On Sat 12-01-19 00:37:05, Tetsuo Handa wrote: > 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. I meant to use the same check consistently. If we can bypass the charge under a list of conditions in the charge path we should be surely be able to the the same for the oom path. I will not insist but unless there is a strong reason I would prefer that. > 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. No, this makes no sense what so ever. -- Michal Hocko SUSE Labs
