Re: [RFC] asm-generic/tlb: stub out pmd_free_tlb() if __PAGETABLE_PMD_FOLDED

From: Matthew Wilcox
Date: Mon Oct 14 2019 - 17:48:08 EST

On Mon, Oct 14, 2019 at 01:38:34PM -0700, Linus Torvalds wrote:
> And now I've said pgd/pud/p4d/pmd so many times that I've confused
> myself and think I'm wrong again, and I think that historically -
> originally - we always had a pgd, and then the pmd didn't exist
> because it was folded into it. That makes sense from a x86 naming
> standpoint. Then x86 _did_ get a pmd, and then we added more levels in
> between, and other architectures did things differently.

Oh my goodness. Thank you for writing all this out and finally getting
to this point. I was reading the whole thing thinking "This is different
from what I remember" and then you got here. This explains so much about
how our MM does/doesn't work, and it's not just me that's confused ;-)