Re: 2.6.11.8 + UML/x86_64 (2.6.12-rc3+) = oops

Antoine Martin
2005-05-08T15:03:47Z

> (..)
> That is a wrmsr to 0x00000000c0000102 (KERNEL_GS_BASE), the code
> is trying to write 0x0000c8e816000002 into it. That is a non canonical
> address, which causes the GPF.
>
> The strange thing is that the kernel should have rejected it in
> the first place. The code to allow user space to set kernel gs
> checks for the address being > TASK_SIZE and TASK_SIZE is 0x800000000000.
> It should have rejected it in the first place.
>
> Are you sure you did not apply any strange UML related patches
> to the host kernel? Maybe those are buggy.
The only extra patch applied on top of what is on the web page (as per
Jeff's instructions) is the mconsole-exec patch, and AFAIK it wouldn't
affect the code above.

Alexander Nyberg is also experiencing crashes, aren't you?
Just un-compressing portage (20MB .tar.bz2) on the root_fs image posted
earlier caused a different kind of mis-behaviour, the guest lost network
connectivity, cpu usage shot up on the host (load > 10 now), and I found
this in the host log:
kernel: segfault at 00000000df2948d0 rip 00000000601e5beb
rsp00000000df2948d0 error 4
(same kernel as earlier crashes...)
That's on a different box, running a different host kernel (FC3 2.6.9-?)

The really weird thing is that the processes are still running, but ps
-ef shows an empty string in place of the process name:
(and the terminal which launched the instance got control back)
I am now rebuilding a new kernel on another test box, let me know what
to do to provide better debug information.

# ps -ef
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 13:27 ? 00:00:00 init [3]
root 2 1 0 13:27 ? 00:00:00 [ksoftirqd/0]
root 3 1 0 13:27 ? 00:00:00 [events/0]
root 4 3 0 13:27 ? 00:00:00 [khelper]
root 5 3 0 13:27 ? 00:00:00 [kacpid]
root 27 3 0 13:27 ? 00:00:00 [kblockd/0]
root 28 1 0 13:27 ? 00:00:00 [khubd]
root 40 3 0 13:27 ? 00:00:00 [pdflush]
root 41 3 0 13:27 ? 00:00:00 [pdflush]
root 43 3 0 13:27 ? 00:00:00 [aio/0]
root 42 1 0 13:27 ? 00:00:00 [kswapd0]
root 115 1 0 13:27 ? 00:00:00 [kseriod]
root 183 3 0 13:27 ? 00:00:00 [ata/0]
root 185 1 0 13:27 ? 00:00:00 [scsi_eh_0]
root 186 1 0 13:27 ? 00:00:00 [scsi_eh_1]
root 202 1 0 13:27 ? 00:00:00 [kjournald]
root 1025 1 0 13:27 ? 00:00:00 udevd
root 1261 1 0 13:27 ? 00:00:00 [khpsbpkt]
root 1290 1 0 13:27 ? 00:00:00 [knodemgrd_0]
root 1453 1 0 13:27 ? 00:00:00 [kjournald]
root 1454 1 0 13:27 ? 00:00:00 [kjournald]
root 1693 1 0 13:28 ? 00:00:00 syslogd -m 0
root 1697 1 0 13:28 ? 00:00:00 klogd -x
nobody 1737 1 0 13:28 ? 00:00:00 mDNSResponder
root 1755 1 0 13:28 ? 00:00:00 /usr/sbin/acpid
root 1770 1 0 13:28 ? 00:00:00 /usr/sbin/sshd
root 1779 1 0 13:28 ? 00:00:00 gpm -m /dev/input/mice
-t imps2
root 1809 1 0 13:28 ? 00:00:00 crond
dbus 1833 1 0 13:28 ? 00:00:00 dbus-daemon-1 --system
root 1842 1 0 13:28 ? 00:00:00 hald
root 1849 1 0 13:28 ? 00:00:00 login -- root
root 1850 1 0 13:28 tty2 00:00:00 /sbin/mingetty tty2
root 1851 1 0 13:28 tty3 00:00:00 /sbin/mingetty tty3
root 1852 1 0 13:28 tty4 00:00:00 /sbin/mingetty tty4
root 1853 1 0 13:28 tty5 00:00:00 /sbin/mingetty tty5
root 1854 1 0 13:28 tty6 00:00:00 /sbin/mingetty tty6
root 2270 1849 0 13:31 tty1 00:00:00 -bash
root 2312 1770 0 13:31 ? 00:00:00 sshd: root@pts/0
root 2314 2312 0 13:32 pts/0 00:00:00 -bash
root 2363 2314 19 13:36 pts/0 00:30:19 ./setiathome
root 4346 1770 0 15:03 ? 00:00:00 sshd: root@pts/1
root 4350 4346 0 15:03 pts/1 00:00:00 -bash
root 5291 4350 0 15:14 pts/1 00:00:00 tail
-f /var/log/messages /var/log/secure
root 6179 1 0 15:16 pts/0 00:00:35
root 7231 1 0 15:16 pts/0 00:00:35
root 7252 1 0 15:16 pts/0 00:00:35
root 7345 1 0 15:17 ? 00:00:00 /usr/sbin/dhcpd
root 7352 1 0 15:17 pts/0 00:00:34
root 7485 1 0 15:17 pts/0 00:00:34
root 7509 1 0 15:17 pts/0 00:00:34
root 7520 1770 0 15:18 ? 00:00:00 sshd: root@pts/2
root 7522 7520 0 15:18 pts/2 00:00:00 -bash
root 7561 7522 0 15:18 pts/2 00:00:00 ssh -v root@10.0.0.250
root 7563 1 1 15:18 pts/0 00:00:35
root 7571 1 1 15:18 pts/0 00:00:35
root 10302 1770 0 15:57 ? 00:00:00 sshd: root@pts/3
root 10304 10302 0 15:57 pts/3 00:00:00 -bash
root 10422 1 8 16:08 pts/0 00:00:38
root 10424 1 9 16:08 pts/0 00:00:42
root 10445 2314 0 16:16 pts/0 00:00:00 ps -ef