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From: Arnd Bergmann <arnd@arndb.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>, X86 ML <x86@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
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        <linux-arm-kernel@lists.infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>
Subject: Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR
Date: Tue, 03 Jan 2017 23:07:20 +0100
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On Tuesday, January 3, 2017 10:29:33 AM CET Andy Lutomirski wrote:
> 
> Hmm.  What if we approached this a bit differently?  We could add a
> single new personality bit ADDR_LIMIT_EXPLICIT.  Setting this bit
> cause PER_LINUX32_3GB etc to be automatically cleared.

Both the ADDR_LIMIT_32BIT and ADDR_LIMIT_3GB flags I guess?

> When
> ADDR_LIMIT_EXPLICIT is in effect, prctl can set a 64-bit numeric
> limit.  If ADDR_LIMIT_EXPLICIT is cleared, the prctl value stops being
> settable and reading it via prctl returns whatever is implied by the
> other personality bits.

I don't see anything wrong with it, but I'm a bit confused now
what this would be good for, compared to using just prctl.

Is this about setuid clearing the personality but not the prctl,
or something else?

	Arnd