Re: [PATCH 4/4] mm/gup: Assert that the mmap lock is held in __get_user_pages()

Michel Lespinasse
2020-09-30T23:24:56Z

On Wed, Sep 30, 2020 at 5:32 AM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> On Tue, Sep 29, 2020 at 06:20:01PM -0700, Jann Horn wrote:
> > After having cleaned up all GUP callers (except for the atomisp staging
> > driver, which currently gets mmap locking completely wrong [1]) to always
> > ensure that they hold the mmap lock when calling into GUP (unless the mm is
> > not yet globally visible), add an assertion to make sure it stays that way
> > going forward.

Thanks for doing this, there is a lot of value in ensuring that a
function's callers follows the prerequisites.

Acked-by: Michel Lespinasse <walken@google.com>