7:08 a.m.
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