Re: [PATCH v3 4/5] powerpc/mm: restore top-down allocation when using movable_node

[Reza Arbab]

On Tue, Oct 04, 2016 at 11:48:30AM +1100, Balbir Singh wrote:
> On 27/09/16 10:14, Reza Arbab wrote:
> > Right. To be clear, the background info I put in the commit log 
> > refers to x86, where the SRAT can describe movable nodes which exist 
> > at boot.  They're trying to avoid allocations from those nodes before 
> > they've been identified.
> >
> > On power, movable nodes can only exist via hotplug, so that scenario 
> > can't happen. We can immediately go back to top-down allocation. That 
> > is the missing call being added in the patch.
>
> Can we fix cmdline_parse_movable_node() to do the right thing? I 
> suspect that code is heavily x86 only in the sense that no other arch 
> needs it.

Good idea. We could change it so things only go bottom-up on x86 in the 
first place.

A nice consequence is that CONFIG_MOVABLE_NODE would then basically be 
usable on any platform with memory hotplug, not just PPC64 and X86_64.

I'll see if I can move the relevant code into an arch_*() call or 
otherwise factor it out.

--
Reza Arbab