Re: unexpected taint message

[Larry Finger]

On 12/16/2011 07:58 AM, Johannes Berg wrote:
> On Fri, 2011-12-16 at 07:53 -0600, Larry Finger wrote:
> > On 12/16/2011 06:30 AM, Johannes Berg wrote:
> > > On Fri, 2011-12-16 at 10:27 +0100, Arend van Spriel wrote:
> > > > To whoever may know,
> > > >
> > > > Upon loading our driver module I get the following message:
> > > >
> > > > kernel: [  344.805106] Disabling lock debugging due to kernel taint
> > > >
> > > > What exactly are the criteria for tainting? Our driver locking strategy
> > > > is something we want to refactor and having lock debugging during that
> > > > transition may be a life safer.
> > >
> > > cat /proc/sys/kernel/tainted
> >
> > Please note that Documentation/sysctl/kernel.txt is missing the explanation for
> > two bits in the value printed:
> >
> > 2048 - The system is working around a severe firmware bug.
> > 4096 - An out-of-tree module has been loaded.
> >
> > On my system, bit 4096 is set due to loading the VirtualBox module, which
> > disables lock debugging lock debugging. I suspect that loading VMware would
> > cause the same condition.
>
> Hmm. I wish OOT didn't disable lockdep, we do a lot of development with
> modules OOT because the turnaround is faster/easier (for not so
> experienced developers). Worst case we can patch it out of the base
> kernel I guess...

Me too. Now I understand John's patch entitled "[RFC] modpost: add option to 
allow external modules to avoid taint". I doubt that it will be allowed 
upstream, but I think that I will add it as a local commit.

I had failed to notice that the VB module was disabling lock checking, and I 
ACKed a patch to rtlwifi that triggers a nested lock WARNING. Oh well, at least 
the bug was not released into the wild yet.

Larry
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/