It's pretty unusual to have an int as a private data field and it
makes it impossible to carray a pointer value through it.  Let's make
it an unsigned long.  AFAICS, this shouldn't break anything.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>