On Thu, May 23, 2019 at 9:05 PM Jason Gunthorpe <jgg@xxxxxxxx> wrote:
>
> From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
>
> So we can check locking at runtime.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> ---
> mm/hmm.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 2695925c0c5927..46872306f922bb 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -256,11 +256,11 @@ static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
> *
> * To start mirroring a process address space, the device driver must register
> * an HMM mirror struct.
> - *
> - * THE mm->mmap_sem MUST BE HELD IN WRITE MODE !
> */
> int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
> {
> + lockdep_assert_held_exclusive(mm->mmap_sem);
> +
Gentle query, does the same required in hmm_mirror_unregister() ?
> /* Sanity check */
> if (!mm || !mirror || !mirror->ops)
> return -EINVAL;
> --
> 2.21.0
>
