From befca96779b0259ac8fad0183e748a62935c39cb Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Thu, 18 Jun 2009 16:49:11 -0700 Subject: [PATCH] ptrace: wait_task_zombie: do not account traced sub-threads The bug is ancient. If we trace the sub-thread of our natural child and this sub-thread exits, we update parent->signal->cxxx fields. But we should not do this until the whole thread-group exits, otherwise we account this thread (and all other live threads) twice. Add the task_detached() check. No need to check thread_group_empty(), wait_consider_task()->delay_group_leader() already did this. Signed-off-by: Oleg Nesterov Cc: Peter Zijlstra Acked-by: Roland McGrath Cc: Stanislaw Gruszka Cc: Vitaly Mayatskikh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 13ae64001fe..628d41f0dd5 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1197,8 +1197,11 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) } traced = ptrace_reparented(p); - - if (likely(!traced)) { + /* + * It can be ptraced but not reparented, check + * !task_detached() to filter out sub-threads. + */ + if (likely(!traced) && likely(!task_detached(p))) { struct signal_struct *psig; struct signal_struct *sig;