On 09/19, Michal Hocko wrote: > > On Sat 19-09-15 17:03:16, Oleg Nesterov wrote: > > > > Stupid idea. Can't we help the memory hog to free its memory? This is > > orthogonal to other improvements we can do. > > > > Please don't tell me the patch below is ugly, incomplete and suboptimal > > in many ways, I know ;) I am not sure it is even correct. Just to explain > > what I mean. > > Unmapping the memory for the oom victim has been already mentioned as a > way to improve the OOM killer behavior. Nobody has implemented that yet > though unfortunately. I have that on my TODO list since we have > discussed it with Mel at LSF. OK, good. So perhaps we should try to do this. > > > Perhaps oom_unmap_func() should only zap the anonymous vmas... and there > > are a lot of other details which should be discussed if this can make any > > sense. > > I have just returned from an internal conference so my head is > completely cabbaged. I will have a look on Monday. From a quick look > the idea is feasible. You cannot rely on the worker context because > workqueues might be completely stuck with at this stage. Yes this is true. See another email, probably oom-kill.c needs its own kthread. And again, we should actually try to avoid queue_work or queue_kthread_work in any case. But not in the initial implementation. And initial implementation could use workqueues, I think. I the likely case system_unbound_wq pool should have an idle thread. > You also cannot > do take mmap_sem directly because that might be held already so you need > a try_lock instead. Still can't understand this part. See other emails, perhaps I missed something. > Focusing on anonymous vmas first sounds like a good > idea to me because that would be simpler I guess. And safer. Oleg. -- 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>