ftrace: Optimize the allocation for mcount entries

If we can't allocate this size, try something smaller with half of the
size. Its order should be decreased by one instead of divided by two.

Link: https://lkml.kernel.org/r/[email protected]

Cc: <[email protected]>
Cc: <[email protected]>
Cc: [email protected]
Fixes: a790087 ("ftrace: Allocate the mcount record pages as groups")
Signed-off-by: Wang Wensheng <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: Wang Wensheng

kernel/trace/ftrace.c

@@ -3190,7 +3190,7 @@ static int ftrace_allocate_records(struct ftrace_page *pg, int count)
 		/* if we can't allocate this size, try something smaller */
 		if (!order)
 			return -ENOMEM;
-		order >>= 1;
+		order--;
 		goto again;
 	}