Re: random crash in post_kvm_run()

[BuraphaLinux Server <buraphalinuxserver@gmail.com>]

Reply inline.

On 6/29/10, Brian Jackson <iggy@theiggy.com> wrote:
> On Monday, June 28, 2010 12:28:52 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
>> $1 = {__data = {__lock = 0, __count = 0, __owner = 0, __kind = 0,
>>     __nusers = 0, {__spins = 0, __list = {__next = 0x0}}},
>>   __size = '\000' <repeats 23 times>, __align = 0}
>> (gdb)
>>
>> I rebuilt the kernel, then glibc, then the entire graphics stack, then
>> qemu_kvm to try and be sure I have no problems about headers.  All my
>> other software works, but qemu_kvm does not.  About 1 time in 10 it
>> will actually run fine, but the other times it will crash as shown.  I
>> use a dedicated LV for this.  I have a 32bit userland with a 64bit
>> kernel.  Here is the script I use:
>>
>> #! /sbin/bash
>> INSTANCE=0
>> NAME=VM${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-ifdow
>> n \
>>   -name ${NAME} \
>>   -hda ${FAKEDISK} \
>>   -boot c
>> qemu-system-x86_64 \
>>   -cpu core2duo -smp 2 -m 512 \
>
>
> try without -cpu core2duo
>

I tried without that option, but I get the same crash.  Thank you for
the suggestion however, and I guess that rules out problems with the
'-cpu' option.

>>   -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-ifdow
>> n \
>>   -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