On Thu, Mar 21, 2013 at 5:08 PM, Al Viro <v...@zeniv.linux.org.uk> wrote: > > Not really. Do that and yes, this deadlock goes away. But the locking > order in general goes to hell - we order directory inodes by "which dentry > is an ancestor of another?" So we have no warranty that we won't get > alias1/foo/bar/baz < alias2/foo. Take rename_lock() on those two and > have it race with rmdir alias2/foo/bar/baz (locks alias2/foo/bar, then > alias2/foo/bar/baz) and rmdir alias2/foo/bar (locks alias2/foo and > alias2/foo/bar). Oops - we have a cycle now...
Hmm. But again, that can't actually happen here. We're in /proc. You can't move the entries around. Also, we only changed the locking order for the "inode is identical" case where we take only *one* lock, we didn't change it for the cases where we take multiple locks (and order them topologically). So I agree that we need to avoid aliased directories in the *general* case. I'm just arguing that for the specific case of /proc, we should be ok. No? Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/