tree 926064bd7909f60daed3b6b963555e57cab7b520
parent 8382fcac1b813ad0a4e68a838fc7ae93fa39eda0
author Eric W. Biederman <ebiederm@xmission.com> 1356150432 -0800
committer Eric W. Biederman <ebiederm@xmission.com> 1356480605 -0800

pidns: Stop pid allocation when init dies

Oleg pointed out that in a pid namespace the sequence.
- pid 1 becomes a zombie
- setns(thepidns), fork,...
- reaping pid 1.
- The injected processes exiting.

Can lead to processes attempting access their child reaper and
instead following a stale pointer.

That waitpid for init can return before all of the processes in
the pid namespace have exited is also unfortunate.

Avoid these problems by disabling the allocation of new pids in a pid
namespace when init dies, instead of when the last process in a pid
namespace is reaped.

Pointed-out-by:  Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>