On Fri, 27 Jun 2014 08:58:57 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Thu, Jun 26, 2014 at 02:20:04PM -0400, Jeff Layton wrote: > > While testing some knfsd patches on XFS today, I got this lockdep > > splatter. The kernel is a stock -rc2 kernel with a pile of knfsd > > patches on top. There are a couple of others in other areas, but > > nothing that would affect this. > > > > Nothing crashed or seems to be hung, so I'm not sure if it's a real > > problem or not... > > Known false positive. the problem is that lockdep is too stupid to > realise you can't mmap a directory inode, but it sees unused > directory inodes from memory reclaim in page faults (i.e. under the > mmap_sem) and so therefore thinks that taking a page fault in > readdir() while holding a directory inode lock on a referenced > directory inode will deadlock.... > > Teaching lockdep the intricacies of locking heirarchies is difficult > and painful. Fixing this one (and all the other stupidities lockdep > reports because of this) can't be done through annotations - it > requires rewriting a bunch of directory code to use different locks. > And, well, it ain't actually broken right now and there's other more > important issues to be fixed, so unless someone else beats me to > rewriting the readdir readahead code, lockdep is going to remain > unhappy about XFS. > > Cheers, > > Dave. No problem. Just figured I'd report it in case it were something new. I'll just keep ignoring it. Thanks! -- Jeff Layton <jlayton@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
