From: Jason Gunthorpe <jgg@mellanox.com>
Date: Thu, 23 May 2019 14:23:30 +0000 (-0300)
Subject: mm/hmm: Use lockdep instead of comments
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8a1a0cd0b770a0f40a49db923479879fa7135aae;p=linux.git

mm/hmm: Use lockdep instead of comments

So we can check locking at runtime.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---

diff --git a/mm/hmm.c b/mm/hmm.c
index 1eddda45cefae..6f5dc6d568feb 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -246,11 +246,11 @@ 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);
+
 	/* Sanity check */
 	if (!mm || !mirror || !mirror->ops)
 		return -EINVAL;