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From:   john.hubbard@gmail.com
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Subject: [PATCH 10/34] genwqe: convert put_page() to put_user_page*()
Date:   Thu,  1 Aug 2019 19:19:41 -0700
Message-Id: <20190802022005.5117-11-jhubbard@nvidia.com>
In-Reply-To: <20190802022005.5117-1-jhubbard@nvidia.com>
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From: John Hubbard <jhubbard@nvidia.com>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

This changes the release code slightly, because each page slot in the
page_list[] array is no longer checked for NULL. However, that check
was wrong anyway, because the get_user_pages() pattern of usage here
never allowed for NULL entries within a range of pinned pages.

Cc: Frank Haverkamp <haver@linux.vnet.ibm.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/misc/genwqe/card_utils.c | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
index 2e1c4d2905e8..2a888f31d2c5 100644
--- a/drivers/misc/genwqe/card_utils.c
+++ b/drivers/misc/genwqe/card_utils.c
@@ -517,24 +517,13 @@ int genwqe_free_sync_sgl(struct genwqe_dev *cd, struct genwqe_sgl *sgl)
 /**
  * genwqe_free_user_pages() - Give pinned pages back
  *
- * Documentation of get_user_pages is in mm/gup.c:
- *
- * If the page is written to, set_page_dirty (or set_page_dirty_lock,
- * as appropriate) must be called after the page is finished with, and
- * before put_page is called.
+ * The pages may have been written to, so we call put_user_pages_dirty_lock(),
+ * rather than put_user_pages().
  */
 static int genwqe_free_user_pages(struct page **page_list,
 			unsigned int nr_pages, int dirty)
 {
-	unsigned int i;
-
-	for (i = 0; i < nr_pages; i++) {
-		if (page_list[i] != NULL) {
-			if (dirty)
-				set_page_dirty_lock(page_list[i]);
-			put_page(page_list[i]);
-		}
-	}
+	put_user_pages_dirty_lock(page_list, nr_pages, dirty);
 	return 0;
 }
 
-- 
2.22.0