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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 9 Apr 2018 10:03:03 -0700
Message-ID: <CA+55aFw1MoQ=7=U6QCGXAAiCniMKy8_igxgc8sMLykSRcDk-0g@mail.gmail.com>
Subject: Re: [bisected] 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 oopses on s390
To:     Sebastian Ott <sebott@linux.ibm.com>
Cc:     Kees Cook <keescook@chromium.org>,
        Sebastian Ott <sebott@linux.vnet.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Martin Uecker <Martin.Uecker@med.uni-goettingen.de>,
        Ingo Molnar <mingo@kernel.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
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On Mon, Apr 9, 2018 at 9:18 AM, Sebastian Ott <sebott@linux.ibm.com> wrote:
>
> Both of the following return 0 on my machine:
> +       pr_warn("%u\n", min_not_zero(100, 1000));
> +       pr_warn("%u\n", min_not_zero(1000, 100));

Oooh.

[ Raises hand, and says "I know, I know, pick me, pick me" ]

min_not_zero() hasinternal variables "__x" and "__y".

And "__cmp_once()" has internal variables "__x" and "__y".

When min_not_zero does

    min(__x, __y));

that expands to crazy stuff.

Out old "min()" had the internal variables called "min1" and "min2",
which is crazy too.

             Linus