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Date: Thu, 19 Mar 2015 07:24:48 +0100
From: Stefan Seyfried <stefan.seyfried@googlemail.com>
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To: Andy Lutomirski <luto@amacapital.net>
CC: Jiri Kosina <jkosina@suse.cz>, Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Takashi Iwai <tiwai@suse.de>, X86 ML <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>
Subject: Re: PANIC: double fault, error_code: 0x0 in 4.0.0-rc3-2, kvm related?
References: <5505400B.8050300@message-id.googlemail.com> <s5hr3smfl11.wl-tiwai@suse.de> <s5hy4mukxpj.wl-tiwai@suse.de> <s5h4mpi5hbv.wl-tiwai@suse.de> <CALCETrVCMEcCOHZ35LneCU6uGH+W5SF0groKbUGp2zTjWpzB0w@mail.gmail.com> <5509CBF7.3040602@message-id.googlemail.com> <CALCETrU2R020HVniX2sczxexPO2qhEPbS++9DXzcxeycgxoGQg@mail.gmail.com> <CA+55aFwT4BJVR10i2Cm8pMH0UGd-J3EwnEUYKf3BWTM0awebbA@mail.gmail.com> <5509F161.3010101@redhat.com> <CALCETrXZvSiT41+AYAPizSsGZ_=O=7wmb+Lwo_ChEZySxUnH-A@mail.gmail.com> <alpine.LRH.2.00.1503182320490.13021@twin.jikos.cz> <CALCETrVnJHXhz81QCr7qmm0uwdw2t0EWe_zUw4E7bZB2WXQNTQ@mail.gmail.com> <5509FE69.3060002@message-id.googlemail.com> <CALCETrVOEWt2RgbNC4xpuJaa-1avn9LUM6zXBQq9K_nsHT3P6w@mail.gmail.com> <CALCETrUYjchZaNwFdjo=BPbmyyo5vgAW=T6nU6-TYEWq4338pw@mail.gmail.com> <550A16E6.70001@message-id.googlemail.com> <CALCETrXprbgQ_-ED+pjqXTH10LrG=SpkWt_xkDsu_vpX02Hk5w@mail.gmail.com>
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Good Morning :-)

Am 19.03.2015 um 01:57 schrieb Andy Lutomirski:

> Stefan, do you happen to know whether your disassembly of page_fault
> came from the instructions in memory or if they came from the vmlinux
> file?  Not that I have any relevant ideas there.

I think they came from memory. At least, the disassemble in crash...
crash> disassemble page_fault
Dump of assembler code for function page_fault:
   0xffffffff816834a0 <+0>:     data32 xchg %ax,%ax
   0xffffffff816834a3 <+3>:     data32 xchg %ax,%ax
   0xffffffff816834a6 <+6>:     data32 xchg %ax,%ax
   0xffffffff816834a9 <+9>:     sub    $0x78,%rsp
   0xffffffff816834ad <+13>:    callq  0xffffffff81683620 <error_entry>
   0xffffffff816834b2 <+18>:    mov    %rsp,%rdi
   0xffffffff816834b5 <+21>:    mov    0x78(%rsp),%rsi
   0xffffffff816834ba <+26>:    movq   $0xffffffffffffffff,0x78(%rsp)
   0xffffffff816834c3 <+35>:    callq  0xffffffff810504e0 <do_page_fault>
   0xffffffff816834c8 <+40>:    jmpq   0xffffffff816836d0 <error_exit>
End of assembler dump.

...is different than the one from loading vmlinux in gdb:

Reading symbols from vmlinux-4.0.0-rc3-2.gd5c547f-desktop...done.
Reading symbols from /usr/lib/debug/boot/vmlinux-4.0.0-rc3-2.gd5c547f-desktop.debug...done.
(gdb) disassemble page_fault
Dump of assembler code for function page_fault:
   0xffffffff816834a0 <+0>:     data16 xchg %ax,%ax
   0xffffffff816834a3 <+3>:     callq  *0x7a5b07(%rip)        # 0xffffffff81e28fb0 <pv_irq_ops+48>
   0xffffffff816834a9 <+9>:     sub    $0x78,%rsp
   0xffffffff816834ad <+13>:    callq  0xffffffff81683620 <error_entry>
   0xffffffff816834b2 <+18>:    mov    %rsp,%rdi
   0xffffffff816834b5 <+21>:    mov    0x78(%rsp),%rsi
   0xffffffff816834ba <+26>:    movq   $0xffffffffffffffff,0x78(%rsp)
   0xffffffff816834c3 <+35>:    callq  0xffffffff810504e0 <do_page_fault>
   0xffffffff816834c8 <+40>:    jmpq   0xffffffff816836d0 <error_exit>
End of assembler dump.

Best regards,

	Stefan
-- 
Stefan Seyfried
Linux Consultant & Developer -- GPG Key: 0x731B665B

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