On Wed 04-10-17 12:33:14, Shakeel Butt wrote: > > > > I am not objecting to the patch I would just like to understand the > > runaway case. ep_insert seems to limit the maximum number of watches to > > max_user_watches which should be ~4% of lowmem if I am following the > > code properly. pwq_cache should be bound by the number of watches as > > well, or am I misunderstanding the code? > > > > You are absolutely right that there is a per-user limit (~4% of total > memory if no highmem) on these caches. I think it is too generous > particularly in the scenario where jobs of multiple users are running > on the system and the administrator is reducing cost by overcomitting > the memory. This is unaccounted kernel memory and will not be > considered by the oom-killer. I think by accounting it to kmemcg, for > systems with kmem accounting enabled, we can provide better isolation > between jobs of different users. Thanks for the clarification. For some reason I didn't figure that the limit is per user, even though the name suggests so. -- Michal Hocko SUSE Labs
