From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754374Ab1IBS2N (ORCPT ); Fri, 2 Sep 2011 14:28:13 -0400 Received: from mail-gw0-f46.google.com ([74.125.83.46]:48414 "EHLO mail-gw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754308Ab1IBS2K (ORCPT ); Fri, 2 Sep 2011 14:28:10 -0400 From: Tejun Heo To: oleg@redhat.com, matthltc@us.ibm.com, rjw@sisk.pl, paul@paulmenage.org Cc: containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 2/6] freezer: set PF_NOFREEZE on a dying task right before TASK_DEAD setting bug in freezer_change_state() Date: Sat, 3 Sep 2011 03:27:46 +0900 Message-Id: <1314988070-12244-3-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.6 In-Reply-To: <1314988070-12244-1-git-send-email-tj@kernel.org> References: <1314988070-12244-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3fb45733df "freezer: make exiting tasks properly unfreezable" removed clear_freeze_flag() from exit path and set PF_NOFREEZE right after PTRACE_EVENT_EXIT; however, Oleg pointed out that following exit paths may cause interaction with device drivers after PM freezer consider the system frozen. There's no try_to_freeze() call in the exit path and the only necessary guarantee is that freezer doesn't hang waiting for zombies. Set PF_NOFREEZE right before setting tsk->state to TASK_DEAD instead. Signed-off-by: Tejun Heo Reported-by: Oleg Nesterov Cc: "Rafael J. Wysocki" --- kernel/exit.c | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index ac58259..7b6c4fa 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -913,12 +913,6 @@ NORET_TYPE void do_exit(long code) ptrace_event(PTRACE_EVENT_EXIT, code); - /* - * With ptrace notification done, there's no point in freezing from - * here on. Disallow freezing. - */ - current->flags |= PF_NOFREEZE; - validate_creds_for_do_exit(tsk); /* @@ -1044,6 +1038,10 @@ NORET_TYPE void do_exit(long code) preempt_disable(); exit_rcu(); + + /* this task is now dead and freezer should ignore it */ + current->flags |= PF_NOFREEZE; + /* causes final put_task_struct in finish_task_switch(). */ tsk->state = TASK_DEAD; schedule(); -- 1.7.6