On 2019/01/11 22:34, Michal Hocko wrote: > On Fri 11-01-19 21:40:52, Tetsuo Handa wrote: > [...] >> Did you notice that there is no >> >> "Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n" >> >> line between >> >> [ 71.304703][ T9694] Memory cgroup out of memory: Kill process 9692 (a.out) score 904 or sacrifice child >> >> and >> >> [ 71.309149][ T54] oom_reaper: reaped process 9750 (a.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:185532kB >> >> ? Then, you will find that [ T9694] failed to reach for_each_process(p) loop inside >> __oom_kill_process() in the first round of out_of_memory() call because >> find_lock_task_mm() == NULL at __oom_kill_process() because Ctrl-C made that victim >> complete exit_mm() before find_lock_task_mm() is called. > > OK, so we haven't killed anything because the victim has exited by the > time we wanted to do so. We still have other tasks sharing that mm > pending and not killed because nothing has killed them yet, right? The OOM killer invoked by [ T9694] called printk() but didn't kill anything. Instead, SIGINT from Ctrl-C killed all thread groups sharing current->mm. > > How come the oom reaper could act on this oom event at all then? > > What am I missing? > The OOM killer invoked by [ T9750] did not call printk() but hit task_will_free_mem(current) in out_of_memory() and invoked the OOM reaper, without calling mark_oom_victim() on all thread groups sharing current->mm. Did you notice that I wrote that Since mm-oom-marks-all-killed-tasks-as-oom-victims.patch does not call mark_oom_victim() when task_will_free_mem() == true, ? :-(
