RDMA: Convert put_page() to put_user_page*()

For infiniband code that retains pages via get_user_pages*(), release
those pages via the new put_user_page(), or put_user_pages*(), instead of
put_page()

This is a tiny part of the second step of fixing the problem described in
[1]. The steps are:

1) Provide put_user_page*() routines, intended to be used for releasing
   pages that were pinned via get_user_pages*().

2) Convert all of the call sites for get_user_pages*(), to invoke
   put_user_page*(), instead of put_page(). This involves dozens of call
   sites, and will take some time.

3) After (2) is complete, use get_user_pages*() and put_user_page*() to
   implement tracking of these pages. This tracking will be separate from
   the existing struct page refcounting.

4) Use the tracking and identification of these pages, to implement
   special handling (especially in writeback paths) when the pages are
   backed by a filesystem. Again, [1] provides details as to why that is
   desirable.

[1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()"

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Jason Gunthorpe <jgg@mellanox.com>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

2 files changed, 9 insertions, 8 deletions

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 7edc5839606b..54628ef879f0 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -54,9 +54,10 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
 
 	for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
 		page = sg_page_iter_page(&sg_iter);
-		if (!PageDirty(page) && umem->writable && dirty)
-			set_page_dirty_lock(page);
-		put_page(page);
+		if (umem->writable && dirty)
+			put_user_pages_dirty_lock(&page, 1);
+		else
+			put_user_page(page);
 	}
 
 	sg_free_table(&umem->sg_head);
diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index c3b3c523401f..9001cc10770a 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -482,7 +482,7 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
  * The function returns -EFAULT if the DMA mapping operation fails. It returns
  * -EAGAIN if a concurrent invalidation prevents us from updating the page.
  *
- * The page is released via put_page even if the operation failed. For
+ * The page is released via put_user_page even if the operation failed. For
  * on-demand pinning, the page is released whenever it isn't stored in the
  * umem.
  */
@@ -530,7 +530,7 @@ static int ib_umem_odp_map_dma_single_page(
 	}
 
 out:
-	put_page(page);
+	put_user_page(page);
 
 	if (remove_existing_mapping) {
 		ib_umem_notifier_start_account(umem_odp);
@@ -653,7 +653,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
 					ret = -EFAULT;
 					break;
 				}
-				put_page(local_page_list[j]);
+				put_user_page(local_page_list[j]);
 				continue;
 			}
 
@@ -680,8 +680,8 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
 			 * ib_umem_odp_map_dma_single_page().
 			 */
 			if (npages - (j + 1) > 0)
-				release_pages(&local_page_list[j+1],
-					      npages - (j + 1));
+				put_user_pages(&local_page_list[j+1],
+					       npages - (j + 1));
 			break;
 		}
 	}