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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun, 20 Dec 2020 13:06:37 -0800
Message-ID: <CAHk-=wimOSd-41nDAYKfbUCNN=o22NOrGT6U38=KLqw5NBsZNg@mail.gmail.com>
Subject: Re: [PATCH] epoll: fix compat syscall wire up of epoll_pwait2
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Peter Anvin <hpa@zytor.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Arnd Bergmann <arnd@arndb.de>,
        Matthew Wilcox <willy@infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        "the arch/x86 maintainers" <x86@kernel.org>
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On Sun, Dec 20, 2020 at 12:14 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> The sigset_t argument is actually compatible between x86-32 and x86-64

Well, random high bits in size_t or the pointer value aren't. So it
still looks a bit iffy to me.

But it might end up working almost by accident.

          Linus