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Message-ID: <550A16E6.70001@message-id.googlemail.com>
Date: Thu, 19 Mar 2015 01:23:02 +0100
From: Stefan Seyfried <stefan.seyfried@...glemail.com>
To: Andy Lutomirski <luto@...capital.net>
CC: Jiri Kosina <jkosina@...e.cz>,
Denys Vlasenko <dvlasenk@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Takashi Iwai <tiwai@...e.de>, X86 ML <x86@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>
Subject: Re: PANIC: double fault, error_code: 0x0 in 4.0.0-rc3-2, kvm related?
Am 19.03.2015 um 00:22 schrieb Andy Lutomirski:
> On Wed, Mar 18, 2015 at 3:40 PM, Andy Lutomirski <luto@...capital.net> wrote:
>> Yes, it's userspace. Thanks for checking, though.
>
> One more stupid hunch:
>
> Can you do:
> x/21xg ffff8801013d4f58
>
> If I counted right, that'll dump task_pt_regs(current).
That's all zeroes:
crash> x /21xg 0xffff8801013d4f58
0xffff8801013d4f58: 0x0000000000000000 0x0000000000000000
0xffff8801013d4f68: 0x0000000000000000 0x0000000000000000
0xffff8801013d4f78: 0x0000000000000000 0x0000000000000000
0xffff8801013d4f88: 0x0000000000000000 0x0000000000000000
0xffff8801013d4f98: 0x0000000000000000 0x0000000000000000
0xffff8801013d4fa8: 0x0000000000000000 0x0000000000000000
0xffff8801013d4fb8: 0x0000000000000000 0x0000000000000000
0xffff8801013d4fc8: 0x0000000000000000 0x0000000000000000
0xffff8801013d4fd8: 0x0000000000000000 0x0000000000000000
0xffff8801013d4fe8: 0x0000000000000000 0x0000000000000000
0xffff8801013d4ff8: 0x0000000000000000
But maybe you counted wrong (or I'm reading arch/x86/include/asm/processor.h wrong, which is at least as likely...).
#define task_pt_regs(tsk) ((struct pt_regs *)(tsk)->thread.sp0 - 1)
=> I have the task_struct readily available decoded in the crash utility.
crash> task, search for thread, in thread:
sp0 = 18446612136629993472
crash> eval 18446612136629993472
hexadecimal: ffff8801013d8000 (18014269664677728KB)
....
crash> print *(struct pt_regs *)(18446612136629993472 - sizeof(struct pt_regs))
$20 = {
r15 = 18446744071585666077,
r14 = 16,
r13 = 582,
r12 = 18446612136629993352,
bp = 24,
bx = 18446744071585666061,
r11 = 582,
r10 = 10760856,
r9 = 140712613762160,
r8 = 140735967861216,
ax = 1,
cx = 140712476030103,
dx = 140712613782304,
si = 1,
di = 140712589295616,
orig_ax = 209,
ip = 140712571864823,
cs = 51,
flags = 582,
sp = 140735967860552,
ss = 43
}
=>
r15 = ffffffff8168141d
r12 = ffff8801013d7f88
bx = ffffffff8168140d
r9 = 7ffa355bd470
ip = 7ffa32dc86f7
sp = 7fffa55f1748
looks somehow legit, to my totally untrained eye (ip and sp actually).
I'm off to bed now (01:20 around here ;), will be back in about 7 hours.
Best regards,
Stefan
--
Stefan Seyfried
Linux Consultant & Developer -- GPG Key: 0x731B665B
B1 Systems GmbH
Osterfeldstraße 7 / 85088 Vohburg / http://www.b1-systems.de
GF: Ralph Dehner / Unternehmenssitz: Vohburg / AG: Ingolstadt,HRB 3537
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