oom: thaw the OOM victim if it is frozen
oom_kill_process only sets TIF_MEMDIE flag and sends a signal to the
victim. This is basically noop when the task is frozen though because the
task sleeps in the uninterruptible sleep. The victim is eventually thawed
later when oom_scan_process_thread meets the task again in a later OOM
invocation so the OOM killer doesn't live lock. But this is less than
optimal.
Let's add __thaw_task into mark_tsk_oom_victim after we set TIF_MEMDIE to
the victim. We are not checking whether the task is frozen because that
would be racy and __thaw_task does that already. oom_scan_process_thread
doesn't need to care about freezer anymore as TIF_MEMDIE and freezer are
excluded completely now.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 80b34e2..3cbd76b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -266,8 +266,6 @@
* Don't allow any other task to have access to the reserves.
*/
if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
- if (unlikely(frozen(task)))
- __thaw_task(task);
if (!force_kill)
return OOM_SCAN_ABORT;
}
@@ -423,6 +421,14 @@
void mark_tsk_oom_victim(struct task_struct *tsk)
{
set_tsk_thread_flag(tsk, TIF_MEMDIE);
+
+ /*
+ * Make sure that the task is woken up from uninterruptible sleep
+ * if it is frozen because OOM killer wouldn't be able to free
+ * any memory and livelock. freezing_slow_path will tell the freezer
+ * that TIF_MEMDIE tasks should be ignored.
+ */
+ __thaw_task(tsk);
}
/**
