[PATCH] net_dma: fix memory leak in dma_pin_iocvec_pages

[Roman Gushchin <klamm@yandex-team.ru>]

dma_pin_iovec_pages() calls get_user_pages() for each iovec. If
get_user_pages() returns a number smaller than the requested number,
dma_pin_iovec_pages() calls dma_unpin_iovec_pages(). It releases
previously allocated iovecs, but pages pinned by last get_user_pages()
call remain unreleased.
Fix this by calling put_page() for each such page.

Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
---
 drivers/dma/iovlock.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/iovlock.c b/drivers/dma/iovlock.c
index bb48a57..c393cf9 100644
--- a/drivers/dma/iovlock.c
+++ b/drivers/dma/iovlock.c
@@ -107,8 +107,11 @@ struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)
 			NULL);
 		up_read(&current->mm->mmap_sem);
 
-		if (ret != page_list->nr_pages)
+		if (ret != page_list->nr_pages) {
+			for (i = 0; i < ret; i++)
+				put_page(page_list->pages[i]);
 			goto unpin;
+		}
 
 		local_list->nr_iovecs = i + 1;
 	}
-- 
1.9.3