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Date:   Mon, 9 Jan 2023 17:28:32 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Heiko Carstens <hca@linux.ibm.com>, corbet@lwn.net,
        will@kernel.org, boqun.feng@gmail.com, mark.rutland@arm.com,
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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:

> But I *do* note that this patch seems to be the only one that depends
> on the new this_cpu_cmpxchg() updates to make it just automatically do
> 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?

I ran into a ton of casting trouble when compiling kernel/fork.c which
uses this_cpu_cmpxchg() on a pointer type and the compiler hates casting
pointers to an integer that is not the exact same size.