Re: [PATCH v14 08/14] mm: multi-gen LRU: support page table walks

Peter Zijlstra
2022-10-20T18:56:40Z

On Thu, Oct 20, 2022 at 10:35:28AM -0700, Linus Torvalds wrote:
> On Thu, Oct 20, 2022 at 7:14 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > So I've been sitting on these here patches (and never having time to
> > repost them), which is how I noticed in the first place:
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=x86/mm.pae
>
> Well, that seems an improvement. I don't love how GUP_GET_PTE_LOW_HIGH
> now affects the PMD too, but if it's ok for all the three users, I
> guess it's ok. Maybe rename it now that it's not just the PTE?
>
> That said, I reacted to that cmpxchg loop:
>
> } while (cmpxchg64(&pmdp->pmd, old.pmd, 0ULL) != old.pmd);
>
> is this series just so old (but rebased) that it doesn't use "try_cmpxchg64()"?

Yep -- it's *that* old :-/ You're not in fact the first to point that
out.

I'll make time tomorrow to fix it up and respin and send out. This is as
good a time as any to get rid of carrying these patches myself.