On 2019/01/12 0:07, Michal Hocko wrote: > On Fri 11-01-19 23:31:18, Tetsuo Handa wrote: >> 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. > > I still do not get it. Those other processes are not sharing signals. > Or is it due to injecting the signal too all of them with the proper > timing? Pressing Ctrl-C between after task_will_free_mem(p) in oom_kill_process() and before __oom_kill_process() (e.g. dump_header()) made fatal_signal_pending() = T for all of them. > Anyway, could you update your patch and abstract > if (unlikely(tsk_is_oom_victim(current) || > fatal_signal_pending(current) || > current->flags & PF_EXITING)) > > in try_charge and reuse it in mem_cgroup_out_of_memory under the > oom_lock with an explanation please? I don't think doing so makes sense, for tsk_is_oom_victim(current) = T && fatal_signal_pending(current) == F can't happen for mem_cgroup_out_of_memory() under the oom_lock, and current->flags cannot get PF_EXITING when current is inside mem_cgroup_out_of_memory(). fatal_signal_pending(current) alone is appropriate for mem_cgroup_out_of_memory() under the oom_lock because tsk_is_oom_victim(current) = F && fatal_signal_pending(current) == T can happen there. Also, doing so might become wrong in future, for mem_cgroup_out_of_memory() is also called from memory_max_write() which does not bail out upon PF_EXITING. I don't think we can call memory_max_write() after current thread got PF_EXITING, but nobody knows what change will happen in future.
