Commit 7528e95b authored May 31, 2019 by Tejun Heo Committed by Greg Kroah-Hartman Aug 09, 2019

cgroup: Call cgroup_release() before __exit_signal()



commit 6b115bf58e6f013ca75e7115aabcbd56c20ff31d upstream.

cgroup_release() calls cgroup_subsys->release() which is used by the
pids controller to uncharge its pid.  We want to use it to manage
iteration of dying tasks which requires putting it before
__unhash_process().  Move cgroup_release() above __exit_signal().
While this makes it uncharge before the pid is freed, pid is RCU freed
anyway and the window is very narrow.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e6e9bcef

kernel/exit.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -194,6 +194,7 @@ void release_task(struct task_struct *p)
		rcu_read_unlock();

		proc_flush_task(p);
		cgroup_release(p);

		write_lock_irq(&tasklist_lock);
		ptrace_release_task(p);
		@@ -219,7 +220,6 @@ void release_task(struct task_struct *p)
		}

		write_unlock_irq(&tasklist_lock);
		cgroup_release(p);
		release_thread(p);
		call_rcu(&p->rcu, delayed_put_task_struct);