Re: random crash in post_kvm_run()

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/28/2010 12:28 PM, BuraphaLinux Server wrote:
> Hello,
>
>      I have tried qemu_kvm 0.12.4 release and also git from about 1/2
> an hour ago.  In both cases, I crash in the post_kvm_run() function on
> the line about:
>
> pthread_mutex_lock(&qemu_mutex);
>
> The command I use to run qemu worked great with
> glibc-2.11.1,linux-2.6.32.14,and gcc-4.4.3,
> but I have upgraded to glibc-2.11.2, linux-2.6.34, and gcc-4.4.4 and get this:
>
> (gdb) bt
> #0  post_kvm_run (kvm=0x84cde04, env=0x84e7168)
>      at /tmp/qemu-kvm-201006282359/qemu-kvm.c:566
> #1  0x08086ccf in kvm_run (env=0x84e7168)
>      at /tmp/qemu-kvm-201006282359/qemu-kvm.c:619
> #2  0x080882d0 in kvm_cpu_exec (env=0x84e7168)
>      at /tmp/qemu-kvm-201006282359/qemu-kvm.c:1238
> #3  0x08088cf6 in kvm_main_loop_cpu (env=0x84e7168)
>      at /tmp/qemu-kvm-201006282359/qemu-kvm.c:1495
> #4  0x08088e72 in ap_main_loop (_env=0x84e7168)
>      at /tmp/qemu-kvm-201006282359/qemu-kvm.c:1541
> #5  0x55598690 in start_thread () from /lib/libpthread.so.0
> #6  0x55a8ca7e in clone () from /lib/libc.so.6
> (gdb) list
> 561     in /tmp/qemu-kvm-201006282359/qemu-kvm.c
> (gdb) print qemu_mutex
> $1 = {__data = {__lock = 0, __count = 0, __owner = 0, __kind = 0,
>      __nusers = 0, {__spins = 0, __list = {__next = 0x0}}},
>    __size = '\000'<repeats 23 times>, __align = 0}
> (gdb)
>
> I rebuilt the kernel, then glibc, then the entire graphics stack, then
> qemu_kvm to try and be sure I have no problems about headers.  All my
> other software works, but qemu_kvm does not.  About 1 time in 10 it
> will actually run fine, but the other times it will crash as shown.  I
> use a dedicated LV for this.  I have a 32bit userland with a 64bit
> kernel.

This is an unusual configuration.  Is it possible try try a 64-bit userland?

Regards,

Anthony Liguori

>    Here is the script I use:
>
> #! /sbin/bash
> INSTANCE=0
> NAME=VM${INSTANCE}
> FAKEDISK=/dev/mapper/vmland-vmdisk${INSTANCE}
> ((MACNO=22+INSTANCE))
> ulimit -S -c unlimited
> echo qemu-system-x86_64 \
>    -cpu core2duo -smp 2 -m 512 \
>    -vga std \
>    -vnc :${INSTANCE} -monitor stdio \
>    -localtime -usb -usbdevice mouse \
>    -net nic,vlan=0,model=rtl8139,macaddr=DE:AD:BE:EF:25:${MACNO} \
>    -net tap,ifname=tap${INSTANCE},script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
> \
>    -name ${NAME} \
>    -hda ${FAKEDISK} \
>    -boot c
> qemu-system-x86_64 \
>    -cpu core2duo -smp 2 -m 512 \
>    -vga std \
>    -vnc :${INSTANCE} -monitor stdio \
>    -localtime -usb -usbdevice mouse \
>    -net nic,vlan=0,model=rtl8139,macaddr=DE:AD:BE:EF:25:${MACNO} \
>    -net tap,ifname=tap${INSTANCE},script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
> \
>    -name ${NAME} \
>    -hda ${FAKEDISK} \
>    -boot c
> # just in case
> /usr/sbin/brctl delif br0 tap${INSTANCE}
>
> The bridging and taps all worked before.   The CPU is a core i7 950,
> I've got 12GB of RAM, and I'm going nuts trying to debug this.  Since
> it sometimes works, I wonder if there is some uninitialized variable
> that sometimes is set so I get lucky but usually is set where things
> crash.
>
> I don't want to place blame, I just want to get it working.  Any
> hints?  I'm not subscribed, but the page at
> http://www.linux-kvm.org/page/Lists,_IRC said it's ok to send a
> message anyway.  Please cc: me so I get a copy, or if I need to join
> the list please tell me.
>
> I compile it all from source (similar to linux from scratch) so there
> is no upstream distro to go ask for help.  Since everything else
> works, I suspect something strange in qemu_kvm.  I did google a lot
> but found nothing helpful.
>
> The ISO image used works on real hardware, and uses the same kernel
> and userland.  The isolinux shows the menu and works great, but when
> it is time to boot the kernel I get the crash.
>
> The kernel modules kvm and kvm_intel are loaded when I try to start qemu_kvm.
>
> The /var/log/messages just shows this:
>
> Jun 29 00:05:47 banpuk kernel: [20299.236926] qemu-system-x86[31375]:
> segfault at 14 ip 0000000008086a64 sp 000000005601e180 error 4 in
> qemu-system-x86_64[8048000+256000]
>
> The /var/log/syslog show this:
>
> Jun 29 00:06:00 banpuk kernel: [20312.302498] kvm: 31383: cpu0
> unhandled wrmsr: 0x198 data 0
> Jun 29 00:06:00 banpuk kernel: [20312.302606] kvm: 31383: cpu1
> unhandled wrmsr: 0x198 data 0
>
> JGH
> --
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