RDMA/i40w: Hold read semaphore while looking after VMA

VMA lookup is supposed to be performed while mmap_sem is held.

Fixes: f26c7c83395b ("i40iw: Add 2MB page support")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/i40iw/i40iw_verbs.c

@@ -1410,6 +1410,7 @@ static void i40iw_set_hugetlb_values(u64 addr, struct i40iw_mr *iwmr)
 	struct vm_area_struct *vma;
 	struct hstate *h;
 
+	down_read(&current->mm->mmap_sem);
 	vma = find_vma(current->mm, addr);
 	if (vma && is_vm_hugetlb_page(vma)) {
 		h = hstate_vma(vma);
@@ -1418,6 +1419,7 @@ static void i40iw_set_hugetlb_values(u64 addr, struct i40iw_mr *iwmr)
 			iwmr->page_msk = huge_page_mask(h);
 		}
 	}
+	up_read(&current->mm->mmap_sem);
 }
 
 /**