Re: [PATCH v5.5 10/10] mmap locking API: rename mmap_sem to mmap_lock

[Jason Gunthorpe]

On Tue, May 19, 2020 at 07:39:30PM -0700, Michel Lespinasse wrote:
> > > I think this assertion should be deleted from this driver.  It's there
> > > in case get_user_pages_fast() takes the mmap sem.  It would make sense to
> > > have this assertion in get_user_pages_fast() in case we take the fast path
> > > which doesn't acquire the mmap_sem.  Something like this:
> 
> I like this idea a lot - having might_lock assertions in
> get_user_pages_fast makes a log more sense than doing the same at the
> call sites.

+1 I've wanted to see more complete lockdep annotations in gup.c for a
while now.. There has been a number of bugs this would have caught

Jason