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From:   Andy Lutomirski <luto@kernel.org>
Date:   Wed, 18 Dec 2019 18:48:24 -0800
Message-ID: <CALCETrWJ8PLbxvX6yuP7Q3kz_=dZinacUd-3-OqUkZNSMCE34g@mail.gmail.com>
Subject: Re: [PATCH v2 0/4] x86: fix get_nr_restart_syscall()
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Oleg Nesterov <oleg@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
        Jan Kratochvil <jan.kratochvil@redhat.com>,
        Pedro Alves <palves@redhat.com>, Peter Anvin <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>
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On Wed, Dec 18, 2019 at 12:02 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, Dec 18, 2019 at 7:19 AM Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > Andy, Linus, do you have any objections?
>
> It's ok by me, no objections. I still don't love your "hide the bit in
> thread flags over return to user space", and would still prefer it in
> the restart block, but I don't care _that_ deeply.
>

I'd rather stick it in restart_block.  I'd also like to see the kernel
*verify* that the variant of restart_syscall() that's invoked is the
same as the variant that should be invoked.  In my mind, very few
syscalls say "I can't believe there are no major bugs in here" like
restart_syscall(), and being conservative is nice.