Re: lockdep annotations?

[Lachlan McIlroy <lachlan@xxxxxxx>]

David Chinner wrote:
> On Mon, Sep 03, 2007 at 12:46:30PM +1000, Lachlan McIlroy wrote:
> > This is a locking inversion between the iolock and iprune_mutex.  I
> > hadn't seen this one before.  Was your system running low on memory
> > at the time?
> >
> > We can't drop the iolock in the write path so we'll have to avoid
> > acquiring the iolock in xfs_ireclaim() which means we'll need another
> > way to synchronise with xfs_sync_inodes().
> I don't think a deadlock exists here - we have to be going through
> memory reclaim to hit this inversion, so the only place that we
> can deadlock is if we are holding the iprune_mutex across a memory
> allocation. I don't think we do that....
>
> Not to mention that the inode we hold the iolock on won't be on the
> inode free list so we won't ever try to lock it during reclaim, either.
Yep.  This is just another case where we've confused lockdep.