From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935593AbZFOVbe (ORCPT ); Mon, 15 Jun 2009 17:31:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934385AbZFOVb0 (ORCPT ); Mon, 15 Jun 2009 17:31:26 -0400 Received: from mx2.redhat.com ([66.187.237.31]:44783 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756063AbZFOVb0 (ORCPT ); Mon, 15 Jun 2009 17:31:26 -0400 Date: Mon, 15 Jun 2009 23:26:48 +0200 From: Oleg Nesterov To: Andrew Morton Cc: Peter Zijlstra , Roland McGrath , Stanislaw Gruszka , Vitaly Mayatskikh , linux-kernel@vger.kernel.org Subject: [PATCH 1/2] ptrace: wait_task_zombie: do not account traced sub-threads Message-ID: <20090615212648.GA22751@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The bug is ancient, the fix doesn't depend on other changes in -mm. 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 --- PTRACE/kernel/exit.c~1_WAIT_REPARENTED 2009-06-15 21:04:49.000000000 +0200 +++ PTRACE/kernel/exit.c 2009-06-15 22:26:02.000000000 +0200 @@ -1189,7 +1189,7 @@ static int wait_task_zombie(struct wait_ traced = ptrace_reparented(p); - if (likely(!traced)) { + if (likely(!traced) && likely(!task_detached(p))) { struct signal_struct *psig; struct signal_struct *sig; struct task_cputime cputime;