linux-kernel - [PATCH] RDMA/umem: updated bug fix in error handling path

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Date:   Tue,  5 Mar 2019 18:00:22 -0800
From:   john.hubbard@...il.com
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Artemy Kovalyov <artemyko@...lanox.com>,
        Leon Romanovsky <leon@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Doug Ledford <dledford@...hat.com>, linux-rdma@...r.kernel.org
Subject: [PATCH] RDMA/umem: updated bug fix in error handling path

From: John Hubbard <jhubbard@...dia.com>

The previous attempted bug fix overlooked the fact that
ib_umem_odp_map_dma_single_page() was doing a put_page()
upon hitting an error. So there was not really a bug there.

Therefore, this reverts the off-by-one change, but
keeps the change to use release_pages() in the error path.

Fixes: commit xxxxxxxxxxxx ("RDMA/umem: minor bug fix in error handling path")
Suggested-by: Artemy Kovalyov <artemyko@...lanox.com>

Cc: Leon Romanovsky <leon@...nel.org>
Cc: Ira Weiny <ira.weiny@...el.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Doug Ledford <dledford@...hat.com>
Cc: linux-rdma@...r.kernel.org
Cc: linux-mm@...ck.org
Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
 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 d45735b02e07..c9cafaa080e7 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -686,10 +686,13 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
 
 		if (ret < 0) {
 			/*
-			 * Release pages, starting at the the first page
-			 * that experienced an error.
+			 * Release pages, remembering that the first page
+			 * to hit an error was already released by
+			 * ib_umem_odp_map_dma_single_page().
 			 */
-			release_pages(&local_page_list[j], npages - j);
+			if (npages - (j + 1) > 0)
+				release_pages(&local_page_list[j+1],
+					      npages - (j + 1));
 			break;
 		}
 	}
-- 
2.21.0