From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755836Ab2JPEgL (ORCPT ); Tue, 16 Oct 2012 00:36:11 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:44651 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755794Ab2JPEgI (ORCPT ); Tue, 16 Oct 2012 00:36:08 -0400 Date: Mon, 15 Oct 2012 21:35:59 -0700 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: cernekee@gmail.com, torbenh@gmx.de, torvalds@linux-foundation.org, tglx@linutronix.de, srivatsa.bhat@linux.vnet.ibm.com Subject: Re: [PATCH] Fix scheduling-while-atomic problem in console_cpu_notify() Message-ID: <20121016043559.GA32179@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20121016003128.GA5879@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121016003128.GA5879@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12101604-5518-0000-0000-000008784164 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 15, 2012 at 05:31:28PM -0700, Paul E. McKenney wrote: > The console_cpu_notify( function runs with interrupts disabled in > the CPU_DEAD case. It therefore cannot block, for example, as will > happen when it calls console_lock(). Therefore, remove the CPU_DEAD > leg of the switch statement to avoid this problem. > > Signed-off-by: Paul E. McKenney s/CPU_DEAD/CPU_DYING/ Apparently it is a bad idea to compose and send a patch while in a C++ standards committee meeting where people are arguing about async futures... Fixed patch below. Thanx, Paul ------------------------------------------------------------------------ printk: Fix scheduling-while-atomic problem in console_cpu_notify() The console_cpu_notify( function runs with interrupts disabled in the CPU_DYING case. It therefore cannot block, for example, as will happen when it calls console_lock(). Therefore, remove the CPU_DYING leg of the switch statement to avoid this problem. Signed-off-by: Paul E. McKenney diff --git a/kernel/printk.c b/kernel/printk.c index 66a2ea3..2d607f4 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1890,7 +1890,6 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self, switch (action) { case CPU_ONLINE: case CPU_DEAD: - case CPU_DYING: case CPU_DOWN_FAILED: case CPU_UP_CANCELED: console_lock();