The patch titled Subject: pidns: find_new_reaper() can no longer switch to init_pid_ns.child_reaper has been removed from the -mm tree. Its filename was pidns-find_new_reaper-can-no-longer-switch-to-init_pid_nschild_reaper.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: pidns: find_new_reaper() can no longer switch to init_pid_ns.child_reaper find_new_reaper() changes pid_ns->child_reaper, see add0d4df ("pid_ns: zap_pid_ns_processes: fix the ->child_reaper changing"). The original reason has gone away after the previous patch, ->children list must be empty after zap_pid_ns_processes(). However now we can not switch to init_pid_ns.child_reaper. __unhash_process() relies on the "->child_reaper == parent" check, but this check does not work if the last exiting task is also the child reaper. As Eric sugested, we can change __unhash_process() to use the parent's pid_ns and remove this code. Also, with this change we can move detach_pid(PIDTYPE_PID) back, where it was before the previous fix. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Louis Rilling <louis.rilling@xxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Acked-by: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Tested-by: Andrew Wagin <avagin@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/exit.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff -puN kernel/exit.c~pidns-find_new_reaper-can-no-longer-switch-to-init_pid_nschild_reaper kernel/exit.c --- a/kernel/exit.c~pidns-find_new_reaper-can-no-longer-switch-to-init_pid_nschild_reaper +++ a/kernel/exit.c @@ -64,6 +64,7 @@ static void exit_mm(struct task_struct * static void __unhash_process(struct task_struct *p, bool group_dead) { nr_threads--; + detach_pid(p, PIDTYPE_PID); if (group_dead) { detach_pid(p, PIDTYPE_PGID); detach_pid(p, PIDTYPE_SID); @@ -78,13 +79,12 @@ static void __unhash_process(struct task if (IS_ENABLED(CONFIG_PID_NS)) { struct task_struct *parent = p->real_parent; - if ((task_active_pid_ns(p)->child_reaper == parent) && + if ((task_active_pid_ns(parent)->child_reaper == parent) && list_empty(&parent->children) && (parent->flags & PF_EXITING)) wake_up_process(parent); } } - detach_pid(p, PIDTYPE_PID); list_del_rcu(&p->thread_group); } @@ -732,12 +732,6 @@ static struct task_struct *find_new_reap zap_pid_ns_processes(pid_ns); write_lock_irq(&tasklist_lock); - /* - * We can not clear ->child_reaper or leave it alone. - * There may by stealth EXIT_DEAD tasks on ->children, - * forget_original_parent() must move them somewhere. - */ - pid_ns->child_reaper = init_pid_ns.child_reaper; } else if (father->signal->has_child_subreaper) { struct task_struct *reaper; _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch linux-next.patch c-r-prctl-less-paranoid-prctl_set_mm_exe_file.patch mm-oom-do-not-schedule-if-current-has-been-killed.patch kmod-avoid-deadlock-from-recursive-kmod-call.patch c-r-fcntl-add-f_getowner_uids-option.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html