From patchwork Fri Sep 2 18:27:46 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 1122892 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 p82IUd39015275 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL) for ; Fri, 2 Sep 2011 18:30:59 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 p82IT4gY010599; Fri, 2 Sep 2011 11:29:04 -0700 Received: from mail-gw0-f47.google.com (mail-gw0-f47.google.com [74.125.83.47]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p82IS9M0010022 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=FAIL); Fri, 2 Sep 2011 11:28:11 -0700 Received: by gwb11 with SMTP id 11so1768999gwb.6 for ; Fri, 02 Sep 2011 11:28:09 -0700 (PDT) Received: by 10.68.199.100 with SMTP id jj4mr2548290pbc.270.1314988088903; Fri, 02 Sep 2011 11:28:08 -0700 (PDT) Received: from localhost.localdomain ([121.167.223.83]) by mx.google.com with ESMTPS id i1sm11753361pbe.1.2011.09.02.11.28.05 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 02 Sep 2011 11:28:08 -0700 (PDT) From: Tejun Heo To: oleg@redhat.com, matthltc@us.ibm.com, rjw@sisk.pl, paul@paulmenage.org 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> Received-SPF: pass (localhost is always allowed.) X-Spam-Status: No, hits=-4.156 required=5 tests=AWL, BAYES_00, OSDL_HEADER_SUBJECT_BRACKETED X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf-20110901g X-Scanned-By: MIMEDefang 2.63 on 140.211.169.21 X-Scanned-By: MIMEDefang 2.63 on 140.211.169.51 Cc: Tejun Heo , containers@lists.linux-foundation.org, linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [linux-pm] [PATCH 2/6] freezer: set PF_NOFREEZE on a dying task right before TASK_DEAD setting bug in freezer_change_state() 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: , MIME-Version: 1.0 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]); Fri, 02 Sep 2011 18:30:59 +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 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();