Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755879AbaJ2SHj (ORCPT ); Wed, 29 Oct 2014 14:07:39 -0400 Received: from casper.infradead.org ([85.118.1.10]:45486 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755506AbaJ2SHh (ORCPT ); Wed, 29 Oct 2014 14:07:37 -0400 Date: Wed, 29 Oct 2014 19:07:34 +0100 From: Peter Zijlstra To: Sabrina Dubroca Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jeffrey.t.kirsher@intel.com, Thomas Gleixner Subject: Re: e1000_netpoll(): disable_irq() triggers might_sleep() on linux-next Message-ID: <20141029180734.GQ12706@worktop.programming.kicks-ass.net> References: <20141029155620.GA4886@kria> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141029155620.GA4886@kria> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 29, 2014 at 04:56:20PM +0100, Sabrina Dubroca wrote: > commit e22b886a8a43b ("sched/wait: Add might_sleep() checks") included > in today's linux-next added a check that fires on e1000 with netpoll: > > > BUG: sleeping function called from invalid context at kernel/irq/manage.c:104 > in_atomic(): 1, irqs_disabled(): 1, pid: 1, name: systemd > no locks held by systemd/1. > irq event stamp: 10102965 > hardirqs last enabled at (10102965): [] vprintk_emit+0x2dd/0x6a0 > hardirqs last disabled at (10102964): [] vprintk_emit+0x77/0x6a0 > softirqs last enabled at (10102342): [] __do_softirq+0x27a/0x6f0 > softirqs last disabled at (10102337): [] irq_exit+0x56/0xe0 > Preemption disabled at:[] printk_emit+0x31/0x33 > > CPU: 1 PID: 1 Comm: systemd Not tainted 3.18.0-rc2-next-20141029-dirty #222 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140617_173321-var-lib-archbuild-testing-x86_64-tobias 04/01/2014 > ffffffff81a82291 ffff88001e743978 ffffffff817df31d 0000000000000000 > 0000000000000000 ffff88001e7439a8 ffffffff8108dfa2 ffff88001e7439a8 > ffffffff81a82291 0000000000000068 0000000000000000 ffff88001e7439d8 > Call Trace: > [] dump_stack+0x4f/0x7c > [] ___might_sleep+0x182/0x2b0 > [] __might_sleep+0x3a/0xc0 > [] synchronize_irq+0x38/0xa0 > [] disable_irq+0x20/0x30 > [] e1000_netpoll+0x23/0x60 > [] netpoll_poll_dev+0x72/0x3a0 > [] netpoll_send_skb_on_dev+0x1b7/0x2e0 > [] netpoll_send_udp+0x2e3/0x490 Oh cute.. not entirely sure what to do there. This only works if you _know_ desc->threads_active will never be !0. The best I can come up with is something like this, which avoids the might_sleep() in the one special case. Thomas? --- kernel/irq/manage.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 0a9104b4608b..b7cb736a8b32 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -100,8 +100,11 @@ void synchronize_irq(unsigned int irq) * running. Now verify that no threaded handlers are * active. */ - wait_event(desc->wait_for_threads, - !atomic_read(&desc->threads_active)); + if (atomic_read(&desc->threads_active)) { + might_sleep(); + __wait_event(desc->wait_for_threads, + !atomic_read(&desc->threads_active)); + } } } EXPORT_SYMBOL(synchronize_irq); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/