pagewalk: use lockdep_assert_held for locking validation

Use lockdep to check for held locks instead of using home grown asserts.

Link: https://lore.kernel.org/r/20190828141955.22210-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

mm/pagewalk.c

@@ -317,7 +317,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 	if (!walk.mm)
 		return -EINVAL;
 
-	VM_BUG_ON_MM(!rwsem_is_locked(&walk.mm->mmap_sem), walk.mm);
+	lockdep_assert_held(&walk.mm->mmap_sem);
 
 	vma = find_vma(walk.mm, start);
 	do {
@@ -367,7 +367,7 @@ int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 	if (!walk.mm)
 		return -EINVAL;
 
-	VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
+	lockdep_assert_held(&walk.mm->mmap_sem);
 
 	err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
 	if (err > 0)