Bug#544525: linux-image-2.6.26-2-xen-686: xenwatch kerrnel oops after failed attempt to add block device
Package: linux-image-2.6.26-2-xen-686
Version: 2.6.26-17lenny2
Severity: normal
For our xen VMs the kernel gives the attach oops when I try to add a new
block device to a domU and this attempt fails because of not available
loop devices.
The command (with output) used to add the device was:
====================
sudo xm block-attach callweaver file:/vm/pv-kernel/modules.img hdb2 r
Error: Device 834 (vbd) could not be connected. Failed to find an unused loop device
Usage: xm block-attach <Domain> <BackDev> <FrontDev> <Mode> [BackDomain]
Create a new virtual block device.
====================
While the missing loop device is a problem of the dom0 system the kernel oops
occurs in the domU.
The kernel oops didn't crash the machine, so I set severity to normal. The
dom0 is running Lenny with an x86_64 kernel 2.6.26-2+schedpatch.1-xen-amd64,
the standard debian xen kernel with an applied patch against some scheduler
bugs. I don't think the bug is caused by this patch, but if required I could
try to reproduce it with the standard kernel on the dom0 machine.
# uname -a
Linux callweaver 2.6.26-2-xen-686 #1 SMP Fri Aug 14 04:00:01 UTC 2009 i686 GNU/L
inux
===================
[661323.371745] BUG: unable to handle kernel NULL pointer dereference at 00000000
[661323.371759] IP: [<c024a3e4>] backend_changed+0x17d/0x1e2
[661323.371772] *pdpt = 0000000081473027 *pde = 0000000000000000
[661323.371781] Oops: 0000 [#1] SMP
[661323.371787] Modules linked in: ext3 jbd mbcache dm_mirror dm_log dm_snapshot
dm_mod raid10 raid1 md_mod thermal_sys
[661323.371807]
[661323.371811] Pid: 19, comm: xenwatch Not tainted (2.6.26-2-xen-686 #1)
[661323.371817] EIP: 0061:[<c024a3e4>] EFLAGS: 00010246 CPU: 0
[661323.371824] EIP is at backend_changed+0x17d/0x1e2
[661323.371830] EAX: c6b52800 EBX: c6b52800 ECX: c024a267 EDX: 00000000
[661323.371836] ESI: c1120000 EDI: c6b52800 EBP: 00000000 ESP: c7c95f80
[661323.371843] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0069
[661323.371850] Process xenwatch (pid: 19, ti=c7c94000 task=c7c8a900 task.ti=c7c
94000)
[661323.371856] Stack: c02408f8 00000000 c229bc80 c0336772 c6b52800 c3c50f80 c03
6f7e4 00000000
[661323.371873] c0242a3a c3c50e80 c6b52810 c3c50e80 c0241478 00000000 c02
41b18 c0241c4d
[661323.371889] 00000000 c7c8a900 c012ec88 c7c95fcc c7c95fcc 00000000 c01
2ebc5 c012eb8d
[661323.371905] Call Trace:
[661323.371911] [<c02408f8>] xenbus_read_driver_state+0x1c/0x2f
[661323.371922] [<c0242a3a>] otherend_changed+0x63/0x67
[661323.371930] [<c0241478>] xenwatch_handle_callback+0x12/0x41
[661323.371939] [<c0241b18>] xenwatch_thread+0x0/0x14b
[661323.371946] [<c0241c4d>] xenwatch_thread+0x135/0x14b
[661323.371954] [<c012ec88>] autoremove_wake_function+0x0/0x2d
[661323.371963] [<c012ebc5>] kthread+0x38/0x5f
[661323.371970] [<c012eb8d>] kthread+0x0/0x5f
[661323.371976] [<c010425f>] kernel_thread_helper+0x7/0x10
[661323.371985] =======================
[661323.371989] Code: 03 05 c4 b1 35 c0 c6 40 01 00 80 38 00 74 05 e8 e6 25 ff f
f 8b 46 04 e8 68 ca f8 ff c7 86 dc 13 00 00 01 00 00 00 eb 60 8b 56 04 <8b> 02 c
1 e0 14 0b 42 04 e8 78 80 f4 ff 85 c0 89 c3 75 10 68 b7
[661323.372065] EIP: [<c024a3e4>] backend_changed+0x17d/0x1e2 SS:ESP 0069:c7c95f
80
[661323.372080] ---[ end trace 981edaec6b11ee62 ]---
===================
-- System Information:
Debian Release: lenny/sid
APT prefers stable
APT policy: (500, 'stable')
Architecture: i386 (i686)
Kernel: Linux 2.6.26-2-xen-686 (SMP w/1 CPU core)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/bash
Versions of packages linux-image-2.6.26-2-xen-686 depends on:
ii initramfs-tools 0.92o tools for generating an initramfs
ii linux-modules-2.6.26-2-x 2.6.26-17lenny2 Linux 2.6.26 modules on i686
Versions of packages linux-image-2.6.26-2-xen-686 recommends:
ii libc6-xen 2.7-10 GNU C Library: Shared libraries [X
Versions of packages linux-image-2.6.26-2-xen-686 suggests:
pn grub <none> (no description available)
pn linux-doc-2.6.26 <none> (no description available)
-- no debconf information
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