+ /*
+ * We must test the size in words, not in bits, because
+ * otherwise incoming sizes in the range -63..-1 will not run
+ * any scasq instructions, and then the flags used by the je
+ * instruction will have whatever random value was in place
+ * before. Nobody should call us like that, but
+ * find_next_zero_bit() does when offset and size are at the
+ * same word and it fails to find a zero itself.
+ */
+ size += 63;
+ size >>= 6;