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Date: Tue, 24 Apr 2012 14:54:02 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] spinlock_debug: Print kallsyms name for lock
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On Mon, 23 Apr 2012 20:17:03 -0700
Stephen Boyd <sboyd@codeaurora.org> wrote:

> On 04/23/12 14:54, Andrew Morton wrote:
> >
> >> --- a/lib/spinlock_debug.c
> >> +++ b/lib/spinlock_debug.c
> >> @@ -58,7 +58,7 @@ static void spin_dump(raw_spinlock_t *lock, const char *msg)
> >>  	printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
> >>  		msg, raw_smp_processor_id(),
> >>  		current->comm, task_pid_nr(current));
> >> -	printk(KERN_EMERG " lock: %p, .magic: %08x, .owner: %s/%d, "
> >> +	printk(KERN_EMERG " lock: %ps, .magic: %08x, .owner: %s/%d, "
> >>  			".owner_cpu: %d\n",
> >>  		lock, lock->magic,
> >>  		owner ? owner->comm : "<none>",
> > Maybe.  It will only do useful things for statically-allocated locks
> > which are rare and which we are unlikely to screw up as easily as locks
> > which lie in dynamically allocated memory.
> 
> Agreed. It catches the really stupid stuff and that's about it. I was
> thinking we could get more information about dynamic allocated locks by
> adding some code to slab to find the slab that a pointer is allocated
> in. Does that sound possible?

Well lockdep knows lots of things about the lock, including numerous
stack backtraces which can be used to identify the lock.  Making 
spinlock_debug use lockdep infrastructure seems a good fit.