On Fri 29-04-16 11:16:44, Vlastimil Babka wrote: > On 04/28/2016 02:35 PM, Michal Hocko wrote: [...] > >My main point was to simplify the code and get rid of as much compaction > >specific hacks as possible. We might very well drop this later on but it > >would be at least less code to grasp through. I do not have any problem > >with dropping this but I think this shouldn't collide with other patches > >much so reducing the number of lines is worth it. Good point, I have completely missed this part. > I just realized it also affects khugepaged, and not just THP page faults, so > it may potentially cripple THP's completely. My main issue is that the > reasons to bail out includes COMPACT_SKIPPED, and for a wrong reason (see > the comment above). It also goes against the comment below the noretry > label: > > * High-order allocations do not necessarily loop after direct reclaim > * and reclaim/compaction depends on compaction being called after > * reclaim so call directly if necessary. > > Given that THP's are large, I expect reclaim would indeed be quite often > necessary before compaction, and the first optimistic async compaction > attempt will just return SKIPPED. After this patch, there will be no more > reclaim/compaction attempts for THP's, including khugepaged. And given the > change of THP page fault defaults, even crippling that path should no longer > be necessary. > > So I would just drop this for now indeed. Agreed, thanks for catching this. Andrew, could you drop this patch please? It was supposed to be a mere clean up without any effect on the oom detection. Thanks! -- 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>