If OOM killer finds a task which is about to exit or is already doing so,
there is no need to kill anyone. It should just wait until task dies.

Add missing fatal_signal_pending() check and allow selected task to use memory
reserves in order to exit quickly.

Also remove redundant PF_EXITING check after victim has been selected.

Signed-off-by: Sergey Dyasly <dse...@gmail.com>
---
 mm/oom_kill.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 98e75f2..ef83b81 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -275,13 +275,16 @@ enum oom_scan_t oom_scan_process_thread(struct 
task_struct *task,
        if (oom_task_origin(task))
                return OOM_SCAN_SELECT;
 
-       if (task->flags & PF_EXITING && !force_kill) {
+       if ((task->flags & PF_EXITING || fatal_signal_pending(task)) &&
+           !force_kill) {
                /*
                 * If this task is not being ptraced on exit, then wait for it
                 * to finish before killing some other task unnecessarily.
                 */
-               if (!(task->group_leader->ptrace & PT_TRACE_EXIT))
+               if (!(task->group_leader->ptrace & PT_TRACE_EXIT)) {
+                       set_tsk_thread_flag(task, TIF_MEMDIE);
                        return OOM_SCAN_ABORT;
+               }
        }
        return OOM_SCAN_OK;
 }
@@ -412,16 +415,6 @@ void oom_kill_process(struct task_struct *p, gfp_t 
gfp_mask, int order,
        static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
                                              DEFAULT_RATELIMIT_BURST);
 
-       /*
-        * 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
-        */
-       if (p->flags & PF_EXITING) {
-               set_tsk_thread_flag(p, TIF_MEMDIE);
-               put_task_struct(p);
-               return;
-       }
-
        if (__ratelimit(&oom_rs))
                dump_header(p, gfp_mask, order, memcg, nodemask);
 
-- 
1.8.1.2

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