[PATCH v3 hmm 07/12] mm/hmm: Use lockdep instead of comments

From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jerome Glisse <jglisse@redhat.com>,
	Ralph Campbell <rcampbell@nvidia.com>,
	John Hubbard <jhubbard@nvidia.com>,
	Felix.Kuehling@amd.com
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Philip Yang <Philip.Yang@amd.com>,
	linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org,
	Souptick Joarder <jrdr.linux@gmail.com>,
	linux-mm@kvack.org, Jason Gunthorpe <jgg@mellanox.com>,
	dri-devel@lists.freedesktop.org, Ben Skeggs <bskeggs@redhat.com>
Subject: [PATCH v3 hmm 07/12] mm/hmm: Use lockdep instead of comments
Date: Thu, 13 Jun 2019 21:44:45 -0300	[thread overview]
Message-ID: <20190614004450.20252-8-jgg@ziepe.ca> (raw)
In-Reply-To: <20190614004450.20252-1-jgg@ziepe.ca>

From: Jason Gunthorpe <jgg@mellanox.com>

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>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
v2
- Fix missing & in lockdeps (Jason)
---
 mm/hmm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index 58712d74edd585..c0f622f86223c2 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -253,11 +253,11 @@ 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;
-- 
2.21.0

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