Michal Hocko wrote: > On Fri 19-02-16 22:51:38, Tetsuo Handa wrote: > > Currently, mem_cgroup_out_of_memory() is calling > > oom_scan_process_thread(&oc, task, totalpages) which includes > > a call to oom_unkillable_task(task, NULL, NULL) and then is > > calling oom_badness(task, memcg, NULL, totalpages) which includes > > a call to oom_unkillable_task(task, memcg, NULL). > > > > Since for_each_mem_cgroup_tree() iterates on only tasks from the given > > memcg hierarchy, there is no point with passing non-NULL memcg argument > > to oom_unkillable_task() via oom_badness(). > > > > Replace memcg argument with NULL in order to save a call to > > task_in_mem_cgroup(task, memcg) in oom_unkillable_task() > > which is always true. > > yes this is true but oom_badness is called from super slow path here so > I am not sure this change will buy anything. It makes the code little > bit more confusing because now you have to think twice (or git blame) to > see why the memcg == NULL is really OK. > > So I do not think this is an improvement. If anything wouldn't it be > cleaner to remove memcg parameter from oom_badness altogether and > instead do the task_in_mem_cgroup check where it is really needed? > In other words do the check in oom_kill_process when evaluating children > to sacrifice them? This patch is a clarification before proposing http://lkml.kernel.org/r/1455892411-7611-1-git-send-email-penguin-kernel@xxxxxxxxxxxxxxxxxxx which converts two oom_unkillable_task() calls into one and fixes infinite loop which will occur after we merge the OOM reaper. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>