Re: [patch] mm: reduce pagetable-freeing latencies

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> The onstack array seems fine to me, even if you do end up deciding on
> an array of one.  Is there any evidence that it's a problem getting a
> page for the freeing (other than in circumstances that are already
> badly slowed down)?  It's obvious that we need a fallback route,
> but optimizing throughput on that route seems premature.

Hrm, no evidence of that so far indeed. I'm worried by the stack usage
of the unmap_mapping_ranges() but appart from that, no.

Appart from that, yeah, I suppose we can have a macro defining how many
on-stack backup we have and adjust it if we see that being a problem.
I'm not fan of dynamic on-stack allocations.

Ben.