From patchwork Mon Aug 29 14:05:09 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 1108242 Received: from smtp1.linux-foundation.org (smtp1.linux-foundation.org [140.211.169.13]) by demeter2.kernel.org (8.14.4/8.14.4) with ESMTP id p7TEAkgW007756 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL) for ; Mon, 29 Aug 2011 14:11:06 GMT Received: from daredevil.linux-foundation.org (localhost [127.0.0.1]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p7TE8Wsa015450; Mon, 29 Aug 2011 07:08:32 -0700 Received: from mail-fx0-f47.google.com (mail-fx0-f47.google.com [209.85.161.47]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p7TE4Rq1015073 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=FAIL); Mon, 29 Aug 2011 07:05:16 -0700 Received: by mail-fx0-f47.google.com with SMTP id 11so4605036fxg.6 for ; Mon, 29 Aug 2011 07:05:15 -0700 (PDT) Received: by 10.223.29.9 with SMTP id o9mr7084190fac.131.1314626715721; Mon, 29 Aug 2011 07:05:15 -0700 (PDT) Received: from mtj.dyndns.org ([89.204.138.129]) by mx.google.com with ESMTPS id n7sm3788525faa.2.2011.08.29.07.05.13 (version=SSLv3 cipher=OTHER); Mon, 29 Aug 2011 07:05:14 -0700 (PDT) Date: Mon, 29 Aug 2011 16:05:09 +0200 From: Tejun Heo To: "Rafael J. Wysocki" , Oleg Nesterov , Paul Menage Message-ID: <20110829140509.GC18871@mtj.dyndns.org> References: <20110829140418.GB18871@mtj.dyndns.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20110829140418.GB18871@mtj.dyndns.org> User-Agent: Mutt/1.5.21 (2010-09-15) Received-SPF: pass (localhost is always allowed.) X-Spam-Status: No, hits=-4.31 required=5 tests=AWL, BAYES_00, OSDL_HEADER_SPF_PASS, OSDL_HEADER_SUBJECT_BRACKETED X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.21 Cc: containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [linux-pm] [PATCH pm-freezer 2/4] freezer: set PF_NOFREEZE on a dying task right before TASK_DEAD X-BeenThere: linux-pm@lists.linux-foundation.org X-Mailman-Version: 2.1.9 Precedence: list List-Id: Linux power management List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Mon, 29 Aug 2011 14:11:06 +0000 (UTC) 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 file changed, 4 insertions(+), 6 deletions(-) Index: work/kernel/exit.c =================================================================== --- work.orig/kernel/exit.c +++ work/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();