Kernel Bug Tracker – Bug 11951
Early boot failure for 2.6.28-rc: NULL pointer deref stemming from scheduler_tick
Last modified: 2008-11-09 10:52:21 UTC
Latest working kernel version: 2.6.27
Earliest failing kernel version: 2.6.28-rc1
Distribution: Ubuntu Hardy
Hardware Environment: Dual Processor Pentium 4 Xeon Whitebox
Problem Description: oops in early boot
My fileserver boots under 2.6.27, but it is failing to boot on
2.6.28-rc2. It took me a while to bisect, so after I finished the
bisection, I retested with the latest mainline
(v2.6.28-rc3-54-g75fa677), and the problem still shows up.
Essentially, the system panics in early boot, resulting in multiple
oops. I finally was able get the very first oops, and the image of
that oops can be found here:
From the console snapshot, it looks like two CPU simultaneously
OOPS'ed with a:
BUG: unable to handle kernel NULL dereference at 00000000
BUG: unable to handle kernel NULL dereference at 00000038
On the stack is "scheduler_tick+0x83/0x15f"
When doing a bisection, the last good commit (i.e., the last one which
I can boot on my system) is git id: d6c88a50 (which preceeds 2.6.28-rc1).
The first bad git ID is:
Author: Thomas Gleixner <firstname.lastname@example.org>
Date: Wed Oct 15 15:27:23 2008 +0200
genirq: revert dynarray
Revert the dynarray changes. They need more thought and polishing.
Signed-off-by: Thomas Gleixner <email@example.com>
... but in fact, the failure is different from the above messages.
The failure is once again in early boot, but the oops message is quite
The failure was in kmem_cache_alloc+0xab/0xc4, called by
Walking forwards, the first git ID which shows the same failure as
what shows up in 2.6.28-rc2 and 2.6.28-rc3 is git ID: 92b29b8, which
apparently is a merge of the tracing-v28-for-linus branch. Because
there were two failures back-to-back, it's possible either I or git
bisect got confused, since normally the bisect normally doesn't
terminate on a merge commit. I'll try double-checking the two
ancestors of the merge commit by hand, but in the meantime I thought
I'd send what I have in case it rings a bell.
Again, my system is totally failing to boot since 2.6.28-rc1. This is
a Aberdeen (white box) fileserver, with a SuperMicro X6DH8-XG2
motherboard, with two Pentium 4 Xeon 3.0GHz with hyperthreading.
Created attachment 18664 [details]
Created attachment 18665 [details]
Boot log from a successful boot of 2.6.27 kernel
Created attachment 18666 [details]
Kernel config file from a failing kernel during the bisection
Created attachment 18667 [details]
The cpuinfo file from my system
Created attachment 18668 [details]
/proc/timer_list from my 2.6.27 kernel
Note: The LKML thread discussing this bug can be found here:
References : http://lkml.org/lkml/2008/11/4/450
Handled-By : Yinghai Lu <firstname.lastname@example.org>
Patch : http://lkml.org/lkml/2008/11/4/431
Patch : http://lkml.org/lkml/2008/11/5/81