linux-kernel - Re: [patch 0/3] x86/pti: Fix various fallout

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Message-Id: <BBE59049-4750-4415-B353-FC2AFF38C482@amacapital.net>
Date:   Sat, 30 Dec 2017 18:23:24 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        Dominik Brodowski <linux@...inikbrodowski.net>
Subject: Re: [patch 0/3] x86/pti: Fix various fallout



> On Dec 30, 2017, at 2:06 PM, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> 
>> On Sat, Dec 30, 2017 at 1:35 PM, Ingo Molnar <mingo@...nel.org> wrote:
>> 
>> Linus, I suspect -rc6 is imminent, and it would be nice to at least have the LDT
>> error path fix in. I'll send you these fixes tomorrow, but feel free to pick it up
>> from email if you wanted to release -rc6 today.
> 
> I'll do rc6 tomorrow probably around this time (early afternoon PST).
> So I think I should be ok just waiting for your pull request.

FWIW, I think this big is at worst just a memory leak.  Once an mm has any LDT mapped, mapping a second one can't fail because the entire LDT area is under 512 pages, meaning that nothing needs to be allocated, so there's no opportunity for failure.

So it's an embarrassing bug, but not catastrophic.

> 
> Thanks,
> 
>                  Linus