cgroup_enable_task_cg_lists && PF_EXITING (Was: KCSAN: data-race in exit_signals / prepare_signal)

[Oleg Nesterov]

could you explain the usage of siglock/PF_EXITING in
cgroup_enable_task_cg_lists() ?

PF_EXITING is protected by cgroup_threadgroup_rwsem, not by
sighand->siglock.

Oleg.