (!oom_reaper_th)
return;
@@ -614,46 +614,6 @@ static void wake_oom_reaper(struct task_struct *tsk)
wake_up(&oom_reaper_wait);
}
-/* Check if we can reap the given task. This has to be called with stable
- * tsk->mm
- */
-void try_oom_reaper(struct task_struct *tsk)
-{
- struct mm_struct *mm = tsk->mm;
- struct task_struct *p;
-
- if (!mm)
- return;
-
- /*
- * There might be other threads/processes which are either not
- * dying or even not killable.
- */
- if (atomic_read(&mm->mm_users) > 1) {
- rcu_read_lock();
- for_each_process(p) {
- if (!process_shares_mm(p, mm))
- continue;
- if (fatal_signal_pending(p))
- continue;
-
- /*
- * If the task is exiting make sure the whole thread group
- * is exiting and cannot acces mm anymore.
- */
- if (signal_group_exit(p->signal))
- continue;
-
- /* Give up */
- rcu_read_unlock();
- return;
- }
- rcu_read_unlock();
- }
-
- wake_oom_reaper(tsk);
-}
-
static int __init oom_init(void)
{
oom_reaper_th = kthread_run(oom_reaper, NULL, "oom_reaper");
@@ -665,10 +625,6 @@ static int __init oom_init(void)
return 0;
}
subsys_initcall(oom_init)
-#else
-static void wake_oom_reaper(struct task_struct *tsk)
-{
-}
#endif
/**
@@ -745,6 +701,81 @@ void oom_killer_enable(void)
oom_killer_disabled = false;
}
+static inline bool __task_will_free_mem(struct task_struct *task)
+{
+ struct signal_struct *sig = task->signal;
+
+ /*
+ * A coredumping process may sleep for an extended period in exit_mm(),
+ * so the oom killer cannot assume that the process will promptly exit
+ * and release memory.
+ */
+ if (sig->flags & SIGNAL_GROUP_COREDUMP)
+ return false;
+
+ if (sig->flags & SIGNAL_GROUP_EXIT)
+ return true;
+
+ if (thread_group_empty(task) && (task->flags & PF_EXITING))
+ return true;
+
+ return false;
+}
+
+/*
+ * Checks whether the given task is dying or exiting and likely to
+ * release its address space. This means that all threads and processes
+ * sharing the same mm have to be killed or exiting.
+ */
+bool task_will_free_mem(struct task_struct *task)
+{
+ struct mm_struct *mm;
+ struct task_struct *p;
+ bool ret;
+
+ if (!__task_will_free_mem(task))
+ return false;
+
+ /*
+ * If the process has passed exit_mm we have to skip it because
+ * we have lost a link to other tasks sharing this mm, we do not
+ * have anything to reap and the task might then get stuck waiting
+ * for parent as zombie and we do not want it to hold TIF_MEMDIE
+ */
+ p = find_lock_task_mm(task);
+ if (!p)
+ return false;
+
+ mm = p->mm;
+ if (atomic_read(&mm->mm_users) <= 1) {
+ task_unlock(p);
+ return true;
+ }
+
+ /* pin the mm to not get freed and reused */
+ atomic_inc(&mm->mm_count);
+ task_unlock(p);
+
+ /*
+ * This is really pessimistic but we do not have any reliable way
+ * to check that external processes share with our mm
+ */
+ rcu_read_lock();
+ for_each_process(p) {
+ if (!process_shares_mm(p, mm))
+ continue;
+ if (same_thread_group(task, p))
+ continue;
+ ret = __task_will_free_mem(p);
+ if (!ret)
+ break;
+ }
+ rcu_read_unlock();
+ mmdrop(mm);
+
+ return ret;
+}
+
/*
* Must be called while holding a reference to p, which will be released upon
* returning.
@@ -766,15 +797,12 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
* If the task is already exiting, don't alarm the sysadmin or kill
* its children or threads, just set TIF_MEMDIE so it can die quickly
*/
- task_lock(p);
- if (p->mm && task_will_free_mem(p)) {
+ if (task_will_free_mem(p)) {
mark_oom_victim(p);
- try_oom_reaper(p);
- task_unlock(p);
+ wake_oom_reaper(p);
put_task_struct(p);
return;
}
- task_unlock(p);
if (__ratelimit(&oom_rs))
dump_header(oc, p);
@@ -944,10 +972,9 @@ bool out_of_memory(struct oom_control *oc)
* But don't select if current has already released its mm and cleared
* TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
*/
- if (current->mm &&
- (fatal_signal_pending(current) || task_will_free_mem(current))) {
+ if (current->mm && task_will_free_mem(current)) {
mark_oom_victim(current);
- try_oom_reaper(current);
+ wake_oom_reaper(current);
return true;
}