I'm not totally grokking how sparse is put together yet, but I've got
this:

Some symbols with type SYM_NODE are getting ctype->base_type==NULL,
causing a segfault in type_difference:422.   (If I work around that one,
there's another spot at line 680.  I started to follow what was going on
a bit at that point and realized they were probably symptoms, not the
actual bug, so I stopped working around it.)

I've got a config against bk-current that will trigger this in
fs/cramfs/uncompress.c attached in case it helps any.

Oh, BTW, the way you have struct ctype_sym declared inside struct symbol
confuses the crap out of gdb, but gcc appears to like it, so... *shrug*.

Should this be cc:ed to linux-kernel, or do you have another place in
mind?

-- 

Ryan Anderson
  sometimes Pug Majere