linux-kernel - Re: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init

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Message-ID: <e8149c9e-10f8-aa74-ff0e-e2de923b2128@linux.intel.com>
Date:   Wed, 1 Nov 2017 14:52:48 -0700
From:   Dave Hansen <dave.hansen@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        moritz.lipp@...k.tugraz.at,
        Daniel Gruss <daniel.gruss@...k.tugraz.at>,
        michael.schwarz@...k.tugraz.at,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...gle.com>,
        Hugh Dickins <hughd@...gle.com>, X86 ML <x86@...nel.org>
Subject: Re: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init_mm page
 tables

On 11/01/2017 02:28 PM, Thomas Gleixner wrote:
> On Wed, 1 Nov 2017, Andy Lutomirski wrote:
>> The vsyscall page is _PAGE_USER and lives in init_mm via the fixmap.
> 
> Groan, forgot about that abomination, but still there is no point in having
> it marked PAGE_USER in the init_mm at all, kaiser or not.

So shouldn't this patch effectively make the vsyscall page unusable?
Any idea why that didn't show up in any of the x86 selftests?