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 <[email protected]> --- mm/oom_kill.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 80b34e285f96..3cbd76b8c13b 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -266,8 +266,6 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task, * 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 note_oom_kill(void) 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); } /** -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
