[DRBD-user] BUG: unable to handle kernel NULL pointer dereference at 0...037 (drbd-8.3.2)

Lars Ellenberg lars.ellenberg at linbit.com
Fri Sep 25 11:36:36 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On Thu, Sep 24, 2009 at 09:15:40PM +0200, Thomas Reinhold wrote:
>
> Am 21.09.2009 um 13:35 schrieb Lars Ellenberg:
>>
>>
>> something that Oopses at offset 0 of some function is most likely a  
>> compile problem,
>> i.e. I suggest that your kernel and drbd module do not fit together.
>
>
>
> Hi,
>
> I have experienced a similar looking problem on a cluster system also  
> using Ubuntu:

"Similar looking"
as in "just some oops and hexnumbers and other gobledeegook"

Not similar looking at all in the details of the oops.

PieterB had some NULL dereference at drbd_connect+0x0,
at a zero offset to a function.
Which is extremely unlikely to be a coding bug that seldom triggers.

Your oops is ...:

> Systems (identically configured): Ubuntu 9.04 Server x86_64 server with 
> Kernel 2.6.28-15-server (standard distro kernel)
> DRBD: as included in Ubuntu Server  (8.3.0)

> Usage: KVM host (Software Raid 1 -> DRBD -> LVM -> KVM VMs)
>
>
> The problem appeared on the secondary directly after issuing "drbdadm  
> verify all":
>
>> Sep 23 17:04:58 cluster2 kernel: [ 1579.818149] drbd0: conn( Connected 
>> -> VerifyT )
>> Sep 23 17:04:59 cluster2 kernel: [ 1579.820914] drbd1: conn( Connected 
>> -> VerifyT )
>> Sep 23 17:04:59 cluster2 kernel: [ 1579.830819] BUG: unable to handle 
>> kernel NULL pointer dereference at 0000000000000030
>> Sep 23 17:04:59 cluster2 kernel: [ 1579.830877] IP:  
>> [<ffffffffa0105373>] w_e_end_ov_req+0x43/0x1a0 [drbd]

There.  w_e_end_ov_req+0x43, this is a place and offset where it is much
more likely to be a coding bug. It may even be fixed already.

Please reproduce with 8.3.3.

> I had done some pretty intensive testing (Bonnie++, dd, etc.) before and 
> everything was ok...could not reproduce the problem afterwards, either.
>
>
> What bothers me (apart from the bug) is the following:
>
>   - Your changelog says that compatibility with Linux 2.6.27, 2.6.28 and 
> 2.6.29 was added in 8.3.1, while Ubuntu Server with kernel 2.6.28 ships 
> with DRBD 8.3.0. Btw., the DRBD module appear to has been compiled in 
> January, while the kernel was compiled in August.
>
>
> Did the Ubuntu guys really screw it up that bloody? And if so, am I
> the only one using the DRBD version included in Ubuntu server??

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
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