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From: Andy Lutomirski <luto@kernel.org>
To: Rik van Riel <riel@surriel.com>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	Borislav Petkov <bp@alien8.de>, Jann Horn <jannh@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	stable <stable@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Nadav Amit <nadav.amit@gmail.com>
Subject: Re: [PATCH v2] x86/nmi: Fix some races in NMI uaccess
Date: Tue, 28 Aug 2018 20:46:35 -0700	[thread overview]
Message-ID: <CALCETrX2v_g_+TpX1DEZasHGi=8Y3w3ka=yYEaTxgFDnPy67nw@mail.gmail.com> (raw)
In-Reply-To: <20180828135647.6d516048@imladris.surriel.com>

On Tue, Aug 28, 2018 at 10:56 AM, Rik van Riel <riel@surriel.com> wrote:
> On Mon, 27 Aug 2018 16:04:16 -0700
> Andy Lutomirski <luto@kernel.org> wrote:
>
>> The 0day bot is still chewing on this, but I've tested it a bit locally
>> and it seems to do the right thing.
>
> Hi Andy,
>
> the version of the patch below should fix the bug we talked about
> in email yesterday.  It should automatically cover kernel threads
> in lazy TLB mode, because current->mm will be NULL, while the
> cpu_tlbstate.loaded_mm should never be NULL.
>

That's better than mine.  I tweaked it a bit and added some debugging,
and I got this:

https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/fixes&id=dd956eba16646fd0b15c3c0741269dfd84452dac

I made the loaded_mm handling a little more conservative to make it
more obvious that switch_mm_irqs_off() is safe regardless of exactly
when it gets called relative to switching current.

  reply	other threads:[~2018-08-29  3:47 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27 23:04 [PATCH] x86/nmi: Fix some races in NMI uaccess Andy Lutomirski
2018-08-27 23:12 ` Jann Horn
2018-08-27 23:25   ` Andy Lutomirski
2018-08-27 23:34     ` Jann Horn
2018-08-28  1:31 ` Rik van Riel
2018-08-28  2:10   ` Andy Lutomirski
2018-08-28 13:50     ` Rik van Riel
2018-08-28 17:56 ` [PATCH v2] " Rik van Riel
2018-08-29  3:46   ` Andy Lutomirski [this message]
2018-08-29 15:17     ` Rik van Riel
2018-08-29 15:36       ` Andy Lutomirski
2018-08-29 15:49         ` Rik van Riel
2018-08-29 16:14           ` Andy Lutomirski
2018-08-29 15:47 Andy Lutomirski
2018-08-29 16:06 ` Rik van Riel
2018-08-29 18:56 ` Nadav Amit
2018-08-30 13:36   ` Thomas Gleixner
2018-08-30 14:21     ` Andy Lutomirski
2018-08-30 14:27       ` Thomas Gleixner

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