On Wed 17-02-16 14:31:54, David Rientjes wrote: > On Wed, 17 Feb 2016, Tetsuo Handa wrote: > > > oom_scan_process_thread() returns OOM_SCAN_SELECT when there is a > > thread which returns oom_task_origin() == true. But it is possible > > that such thread is marked as OOM-unkillable. In that case, the OOM > > killer must not select such process. > > > > Since it is meaningless to return OOM_SCAN_OK for OOM-unkillable > > process because subsequent oom_badness() call will return 0, this > > patch changes oom_scan_process_thread to return OOM_SCAN_CONTINUE > > if that process is marked as OOM-unkillable (regardless of > > oom_task_origin()). > > > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > > Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> > > --- > > mm/oom_kill.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > index 7653055..cf87153 100644 > > --- a/mm/oom_kill.c > > +++ b/mm/oom_kill.c > > @@ -282,7 +282,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, > > if (!is_sysrq_oom(oc)) > > return OOM_SCAN_ABORT; > > } > > - if (!task->mm) > > + if (!task->mm || task->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) > > return OOM_SCAN_CONTINUE; > > > > /* > > I'm getting multiple emails from you with the identical patch, something > is definitely wacky in your toolchain. > > Anyway, this is NACK'd since task->signal->oom_score_adj is checked under > task_lock() for threads with memory attached, that's the purpose of > finding the correct thread in oom_badness() and taking task_lock(). We > aren't going to duplicate logic in several functions that all do the same > thing. Is the task_lock really necessary, though? E.g. oom_task_origin() doesn't seem to depend on it for task->signal safety. If you are referring to races with changing oom_score_adj does such a race matter at all? To me this looks like a reasonable cleanup because we _know_ that OOM_SCORE_ADJ_MIN means OOM_SCAN_CONTINUE and do not really have to go down to oom_badness to find that out. Or what am I missing? -- Michal Hocko SUSE Labs -- 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>