Re: API for setting multiple PTEs at once

Matthew Wilcox
2023-02-07T20:27:57Z

On Thu, Feb 02, 2023 at 09:14:23PM +0000, Matthew Wilcox wrote:
> For those of you not subscribed, linux-mm is currently discussing
> how best to handle page faults on large folios. I simply made it work
> when adding large folio support. Now Yin Fengwei is working on
> making it fast.

OK, here's an actual implementation:

https://lore.kernel.org/linux-mm/20230207194937.122543-3-willy@infradead.org/

It survives a run of xfstests. If your architecture doesn't store its
PFNs at PAGE_SHIFT, you're going to want to implement your own set_ptes(),
or you'll see entirely the wrong pages mapped into userspace. You may
also wish to implement set_ptes() if it can be done more efficiently
than __pte(pteval(pte) + PAGE_SIZE).

Architectures that implement things like flush_icache_page() and
update_mmu_cache() may want to propose batched versions of those.
That's alpha, csky, m68k, mips, nios2, parisc, sh,
arm, loongarch, openrisc, powerpc, riscv, sparc and xtensa.
Maintainers BCC'd, mailing lists CC'd.

I'm happy to collect implementations and submit them as part of a v6.