Re: [PATCH v2 2/3] lockdep: Remove BROKEN flag of LOCKDEP_CROSSRELEASE

From: Bart Van Assche
Date: Thu Oct 19 2017 - 16:41:30 EST


On Thu, 2017-10-19 at 13:33 -0700, Matthew Wilcox wrote:
> For example, the page lock is not annotatable with lockdep -- we return
> to userspace with it held, for heaven's sake! So it is quite easy for
> someone not familiar with the MM locking hierarchy to inadvertently
> introduce an ABBA deadlock against the page lock. (ie me. I did that.)
> Right now, that has to be caught by a human reviewer; if cross-release
> checking can catch that, then it's worth having.

Hello Matthew,

Although I agree that enabling lock inversion checking for page locks is
useful, I think my questions still apply to other locking objects than page
locks.

Thanks,

Bart.