On Tue 08-01-19 23:21:23, Tetsuo Handa wrote: > From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > > If memcg OOM events in different domains are pending, already OOM-killed > threads needlessly wait for pending memcg OOM events in different domains. > An out_of_memory() call is slow because it involves printk(). With slow > serial consoles, out_of_memory() might take more than a second. Therefore, > allowing killed processes to quickly call mmput() from exit_mm() from > do_exit() will help calling __mmput() (which can reclaim more memory than > the OOM reaper can reclaim) quickly. Can you post it separately out of this thread please? It is really a separate topic and I do not want to end with back and forth without making a further progress. > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > --- > mm/memcontrol.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 90eb2e2..a7d3ba9 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1389,14 +1389,19 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, > }; > bool ret = true; > > - mutex_lock(&oom_lock); > - > /* > - * multi-threaded tasks might race with oom_reaper and gain > - * MMF_OOM_SKIP before reaching out_of_memory which can lead > - * to out_of_memory failure if the task is the last one in > - * memcg which would be a false possitive failure reported > + * Multi-threaded tasks might race with oom_reaper() and gain > + * MMF_OOM_SKIP before reaching out_of_memory(). But if current > + * thread was already killed or is ready to terminate, there is > + * no need to call out_of_memory() nor wait for oom_reaoer() to > + * set MMF_OOM_SKIP. These three checks minimize possibility of > + * needlessly calling out_of_memory() and try to call exit_mm() > + * as soon as possible. > */ > + if (mutex_lock_killable(&oom_lock)) > + return true; > + if (fatal_signal_pending(current)) > + goto unlock; > if (tsk_is_oom_victim(current)) > goto unlock; > > -- > 1.8.3.1 > -- Michal Hocko SUSE Labs
