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Date:   Wed, 4 Jan 2023 13:07:35 +0100
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Peter Zijlstra <peterz@infradead.org>, corbet@lwn.net,
        will@kernel.org, boqun.feng@gmail.com, mark.rutland@arm.com,
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        cl@linux.com, gor@linux.ibm.com, agordeev@linux.ibm.com,
        borntraeger@linux.ibm.com, svens@linux.ibm.com,
        Herbert Xu <herbert@gondor.apana.org.au>, davem@davemloft.net,
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Subject: Re: [RFC][PATCH 11/12] slub: Replace cmpxchg_double()
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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.