Hi Andrew! Can you, please, pull this patch? Thank you! Roman On Fri, Jun 02, 2017 at 10:13:38AM +0200, Michal Hocko wrote: > On Thu 01-06-17 19:41:13, Roman Gushchin wrote: > > On Wed, May 31, 2017 at 06:39:29PM +0200, Michal Hocko wrote: > > > On Tue 30-05-17 19:52:31, Roman Gushchin wrote: > > > > >From c57e3674efc609f8364f5e228a2c1309cfe99901 Mon Sep 17 00:00:00 2001 > > > > From: Roman Gushchin <guro@xxxxxx> > > > > Date: Tue, 23 May 2017 17:37:55 +0100 > > > > Subject: [PATCH v2] mm,oom: add tracepoints for oom reaper-related events > > > > > > > > During the debugging of the problem described in > > > > https://lkml.org/lkml/2017/5/17/542 and fixed by Tetsuo Handa > > > > in https://lkml.org/lkml/2017/5/19/383 , I've found that > > > > the existing debug output is not really useful to understand > > > > issues related to the oom reaper. > > > > > > > > So, I assume, that adding some tracepoints might help with > > > > debugging of similar issues. > > > > > > > > Trace the following events: > > > > 1) a process is marked as an oom victim, > > > > 2) a process is added to the oom reaper list, > > > > 3) the oom reaper starts reaping process's mm, > > > > 4) the oom reaper finished reaping, > > > > 5) the oom reaper skips reaping. > > > > > > > > How it works in practice? Below is an example which show > > > > how the problem mentioned above can be found: one process is added > > > > twice to the oom_reaper list: > > > > > > > > $ cd /sys/kernel/debug/tracing > > > > $ echo "oom:mark_victim" > set_event > > > > $ echo "oom:wake_reaper" >> set_event > > > > $ echo "oom:skip_task_reaping" >> set_event > > > > $ echo "oom:start_task_reaping" >> set_event > > > > $ echo "oom:finish_task_reaping" >> set_event > > > > $ cat trace_pipe > > > > allocate-502 [001] .... 91.836405: mark_victim: pid=502 > > > > allocate-502 [001] .N.. 91.837356: wake_reaper: pid=502 > > > > allocate-502 [000] .N.. 91.871149: wake_reaper: pid=502 > > > > oom_reaper-23 [000] .... 91.871177: start_task_reaping: pid=502 > > > > oom_reaper-23 [000] .N.. 91.879511: finish_task_reaping: pid=502 > > > > oom_reaper-23 [000] .... 91.879580: skip_task_reaping: pid=502 > > > > > > OK, this is much better! The clue here would be that we got 2 > > > wakeups for the same task, right? > > > Do you think it would make sense to put more context to those > > > tracepoints? E.g. skip_task_reaping can be due to lock contention or the > > > mm gone. wake_reaper is similar. > > > > I agree, that some context might be useful under some circumstances, > > but I don't think we should add any additional fields until we will have some examples > > of where this data is actually useful. If we will need it, we can easily add it later. > > OK, fair enough. > > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > -- > 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>
