Re: [GIT PULL] MM updates for 6.6-rc1

[Matthew Wilcox]

On Tue, Aug 29, 2023 at 02:31:38PM -0700, Linus Torvalds wrote:
> On Mon, 28 Aug 2023 at 18:43, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > csky tree, arch/csky/abiv2/cacheflush.c:
> > https://lkml.kernel.org/r/20230815104604.54f65293@xxxxxxxxxxxxxxxx
> 
> At least this resolution in linux-next was wrong. It would just keep
> on doing a cache invalidate on the same one-page address range over
> and over again.
> 
> I think I did it right, but obviously can't test (and am too lazy to
> build-test too).
> 
> Of course, it won't actually matter unless you have large folio on
> csky, which is probably hard to impossible to trigger in practice, but
> I thought I'd mention it if for no other reason than Guo Ren to be
> aware and at least test-build and maybe think about it.

As far as I can tell, csky doesn't enable support for HUGETLBFS nor for
TRANSPARENT_HUGEPAGE and large folios are currently disabled unless you
have TRANSPARENT_HUGEPAGE, simply because they rely on infrastructure
that's only built for TRANSPARENT_HUGEPAGE.  We should probably fix that
at some point; allocating in larger chunks is beneficial even if you don't
have PMD sized TLB entries.  But the motivation to do that work has been
lacking; there are plenty of more important projects in the queue.