On Tue, Dec 12, 2017 at 08:03:43AM -0500, Theodore Ts'o wrote:

On Tue, Dec 12, 2017 at 02:20:32PM +0900, Byungchul Park wrote:

quoted

The *problem* is false positives, since locks and waiters in
kernel are not classified properly, at the moment, which is just
a fact that is not related to cross-release stuff at all. IOW,
that would be useful once all locks and waiters are classified
correctly. It might take time but the classifying is a must-do
we have to keep doing.

This is the wrong attitude.  The reason why LOCKDEP was so powerful
was because it automatically classified locks, instead of requiring
developers to document the locking hierarchy.  Requiring developers to
have to document and classified locks --- especially when the d*mned
mechanisms for doign so are so primitive and not even documented ---
is a complete non-strarter.

That's not fair.  We had to annotate i_mutex nesting, for example, and
several other places.  crosslock doesn't change anything in this respect,
it's just that the case that you hit every damn day as a filesystem
developer is something that the normal person almost never does.

So are you willing to take my patch?  Or give me permission to keep in
the ext4 tree?

He sent a patch earlier ...