[DRBD-user] Kernel Dump / Invalid Null Pointer drbd 0.7.23 together with vServer

Lars Ellenberg lars.ellenberg at linbit.com
Mon Apr 23 10:14:52 CEST 2007

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

On Mon, Apr 23, 2007 at 09:57:54AM +0200, Oliver Welter wrote:
> Hi Lars
> >> Worked fine the last year, now after the update I get kernel oopes when 
> >> I try to send the device to secondary state - the whole mount operation 
> >> is executed in the virtual context of the guest - running it on the root 
> >> host works fine.
> > 
> > then my guess is that either that patch breaks/changes
> > something fundamentally, and drbd would need to be adjusted to match
> > that change, or you did something stupid and compiled drbd against
> > a non-matching kernel, causing the drbd module and your kernel to be
> > ABI incompatible, and for some reason the safety net of insmod does
> > not catch the ABI incompatibility and loads it anyways.
> Hmm, I didnt go to deep into the stuff but the two patches dont seem to
> conflict. An ABI incomp is impossible as I am running an non-modular
> kernel and patched the kernel tree directly.

still possible: maybe you got the drbd kernel patch wrong.
the patch applies does not mean the patch is correct.
also there are a few ifdefs in various places,
and it is likely that they do not get automatically
correctly adjusted for some in-kernel drbd build.

> Do you have any hints on how to debug? I tried 0.8. yesterday and that
> seems to work...this will harden the migration but if we cant fix it
> fast I guess I will upgrade

find out which pointer is NULL according to the bug,
find out why this could happen, and propose a patch.
I know this advice is not very useful.  sorry...

maybe it also helps to just compare the kernel config of the non-working
and the working setup. just in case, I have no evidence that this may be
related, but you do use 8K stacks, right?

: Lars Ellenberg                            Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH      Fax +43-1-8178292-82 :
: Vivenotgasse 48, A-1120 Vienna/Europe    http://www.linbit.com :
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