[libvirt-users] Kernel panic after kernel update

[Michael Ströder]

HI!

On one qemu-kvm instance a kernel update failed and booting the image is not
possible anymore (see below). A dozen other VMs are correctly working after the
upgrade. Anything I can quickly try to make it work again?

(This is not really a bad emergency case because I could simply re-install and
re-configure with ansible. But I'd like to learn about these cases...)

Ciao, Michael.

Loading Linux 4.8.12-1-default ...
[    0.651328] Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(0,0)
[    0.654408] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.12-1-default #1
[    0.656941] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014
[    0.661166]  0000000000000000 ffffffff813a4252 ffff9a5348c4d000 ffff9a5349957e60
[    0.664652]  ffffffff8118e3fa ffff9a5300000010 ffff9a5349957e70 ffff9a5349957e08
[    0.668124]  ffffffff8118e715 ffff9a5349957e78 0000000000000001 0000000000000000
[    0.671457] Call Trace:
[    0.672460]  [<ffffffff8102eefe>] dump_trace+0x5e/0x310
[    0.674389]  [<ffffffff8102f2cb>] show_stack_log_lvl+0x11b/0x1a0
[    0.676570]  [<ffffffff81030001>] show_stack+0x21/0x40
[    0.678480]  [<ffffffff813a4252>] dump_stack+0x5c/0x7a
[    0.680369]  [<ffffffff8118e3fa>] panic+0xd5/0x217
[    0.682169]  [<ffffffff81f56419>] mount_block_root+0x1fe/0x2c0
[    0.684285]  [<ffffffff81f56668>] prepare_namespace+0x12b/0x161
[    0.686439]  [<ffffffff81f56103>] kernel_init_freeable+0x1f6/0x20a
[    0.688675]  [<ffffffff816c727a>] kernel_init+0xa/0x100
[    0.690623]  [<ffffffff816d485f>] ret_from_fork+0x1f/0x40
[    0.696659] DWARF2 unwinder stuck at ret_from_fork+0x1f/0x40
[    0.698858]
[    0.699533] Leftover inexact backtrace:
[    0.699533]
[    0.701580]  [<ffffffff816c7270>] ? rest_init+0x90/0x90
[    0.703944] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range:
0xffffffff80000000-0xffffffffbfffffff)

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