Re: [GIT PULL] x86/uapi for 3.8

From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Jan Beulich <jbeulich@suse.com>,
	Matt Fleming <matt.fleming@intel.com>,
	David Howells <dhowells@redhat.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
	Arnd Bergmann <arnd@arndb.de>, Dave Jones <davej@redhat.com>,
	Ingo Molnar <mingo@elte.hu>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [GIT PULL] x86/uapi for 3.8
Date: Sat, 15 Dec 2012 21:06:12 +0100	[thread overview]
Message-ID: <20121215200612.GA221@x4> (raw)
In-Reply-To: <CA+55aFxi5SnacGoHzHuth4PvTRQQWA5kWM+D2Mn+FgV4VGYADQ@mail.gmail.com>

On 2012.12.15 at 11:58 -0800, Linus Torvalds wrote:
> On Sat, Dec 15, 2012 at 11:41 AM, H. Peter Anvin <hpa@zytor.com> wrote:
> >
> > Matt is on vacation, and I'm partly offline for the weekend, but that
> > definitely seems suspicious.  Do we have a memory map of the affected
> > machine(s)?
> 
> Here's mine.
> 
>   e820: BIOS-provided physical RAM map:
>   BIOS-e820: [mem 0x0000000000000000-0x000000000009e7ff] usable
>   BIOS-e820: [mem 0x000000000009e800-0x000000000009ffff] reserved
>   BIOS-e820: [mem 0x00000000000e4000-0x00000000000fffff] reserved
>   BIOS-e820: [mem 0x0000000000100000-0x00000000bdc6ffff] usable
>   BIOS-e820: [mem 0x00000000bdc70000-0x00000000bdc87fff] ACPI data
>   BIOS-e820: [mem 0x00000000bdc88000-0x00000000bdcdbfff] ACPI NVS
>   BIOS-e820: [mem 0x00000000bdcdc000-0x00000000bfffffff] reserved
>   BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
>   BIOS-e820: [mem 0x00000000ff800000-0x00000000ffffffff] reserved
>   BIOS-e820: [mem 0x0000000100000000-0x00000001fbffffff] usable
>   BIOS-e820: [mem 0x00000001fc000000-0x00000001ffffffff] reserved
>   BIOS-e820: [mem 0x0000000200000000-0x000000023fffffff] usable
> 
> but as mentioned, there's bound to be some particular kernel layout
> that triggers this, because I definitely ran a few kernels with that
> commit in it without problems (and clearly other people are too).
> Looking at my boot log, I had successful boots with both 6a57d104c8cb
> and c2714334b944, which contains that commit.
> 
> It might also be that it causes some massive corruption at boot time,
> but it then requires that that particular memory is actually used. So
> maybe it's not so much about the memory map except indirectly.
> 
> But that commit *does* look a lot more likely than the things I looked at.
> 
> Markus, how did you happen to pinpoint that particular commit? Is it
> entirely repeatable for you?

Yes, although at one point during bisecting the BUG disappeared and the
screen went simply black during boot and X never started. I marked this
as bad and continued the bisection.

Here is my mem-map:

e820: BIOS-provided physical RAM map:
BIOS-e820: [mem 0x0000000000000100-0x000000000009fbff] usable
BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
BIOS-e820: [mem 0x00000000000e6000-0x00000000000fffff] reserved
BIOS-e820: [mem 0x0000000000100000-0x00000000dfe8ffff] usable
BIOS-e820: [mem 0x00000000dfe90000-0x00000000dfea7fff] ACPI data
BIOS-e820: [mem 0x00000000dfea8000-0x00000000dfecffff] ACPI NVS
BIOS-e820: [mem 0x00000000dfed0000-0x00000000dfefffff] reserved
BIOS-e820: [mem 0x00000000fff00000-0x00000000ffffffff] reserved
BIOS-e820: [mem 0x0000000100000000-0x000000021fffffff] usable

-- 
Markus