BUG: spinlock recursion (sys_chdir, user_path_at, do_path_lookup ...)

[Peter Zijlstra]

> On Wed, 2011-01-12 at 23:52 +0100, Thomas Gleixner wrote:

> > @peterz: Why does lockdep ignore the lock recursion in that
> >          spin_lock_nested() call?

So after some hints on IRC on where to look:

<tglx>         spin_lock(&parent->d_lock);
<tglx>         spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
<tglx> if parent == dentry

That won't yell because you explicitly tell lockdep its ok, I know what
I'm doing.

Several lockdep annotations (including this one) allow you to annotate
real bugs away, hence you really need to be sure about things when you
make them.