On Wed 13-01-16 21:11:30, Tetsuo Handa wrote: [...] > Those who use panic_on_oom = 1 expect that the system triggers kernel panic > rather than stall forever. This is a translation of administrator's wish that > "Please press SysRq-c on behalf of me if the memory exhausted. In that way, > I don't need to stand by in front of the console twenty-four seven." > > Those who use panic_on_oom = 0 expect that the OOM killer solves OOM condition > rather than stall forever. This is a translation of administrator's wish that > "Please press SysRq-f on behalf of me if the memory exhausted. In that way, > I don't need to stand by in front of the console twenty-four seven." I think you are missing an important point. There is _no reliable_ way to resolve the OOM condition in general except to panic the system. Even killing all user space tasks might not be sufficient in general because they might be blocked by an unkillable context (e.g. kernel thread). So if you need a reliable behavior then either use panic_on_oom=1 or provide a measure to panic after fixed timeout if the OOM cannot get resolved. We have seen patches in that regards but there was no general interest in them to merge them. All we can do is a best effort approach which tries to be optimized to reduce the impact of an unexpected SIGKILL sent to a "random" task. And this is a reasonable objective IMHO. This works well in 99% of cases. You can argue you do care about that 1% and I sympathy with you but steps to mitigate those shouldn't involve steps which bring another level of non-determinism into an already complicated system. This was the biggest issue of the early OOM killer. -- 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>