Re: revamp vmem_altmap / dev_pagemap handling V3

Michal Hocko
2018-01-08T21:45:52Z

On Mon 08-01-18 13:27:13, Dan Williams wrote:
> On Mon, Jan 8, 2018 at 12:25 PM, Michal Hocko <mhocko@kernel.org> wrote:
> > On Mon 08-01-18 11:44:02, Dan Williams wrote:
> >> On Mon, Jan 8, 2018 at 3:26 AM, Christoph Hellwig <hch@lst.de> wrote:
> >> > Any chance to get this fully reviewed and picked up before the
> >> > end of the merge window?
> >>
> >> I'm fine carrying these through the nvdimm tree, but I'd need an ack
> >> from the mm folks for all the code touches related to arch_add_memory.
> >
> > I am sorry to be slow here but I am out of time right now - yeah having
> > a lot of fun kaiser time. I didn't get to look at these patches at all
> > yet but the changelog suggests that you want to remove vmem_altmap.
> > I've had plans to (ab)use this for self hosted struct pages for memory
> > hotplug http://lkml.kernel.org/r/20170801124111.28881-1-mhocko@kernel.org
> > That work is stalled though because it is buggy and I was too busy to
> > finish that work. Anyway, if you believe that removing vmem_altmap is a
> > good step in general I will find another way. I wasn't really happy how
> > the whole thing is grafted to the memory hotplug and (ab)used it only
> > because it was handy and ready for reuse.
>
> You misread, these are keeping vmem_altmap and cleaning up the usage
> to pass the vmem_altmap pointer through all paths rather than the
> tricky radix lookup we were doing previously.

Good to hear. I really didn't get further than reading through email
subjects and for some reason I misread those.

> > Anyway if you need a review of mm parts from me, you will have to wait
> > some more. If this requires some priority then go ahead and merge
> > it. Times are just too crazy right now.
>
> Since you were planning on reusing vmem_altmap I think these patches
> make your job easier. I don't see the risk in merging these, we've
> squeezed out a few bugs and all the nvdimm unit tests are passing.

Good, then really do not wait for me if this aims to get merged soon.

> > Sorry about that.
>
> No worries, quite a few of us are in that same boat.

Yeah the boat is quite large I suspect...

--
Michal Hocko
SUSE Labs