On Fri, Nov 29, 2013 at 02:41:21AM +0000, Al Viro wrote: > On Thu, Nov 28, 2013 at 06:07:27PM -0800, Linus Torvalds wrote: > > > HOWEVER. It's certainly *not* valid if "current->fs->root/pwd" points > > to it. So yeah, there must have been an extra dput() somewhere. Or, > > more likely, I think, we don't get the refcount to some dentry > > properly any more. > > > > I don't see where, though. You did change where "LOOKUP_RCU" is > > cleared in unlazy_walk() but you did add that > > > > nd->path.dentry = NULL; > > > > and that looks like it should be ok. And I don't see what else would care. > > *nod* > > BTW, vfsmount refcount is 12, so we *definitely* nowhere near the > final mntput(), etc. and mnt->mnt_root itself should also have > contributed. > > I'm going to try to find out _which_ test buggers the refcount - at > least that way I'll have something resembling a usable reproducer... OK, we have a winner. generic/234 drops refcount of root dentry by about 20 (and yes, I should've started with that one, what with Ted's report). Run it several times (4 should suffice nicely) and the damn thing triggers right there. Uff... At least that takes under a minute instead of a couple of hours, which makes debugging that shite much more tolerable... -- 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
