[PATCH v3] RDMA/umem: minor bug fix in error handling path

[john . hubbard]

From: John Hubbard <jhubbard@xxxxxxxxxx>

1. Bug fix: fix an off by one error in the code that
cleans up if it fails to dma-map a page, after having
done a get_user_pages_remote() on a range of pages.

2. Refinement: for that same cleanup code, release_pages()
is better than put_page() in a loop.

Cc: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Doug Ledford <dledford@xxxxxxxxxx>
Cc: linux-rdma@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
 drivers/infiniband/core/umem_odp.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index acb882f279cb..d45735b02e07 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -40,6 +40,7 @@
 #include <linux/vmalloc.h>
 #include <linux/hugetlb.h>
 #include <linux/interval_tree_generic.h>
+#include <linux/pagemap.h>
 
 #include <rdma/ib_verbs.h>
 #include <rdma/ib_umem.h>
@@ -684,9 +685,11 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
 		mutex_unlock(&umem_odp->umem_mutex);
 
 		if (ret < 0) {
-			/* Release left over pages when handling errors. */
-			for (++j; j < npages; ++j)
-				put_page(local_page_list[j]);
+			/*
+			 * Release pages, starting at the the first page
+			 * that experienced an error.
+			 */
+			release_pages(&local_page_list[j], npages - j);
 			break;
 		}
 	}
-- 
2.21.0