On Tue 09-02-21 17:17:22, David Hildenbrand wrote: > On 09.02.21 14:25, Michal Hocko wrote: > > On Tue 09-02-21 11:23:35, David Hildenbrand wrote: > > [...] > > > I am constantly trying to fight for making more stuff MOVABLE instead of > > > going into the other direction (e.g., because it's easier to implement, > > > which feels like the wrong direction). > > > > > > Maybe I am the only person that really cares about ZONE_MOVABLE these days > > > :) I can't stop such new stuff from popping up, so at least I want it to be > > > documented. > > > > MOVABLE zone is certainly an important thing to keep working. And there > > is still quite a lot of work on the way. But as I've said this is more > > of a outlier than a norm. On the other hand movable zone is kinda hard > > requirement for a lot of application and it is to be expected that > > many features will be less than 100% compatible. Some usecases even > > impossible. That's why I am arguing that we should have a central > > document where the movable zone is documented with all the potential > > problems we have encountered over time and explicitly state which > > features are fully/partially incompatible. > > > > I'll send a mail during the next weeks to gather current restrictions to > document them (and include my brain dump). We might see more excessive use > of ZONE_MOVABLE in the future and as history told us, of CMA as well. We > really should start documenting/caring. Excellent! Thanks a lot. I will do my best to help reviewing that. > @Mike, it would be sufficient for me if one of your patches at least mention > the situation in the description like > > "Please note that secretmem currently behaves much more like long-term GUP > instead of mlocked memory; secretmem is unmovable memory directly > consumed/controlled by user space. secretmem cannot be placed onto > ZONE_MOVABLE/CMA. Sounds good to me. -- Michal Hocko SUSE Labs
