Author: Julia Lawall <julia@diku.dk> request_region should be used with release_region, not request_mem_region. Geert Uytterhoeven pointed out that in the case of drivers/video/gbefb.c, the problem is actually the other way around; request_mem_region should be used instead of request_region. The semantic patch that finds/fixes this problem is as follows: (http://coccinelle.lip6.fr/) // @r1@ expression start; @@ request_region(start,…) @b1@ …