Disable CLONE_PARENT for init When global or container-init processes use CLONE_PARENT, they create a multi-rooted process tree. Besides, if the siblings of init exit, the SIGCHLD is not sent to init process resulting in the zombies sticking around indefinitely. So disable CLONE_PARENT for init. Lightly tested, RFC patch :-) Changelog[v2]: - Simplify patch description based on comments from Eric Biederman and Oleg Nesterov. - [Oleg Nesterov] Use SIGNAL_UNKILLABLE instead of is_global_init() Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx> Acked-by: Roland McGrath <roland@xxxxxxxxxx> --- kernel/fork.c | 11 +++++++++++ 1 file changed, 11 insertions(+) Index: linux-mmotm/kernel/fork.c =================================================================== --- linux-mmotm.orig/kernel/fork.c 2009-06-30 23:01:06.000000000 -0700 +++ linux-mmotm/kernel/fork.c 2009-06-30 23:13:53.000000000 -0700 @@ -974,6 +974,17 @@ static struct task_struct *copy_process( if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) return ERR_PTR(-EINVAL); + /* + * Swapper process sets the handler for SIGCHLD to SIG_DFL. If init + * creates a sibling and the sibling exits, the SIGCHLD is sent to + * the swapper (since the swapper's handler for SIGCHLD is SIG_DFL). + * But since the swapper does not reap its children, the zombie will + * remain forever. So prevent init from using CLONE_PARENT. + */ + if ((clone_flags & CLONE_PARENT) && + current->signal->flags & SIGNAL_UNKILLABLE) + return ERR_PTR(-EINVAL); + retval = security_task_create(clone_flags); if (retval) goto fork_out; _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
