Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759892AbYG3RS7 (ORCPT ); Wed, 30 Jul 2008 13:18:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753171AbYG3RSu (ORCPT ); Wed, 30 Jul 2008 13:18:50 -0400 Received: from e28smtp07.in.ibm.com ([59.145.155.7]:36067 "EHLO e28esmtp07.in.ibm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752322AbYG3RSs (ORCPT ); Wed, 30 Jul 2008 13:18:48 -0400 Date: Wed, 30 Jul 2008 22:48:42 +0530 From: Chirag Jog To: J?rgen Mell , Thomas Gleixner Cc: Thomas Gleixner , LKML , rt-users , Steven Rostedt , Clark Williams , Peter Zijlstra , Josh Triplett , "Timothy R. Chavez" Subject: [PATCH] Fix Bug messages Message-ID: <20080730171842.GB3420@linux.vnet.ibm.com> Reply-To: Chirag Jog Mail-Followup-To: J?rgen Mell , Thomas Gleixner , LKML , rt-users , Steven Rostedt , Clark Williams , Peter Zijlstra , Josh Triplett , "Timothy R. Chavez" References: <200807301101.32417.j.mell@t-online.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <200807301101.32417.j.mell@t-online.de> Organization: IBM LTC User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4778 Lines: 155 * J?rgen Mell [2008-07-30 11:01:32]: > Hello Thomas, > > On Wednesday, 30. July 2008, Thomas Gleixner wrote: > > We are pleased to announce the 2.6.26-rt1 tree, which can be > > downloaded from the location: > > I have tried the new kernel and have some good news and some bad news: > > The good news: The machine boots and seems to run without major problems. > > The bad news: It produces continuously lots of bug messages in the error > logs (cf. attached dmesg.tgz). The error at rtmutex.c:743 was already > present in 2.6.25-rt* when ACPI was enabled. The 'using smp_processor_id > () in preemptible code' is new here with 2.6.26. > > Machine is an old Athlon XP (single core) on an EPOX mainboard with VIA > chipset. > > If I can help with testing, please let me know. > > Bye, > J?rgen > > This patch should solve some of the bug messages. It does two things: 1. Change rt_runtime_lock to be a raw spinlock as the comment above it says: it is nested inside the rq lock. 2. Change mnt_writers to be a per_cpu locked variable. This eliminates the need for the codepath to disable preemption and then potentially sleep, leading to the BUG messages Signed-Off-By: Chirag Index: linux-2.6.26-rt1/kernel/sched.c =================================================================== --- linux-2.6.26-rt1.orig/kernel/sched.c 2008-07-30 22:37:19.000000000 +0530 +++ linux-2.6.26-rt1/kernel/sched.c 2008-07-30 22:37:24.000000000 +0530 @@ -208,7 +208,7 @@ struct rt_bandwidth { /* nests inside the rq lock: */ - spinlock_t rt_runtime_lock; + raw_spinlock_t rt_runtime_lock; ktime_t rt_period; u64 rt_runtime; struct hrtimer rt_period_timer; @@ -472,7 +472,7 @@ u64 rt_time; u64 rt_runtime; /* Nests inside the rq lock: */ - spinlock_t rt_runtime_lock; + raw_spinlock_t rt_runtime_lock; #ifdef CONFIG_RT_GROUP_SCHED unsigned long rt_nr_boosted; Index: linux-2.6.26-rt1/fs/namespace.c =================================================================== --- linux-2.6.26-rt1.orig/fs/namespace.c 2008-07-30 22:39:30.000000000 +0530 +++ linux-2.6.26-rt1/fs/namespace.c 2008-07-30 22:39:36.000000000 +0530 @@ -178,13 +178,13 @@ unsigned long count; struct vfsmount *mnt; } ____cacheline_aligned_in_smp; -static DEFINE_PER_CPU(struct mnt_writer, mnt_writers); +static DEFINE_PER_CPU_LOCKED(struct mnt_writer, mnt_writers); static int __init init_mnt_writers(void) { int cpu; for_each_possible_cpu(cpu) { - struct mnt_writer *writer = &per_cpu(mnt_writers, cpu); + struct mnt_writer *writer = &per_cpu_var_locked(mnt_writers, cpu); spin_lock_init(&writer->lock); lockdep_set_class(&writer->lock, &writer->lock_class); writer->count = 0; @@ -199,7 +199,7 @@ struct mnt_writer *cpu_writer; for_each_possible_cpu(cpu) { - cpu_writer = &per_cpu(mnt_writers, cpu); + cpu_writer = &per_cpu_var_locked(mnt_writers, cpu); spin_unlock(&cpu_writer->lock); } } @@ -251,8 +251,8 @@ { int ret = 0; struct mnt_writer *cpu_writer; - - cpu_writer = &get_cpu_var(mnt_writers); + int cpu = 0; + cpu_writer = &get_cpu_var_locked(mnt_writers, &cpu); spin_lock(&cpu_writer->lock); if (__mnt_is_readonly(mnt)) { ret = -EROFS; @@ -262,7 +262,7 @@ cpu_writer->count++; out: spin_unlock(&cpu_writer->lock); - put_cpu_var(mnt_writers); + put_cpu_var_locked(mnt_writers, cpu); return ret; } EXPORT_SYMBOL_GPL(mnt_want_write); @@ -273,7 +273,7 @@ struct mnt_writer *cpu_writer; for_each_possible_cpu(cpu) { - cpu_writer = &per_cpu(mnt_writers, cpu); + cpu_writer = &per_cpu_var_locked(mnt_writers, cpu); spin_lock(&cpu_writer->lock); __clear_mnt_count(cpu_writer); cpu_writer->mnt = NULL; @@ -332,8 +332,8 @@ { int must_check_underflow = 0; struct mnt_writer *cpu_writer; - - cpu_writer = &get_cpu_var(mnt_writers); + int cpu = 0; + cpu_writer = &get_cpu_var_locked(mnt_writers, &cpu); spin_lock(&cpu_writer->lock); use_cpu_writer_for_mount(cpu_writer, mnt); @@ -360,7 +360,7 @@ * __mnt_writers can underflow. Without it, * we could theoretically wrap __mnt_writers. */ - put_cpu_var(mnt_writers); + put_cpu_var_locked(mnt_writers, cpu); } EXPORT_SYMBOL_GPL(mnt_drop_write); @@ -612,7 +612,7 @@ * can come in. */ for_each_possible_cpu(cpu) { - struct mnt_writer *cpu_writer = &per_cpu(mnt_writers, cpu); + struct mnt_writer *cpu_writer = &per_cpu_var_locked(mnt_writers, cpu); if (cpu_writer->mnt != mnt) continue; spin_lock(&cpu_writer->lock); -- 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/