Public bug reported:
When setting up kernel crash dump and testing with SysRQ-C, the kexec
procedure does not reboot the second kernel in order to copy the vmcore
info.
Steps to reproduce the problem in a Quantal VM are :
1) setup console port
2) install linux-crashdump
3) Fix crashkernel=128Mb to avoid current limitation
4) fix vmcoreinfo bug (remove references to vmcoreinfo as per LP: #988512
5) recreate initramfs / grub
6) reboot
7) test crash
This will trigger the following panic but will not follow-up with kexec
loading the loaded kernel required to save the vmcore info :
root@QuantalSA-crash:~# echo c > /proc/sysrq-trigger
[ 23.740777] SysRq : Trigger a crash
[ 23.741555] BUG: unable to handle kernel NULL pointer dereference at
(null)
[ 23.743183] IP: [<ffffffff813e2c56>] sysrq_handle_crash+0x16/0x20
[ 23.744175] PGD 3bd7e067 PUD 3b933067 PMD 0
[ 23.744175] Oops: 0002 [#1] SMP
[ 23.744175] CPU 0
[ 23.744175] Modules linked in:
[ 23.744175] kvm ext2 snd_hda_intel microcode snd_hda_codec snd_hwdep
snd_pcm snd_timer snd soundcore virtio_balloon snd_page_alloc psmouse serio_ra
w i2c_piix4 mac_hid lp parport floppy
[ 23.744175]
[ 23.744175] Pid: 1218, comm: bash Not tainted 3.5.0-3-generic #3-Ubuntu
Bochs Bochs
[ 23.744175] RIP: 0010:[<ffffffff813e2c56>] [<ffffffff813e2c56>]
sysrq_handle_crash+0x16/0x20
[ 23.744175] RSP: 0018:ffff88003a979e28 EFLAGS: 00010096
[ 23.744175] RAX: 000000000000000f RBX: ffffffff81c7a020 RCX: 0000000000001aaf
[ 23.744175] RDX: 0000000000001aaf RSI: 0000000000000086 RDI: 0000000000000063
[ 23.744175] RBP: ffff88003a979e28 R08: 000000000000019e R09: 000000000000019d
[ 23.744175] R10: 0000000000038e4c R11: 0000000000000000 R12: 0000000000000063
[ 23.744175] R13: 0000000000000286 R14: 0000000000000004 R15: 0000000000000000
[ 23.744175] FS: 00007fed36a0f700(0000) GS:ffff88003fc00000(0000)
knlGS:0000000000000000
[ 23.744175] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 23.744175] CR2: 0000000000000000 CR3: 000000003b966000 CR4: 00000000000006f0
[ 23.744175] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 23.744175] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 23.744175] Process bash (pid: 1218, threadinfo ffff88003a978000, task
ffff88003d7adc00)
[ 23.744175] Stack:
[ 23.744175] ffff88003a979e68 ffffffff813e3301 ffff88003d7adc00
0000000000000002
[ 23.744175] ffff88003a345f00 ffffffff813e33e0 ffff88003c80d380
0000000000000002
[ 23.744175] ffff88003a979e98 ffffffff813e342a ffff88003aad1000
0000000001ea9408
[ 23.744175] Call Trace:
[ 23.744175] [<ffffffff813e3301>] __handle_sysrq+0xb1/0x190
[ 23.744175] [<ffffffff813e33e0>] ? __handle_sysrq+0x190/0x190
[ 23.744175] [<ffffffff813e342a>] write_sysrq_trigger+0x4a/0x50
[ 23.744175] [<ffffffff811e2112>] proc_reg_write+0x82/0xc0
[ 23.744175] [<ffffffff8118214c>] vfs_write+0xac/0x180
[ 23.744175] [<ffffffff8118247a>] sys_write+0x4a/0x90
[ 23.744175] [<ffffffff8167cd29>] system_call_fastpath+0x16/0x1b
[ 23.744175] Code: ff ff 45 01 f4 45 39 65 2c 75 cd 4c 89 ef e8 92 f7 ff ff
eb c3 55 48 89 e5 66 66 66 66 90 c7 05 f1 2a a2 00 01 00 00 00 0f ae f8 <
c6> 04 25 00 00 00 00 01 5d c3 55 48 89 e5 53 48 83 ec 08 66 66
[ 23.744175] RIP [<ffffffff813e2c56>] sysrq_handle_crash+0x16/0x20
[ 23.744175] RSP <ffff88003a979e28>
[ 23.744175] CR2: 0000000000000000
Identical steps done in a Precise VM will trigger kexec
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu quantal (development branch)
Release: 12.10
Codename: quantal
ubuntu@QuantalSA-crash:~$ uname -a
Linux QuantalSA-crash 3.5.0-3-generic #3-Ubuntu SMP Mon Jul 2 16:49:22 UTC 2012
x86_64 x86_64 x86_64 GNU/Linux
** Affects: linux (Ubuntu)
Importance: Undecided
Status: Incomplete
** Tags: quantal
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https://bugs.launchpad.net/bugs/1022561
Title:
Quantal : kexec kernel not triggered when kernel panics
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