On 04/10, Eric W. Biederman wrote: > > Oleg Nesterov <[EMAIL PROTECTED]> writes: > > > 1. rename reparent_to_init() to reparent_kthread() and export it > > > > 2. use init_pid_ns.child_reaper instead of child_reaper(current) > > > > 3. set ->exit_signal = -1, so init can't see us and we don't use > > it to reap the task. > > > > 4. add reparent_kthread() to kthread() and stopmachine() > > > > If the goal is to hide from /sbin/init. We don't need to touch > kernel/kthread.c or > kernel/stop_machine.c > > Their parents are already kernel threads. > > For the kernel thread they all inherit signals with SIGCHLD set to > SIG_IGN, so there is child auto reaping in that form. Adding > the ->exit_signal = -1 would be a bonus but is not required.
Unless a kernel thread does kernel_thread() (not kthread_create) and exits. In that case the child will be re-parented to init which doesn't ignore SIGCHLD. Robin Holt wrote: > > wait_task_zombie() is taking many seconds to get through the list. > For the case of a modprobe, stop_machine creates one thread per cpu > (remember big number). All are parented to init and their exit will > cause wait_task_zombie to scan multiple times most of the way through > this very long list looking for threads which need to be reaped. initially, "stopmachine" threads were not parented to init. However, I agree, your patch is better, and solves most problems in more simple way. Including the above problem, I believe. "stopmachine" likely does exit_notify() and notices SIG_IGN (inherited from kthreadd_setup()) before "do_stop" does forget_original_parent(). Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
