xen-blkback: fix memory leak when persistent grants are used

Currently shrink_free_pagepool() is called before the pages used for
persistent grants are released via free_persistent_gnts(). This
results in a memory leak when a VBD that uses persistent grants is
torn down.

Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: "Roger Pau Monné" <[email protected]>
Cc: Ian Campbell <[email protected]>
Reviewed-by: David Vrabel <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Anthony Liguori <[email protected]>
Signed-off-by: Matt Rushton <[email protected]>
Signed-off-by: Matt Wilson <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 6620b73d0490..30ef7b390df5 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -625,9 +625,6 @@ purge_gnt_list:
 			print_stats(blkif);
 	}
 
-	/* Since we are shutting down remove all pages from the buffer */
-	shrink_free_pagepool(blkif, 0 /* All */);
-
 	/* Free all persistent grant pages */
 	if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
 		free_persistent_gnts(blkif, &blkif->persistent_gnts,
@@ -636,6 +633,9 @@ purge_gnt_list:
 	BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
 	blkif->persistent_gnt_c = 0;
 
+	/* Since we are shutting down remove all pages from the buffer */
+	shrink_free_pagepool(blkif, 0 /* All */);
+
 	if (log_stats)
 		print_stats(blkif);