Potential NULL pointer deference in mm/memcontrol.c

[Yizhuo Zhai]

Hi All:
mm/memcontrol.c:
The function mem_cgroup_from_css() could return NULL, but some callers
in this file
checks the return value but directly dereference it, which seems
potentially unsafe.
Such callers include mem_cgroup_hierarchy_read(),
mem_cgroup_hierarchy_write(), mem_cgroup_read_u64(),
mem_cgroup_reset(), etc.
-- 
Kind Regards,

Yizhuo Zhai

Computer Science, Graduate Student
University of California, Riverside