Re: [RFC][PATCH 11/12] slub: Replace cmpxchg_double()

Heiko Carstens
2023-01-04T12:08:11Z

On Tue, Jan 03, 2023 at 11:08:29AM -0800, Linus Torvalds wrote:
> On Tue, Jan 3, 2023 at 9:17 AM Heiko Carstens <hca@linux.ibm.com> wrote:
> >
> > On Mon, Dec 19, 2022 at 04:35:36PM +0100, Peter Zijlstra wrote:
> > >
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > ---
> > > include/linux/slub_def.h | 12 ++-
> > > mm/slab.h | 41 +++++++++++--
> > > mm/slub.c | 146 ++++++++++++++++++++++++++++-------------------
> > > 3 files changed, 135 insertions(+), 64 deletions(-)
> >
> > Does this actually work? Just wondering since I end up with an instant
> > list corruption on s390. Might be endianness related, but I can't see
> > anything obvious at a first glance.
...
> the right thing for a 128-bit value. And I have to admit that all
> those games with __pcpu_cast_128() make no sense to me. Why isn't it
> just using "u128" everywhere without any odd _Generic() games?

That would have been my question as well, but the good thing is that
you pointed me to the percpu patch - Initially didn't expect any s390
specific code in there, but that is where the bug is.
I'll reply to that patch.