-
Oleg Nesterov authored
If the new child migrates to another cgroup before cgroup_post_fork() calls subsys->fork(), then both pids_can_attach() and pids_fork() will do the same pids_uncharge(old_pids) + pids_charge(pids) sequence twice. Change copy_process() to call threadgroup_change_begin/threadgroup_change_end unconditionally. percpu_down_read() is cheap and this allows other cleanups, see the next changes. Also, this way we can unify cgroup_threadgroup_rwsem and dup_mmap_sem. Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Acked-by:
Zefan Li <lizefan@huawei.com> Signed-off-by:
Tejun Heo <tj@kernel.org>
c9e75f04