Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759129AbYCNAVL (ORCPT ); Thu, 13 Mar 2008 20:21:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751926AbYCNAU4 (ORCPT ); Thu, 13 Mar 2008 20:20:56 -0400 Received: from mga11.intel.com ([192.55.52.93]:12517 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751477AbYCNAUz (ORCPT ); Thu, 13 Mar 2008 20:20:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,497,1199692800"; d="scan'208";a="306082853" Date: Thu, 13 Mar 2008 17:18:19 -0700 From: Venki Pallipadi To: Len Brown Cc: "Rafael J. Wysocki" , Venki Pallipadi , Miklos Szeredi , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: ACPI lockdep warning on boot, 2.6.25-rc5 Message-ID: <20080314001819.GA32584@linux-os.sc.intel.com> References: <200803122301.17356.rjw@sisk.pl> <200803131614.33386.lenb@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200803131614.33386.lenb@kernel.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5307 Lines: 131 On Thu, Mar 13, 2008 at 04:14:32PM -0400, Len Brown wrote: > On Wednesday 12 March 2008, Rafael J. Wysocki wrote: > > On Wednesday, 12 of March 2008, Miklos Szeredi wrote: > > > I don't know whether this is a problem in reality or not, but it does > > > interfere with debugging the rest of the kernel, since this turns off > > > lockdep at boottime. > > > > Well, I think Venki should see it (CCed). > > > > Thanks, > > Rafael > > > > > > > [ 0.592488] ACPI: CPU0 (power states: C1[C1] C2[C2] C3[C3]) > > > [ 0.593038] ------------[ cut here ]------------ > > > [ 0.593267] WARNING: at kernel/lockdep.c:2035 trace_hardirqs_on+0xa0/0x115() > > > [ 0.593596] Modules linked in: > > > [ 0.593756] Pid: 0, comm: swapper Not tainted 2.6.25-rc5 #8 > > > [ 0.594017] > > > [ 0.594017] Call Trace: > > > [ 0.594216] [] warn_on_slowpath+0x58/0x6b > > > [ 0.594495] [] ? _spin_unlock_irqrestore+0x38/0x47 > > > [ 0.594809] [] ? acpi_os_release_lock+0x9/0xb > > > [ 0.595103] [] ? acpi_set_register+0x161/0x173 > > > [ 0.595401] [] ? acpi_processor_idle+0x1de/0x546 > > > [ 0.595706] [] ? default_idle+0x0/0x73 > > > [ 0.595970] [] trace_hardirqs_on+0xa0/0x115 > > > [ 0.596049] [] ? acpi_processor_idle+0x0/0x546 > > > [ 0.596346] [] acpi_processor_idle+0x1de/0x546 > > > [ 0.596642] [] ? default_idle+0x0/0x73 > > > [ 0.596912] [] ? acpi_processor_idle+0x0/0x546 > > > [ 0.597209] [] ? default_idle+0x0/0x73 > > > [ 0.597472] [] cpu_idle+0xa7/0xd1 > > > [ 0.597717] [] rest_init+0x55/0x57 > > > [ 0.597957] [] start_kernel+0x29d/0x2a8 > > > [ 0.598215] [] _sinittext+0x1da/0x1e1 > > > [ 0.598464] > > > [ 0.598546] ---[ end trace 778e504de7e3b1e3 ]--- > > Venki, > > this reproduces in my t61 using Miklos' config (though i had to increase > the logbuff to catch it) > > -Len Below patch should fix this warning. I would say warning is pretty harmless.. Thanks, Venki --- This avoids the harmless WARNING by lockdep in acpi_processor_idle(). The reason for WARNING is because at the depth of idle handling code, some of the idle handlers disable interrupts, some times, while returning from the idle handler. After return, acpi_processor_idle and few other routines in the file did an unconditional local_irq_enable(). With LOCKDEP, enabling irq when it is alread enabled generates the below WARNING. > > [ 0.593038] ------------[ cut here ]------------ > > [ 0.593267] WARNING: at kernel/lockdep.c:2035 trace_hardirqs_on+0xa0/0x115() > > [ 0.593596] Modules linked in: > > [ 0.593756] Pid: 0, comm: swapper Not tainted 2.6.25-rc5 #8 > > [ 0.594017] > > [ 0.594017] Call Trace: > > [ 0.594216] [] warn_on_slowpath+0x58/0x6b > > [ 0.594495] [] ? _spin_unlock_irqrestore+0x38/0x47 > > [ 0.594809] [] ? acpi_os_release_lock+0x9/0xb > > [ 0.595103] [] ? acpi_set_register+0x161/0x173 > > [ 0.595401] [] ? acpi_processor_idle+0x1de/0x546 > > [ 0.595706] [] ? default_idle+0x0/0x73 > > [ 0.595970] [] trace_hardirqs_on+0xa0/0x115 > > [ 0.596049] [] ? acpi_processor_idle+0x0/0x546 > > [ 0.596346] [] acpi_processor_idle+0x1de/0x546 > > [ 0.596642] [] ? default_idle+0x0/0x73 > > [ 0.596912] [] ? acpi_processor_idle+0x0/0x546 > > [ 0.597209] [] ? default_idle+0x0/0x73 > > [ 0.597472] [] cpu_idle+0xa7/0xd1 > > [ 0.597717] [] rest_init+0x55/0x57 > > [ 0.597957] [] start_kernel+0x29d/0x2a8 > > [ 0.598215] [] _sinittext+0x1da/0x1e1 > > [ 0.598464] > > [ 0.598546] ---[ end trace 778e504de7e3b1e3 ]--- Signed-off-by: Venkatesh Pallipadi Index: linux-2.6.git/drivers/acpi/processor_idle.c =================================================================== --- linux-2.6.git.orig/drivers/acpi/processor_idle.c 2008-03-12 05:17:12.000000000 -0700 +++ linux-2.6.git/drivers/acpi/processor_idle.c 2008-03-13 10:00:47.000000000 -0700 @@ -216,8 +216,10 @@ * test NEED_RESCHED: */ smp_mb(); - if (!need_resched()) + if (!need_resched()) { safe_halt(); + local_irq_disable(); + } current_thread_info()->status |= TS_POLLING; } @@ -421,7 +423,9 @@ else acpi_safe_halt(); - local_irq_enable(); + if (irqs_disabled()) + local_irq_enable(); + return; } @@ -530,7 +534,9 @@ * skew otherwise. */ sleep_ticks = 0xFFFFFFFF; - local_irq_enable(); + if (irqs_disabled()) + local_irq_enable(); + break; case ACPI_STATE_C2: -- 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/