SUNRPC: Set memalloc_nofs_save() for sync tasks

[ Upstream commit f0940f4 ]

We could recurse into NFS doing memory reclaim while sending a sync task,
which might result in a deadlock.  Set memalloc_nofs_save for sync task
execution.

Fixes: a1231fd ("SUNRPC: Set memalloc_nofs_save() on all rpciod/xprtiod jobs")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/sunrpc/sched.c

@@ -963,8 +963,11 @@ void rpc_execute(struct rpc_task *task)
 
 	rpc_set_active(task);
 	rpc_make_runnable(rpciod_workqueue, task);
-	if (!is_async)
+	if (!is_async) {
+		unsigned int pflags = memalloc_nofs_save();
 		__rpc_execute(task);
+		memalloc_nofs_restore(pflags);
+	}
 }
 
 static void rpc_async_schedule(struct work_struct *work)