misc/habana: Use FOLL_LONGTERM for userptr

These are persistent, not just for the duration of a dma operation.
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: Oded Gabbay <oded.gabbay@gmail.com>
Cc: Omer Shpigelman <oshpigelman@habana.ai>
Cc: Ofir Bitton <obitton@habana.ai>
Cc: Tomer Tayar <ttayar@habana.ai>
Cc: Moti Haimovski <mhaimovski@habana.ai>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Pawel Piskorski <ppiskorski@habana.ai>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-5-daniel.vetter@ffwll.ch

drivers/misc/habanalabs/common/memory.c

@@ -1435,7 +1435,8 @@ static int get_user_memory(struct hl_device *hdev, u64 addr, u64 size,
 	if (!userptr->pages)
 		return -ENOMEM;
 
-	rc = pin_user_pages_fast(start, npages, FOLL_FORCE | FOLL_WRITE,
+	rc = pin_user_pages_fast(start, npages,
+				 FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
 				 userptr->pages);
 
 	if (rc != npages) {