Re: [Proposal] DEBUG_SLAB should select DEBUG_SPINLOCK

["Randy.Dunlap" <rddunlap@osdl.org>]

On 28 May 2004 12:45:35 -0700 Roland Dreier wrote:

| I recently had a rather amusing debugging session.  I developed some
| code that worked fine on my test kernel, which had CONFIG_DEBUG_SLAB
| turned on.  However, as soon as I moved to a kernel without slab
| debugging to do some benchmarks, I started getting lockups.  It turns
| out that I had a spinlock in my data structure that I forgot to
| initialize but the poisoning from slab debugging had taken care of
| initializing it for me.  I didn't catch this during development
| because I had left CONFIG_DEBUG_SPINLOCK off.
| 
| Fortunately (for my sanity) I was able to diagnose this pretty quickly
| with the help of the NMI oopser.  However, for other developers' sake,
| I think it might make sense to add
| 
| 	select DEBUG_SPINLOCK
| 
| to the DEBUG_SLAB stanza of Kconfig.
| 
| I'm not posting a patch because I wanted to find out the status of
| Randy Dunlap's patch that consolidates the debugging options.  Is that
| patch going to be merged, in someone's tree somewhere, dropped, or what?

Andrew asked me to delay it until 2.6.6, which I did.
Sent that, but not merged.

I will be rediffing it and resending it again for 2.6.7 and
probably some intermediate kernels if that's what it takes.

| If the consensus is that we don't want to do this anyway, that's
| fine.  I mostly wanted to share this bug, which amused me.



--
~Randy