Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932129Ab0DPP3i (ORCPT ); Fri, 16 Apr 2010 11:29:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35690 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751710Ab0DPP3g (ORCPT ); Fri, 16 Apr 2010 11:29:36 -0400 Date: Fri, 16 Apr 2010 17:29:05 +0200 (CEST) From: John Kacur X-X-Sender: jkacur@localhost.localdomain To: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra cc: linux-rt-users@vger.kernel.org, Thomas Gleixner , Clark Williams , "Luis Claudio R. Goncalves" , Andrew Morton Subject: Re: [RFC: PATCH v2] lockdep: Make MAX_STACK_TRACE_ENTRIES configurable. In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8442 Lines: 229 On Fri, 16 Apr 2010, John Kacur wrote: > > This patch was created against v2.6.33.2-rt13 but is also intended for > mainline. > > Certain debug configurations tend to go over the MAX_STACK_TRACE_ENTRIES > limit without there really being any problem. > > This patch keeps the old default, but allows the user to configure a > higher value if desired. > > I tend to bump this value up for real-time debug configurations for > example. This is preferrable to indiscriminately turning off the locking > correctness validator. > > There have been some attempts to increase the default value in the past, > that were met with resistance by some, because of the legitimate concern > that this was growing too large and that we need to understand why. By > making it configurable, I hope to satisfy both sets of people - those who > believe they need to set it larger under special circumstances, and those > who want a reasonably small default. > > From 57479e7620d312353f5f5b173742e011896a9c74 Mon Sep 17 00:00:00 2001 > From: John Kacur > Date: Fri, 16 Apr 2010 13:24:02 +0200 > Subject: [RFC: PATCH] lockdep: Make MAX_STACK_TRACE_ENTRIES configurable. > > Certain configurations that have LOCKDEP turned on, run into the limit > where the MAX_STACK_TRACE_ENTRIES are too small. Rather than simply > turning of the locking correctness validator let the user configure this > value to something reasonable for their system. > > Signed-off-by: John Kacur > --- > kernel/lockdep.c | 8 ++++---- > kernel/lockdep_internals.h | 6 ------ > lib/Kconfig.debug | 9 +++++++++ > 3 files changed, 13 insertions(+), 10 deletions(-) > > diff --git a/kernel/lockdep.c b/kernel/lockdep.c > index 1199bda..6030521 100644 > --- a/kernel/lockdep.c > +++ b/kernel/lockdep.c > @@ -368,12 +368,12 @@ static int verbose(struct lock_class *class) > * addresses. Protected by the graph_lock. > */ > unsigned long nr_stack_trace_entries; > -static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; > +static unsigned long stack_trace[CONFIG_MAX_STACK_TRACE_ENTRIES]; > > static int save_trace(struct stack_trace *trace) > { > trace->nr_entries = 0; > - trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > + trace->max_entries = CONFIG_MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; > trace->entries = stack_trace + nr_stack_trace_entries; > > trace->skip = 3; > @@ -395,11 +395,11 @@ static int save_trace(struct stack_trace *trace) > > nr_stack_trace_entries += trace->nr_entries; > > - if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { > + if (nr_stack_trace_entries >= CONFIG_MAX_STACK_TRACE_ENTRIES-1) { > if (!debug_locks_off_graph_unlock()) > return 0; > > - printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); > + printk("BUG: CONFIG_MAX_STACK_TRACE_ENTRIES = %d too low!\n", CONFIG_MAX_STACK_TRACE_ENTRIES); > printk("turning off the locking correctness validator.\n"); > dump_stack(); > > diff --git a/kernel/lockdep_internals.h b/kernel/lockdep_internals.h > index a2ee95a..6887711 100644 > --- a/kernel/lockdep_internals.h > +++ b/kernel/lockdep_internals.h > @@ -61,12 +61,6 @@ enum { > > #define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5) > > -/* > - * Stack-trace: tightly packed array of stack backtrace > - * addresses. Protected by the hash_lock. > - */ > -#define MAX_STACK_TRACE_ENTRIES 262144UL > - > extern struct list_head all_lock_classes; > extern struct lock_chain lock_chains[]; > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index cbf6e02..ad35402 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -509,6 +509,15 @@ config LOCKDEP > select KALLSYMS > select KALLSYMS_ALL > > +config MAX_STACK_TRACE_ENTRIES > + int "MAX_STACK_TRACE_ENTRIES for LOCKDEP" > + depends on LOCKDEP > + default 262144 > + help > + This option allows you to change the default MAX_STACK_TRACE_ENTRIES > + used for LOCKDEP. Warning, increasing this number will increase the > + size of the stack_trace array, and thus the kernel size too. > + > config LOCK_STAT > bool "Lock usage statistics" > depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT > -- > 1.6.6.1 > > I missed the MAX_STACK_TRACE_ENTRIES in kernel/lockdep_proc.c This corrects that. >From 66b4fa66afefb9e22047ddc5a68c9886e1a59cf6 Mon Sep 17 00:00:00 2001 From: John Kacur Date: Fri, 16 Apr 2010 13:24:02 +0200 Subject: [PATCH] lockdep: Make MAX_STACK_TRACE_ENTRIES configurable. Certain configurations that have LOCKDEP turned on, run into the limit where the MAX_STACK_TRACE_ENTRIES are too small. Rather than simply turning of the locking correctness validator let the user configure this value to something reasonable for their system. Signed-off-by: John Kacur --- kernel/lockdep.c | 8 ++++---- kernel/lockdep_internals.h | 6 ------ kernel/lockdep_proc.c | 2 +- lib/Kconfig.debug | 9 +++++++++ 4 files changed, 14 insertions(+), 11 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 1199bda..6030521 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -368,12 +368,12 @@ static int verbose(struct lock_class *class) * addresses. Protected by the graph_lock. */ unsigned long nr_stack_trace_entries; -static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; +static unsigned long stack_trace[CONFIG_MAX_STACK_TRACE_ENTRIES]; static int save_trace(struct stack_trace *trace) { trace->nr_entries = 0; - trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; + trace->max_entries = CONFIG_MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; trace->entries = stack_trace + nr_stack_trace_entries; trace->skip = 3; @@ -395,11 +395,11 @@ static int save_trace(struct stack_trace *trace) nr_stack_trace_entries += trace->nr_entries; - if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { + if (nr_stack_trace_entries >= CONFIG_MAX_STACK_TRACE_ENTRIES-1) { if (!debug_locks_off_graph_unlock()) return 0; - printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n"); + printk("BUG: CONFIG_MAX_STACK_TRACE_ENTRIES = %d too low!\n", CONFIG_MAX_STACK_TRACE_ENTRIES); printk("turning off the locking correctness validator.\n"); dump_stack(); diff --git a/kernel/lockdep_internals.h b/kernel/lockdep_internals.h index a2ee95a..6887711 100644 --- a/kernel/lockdep_internals.h +++ b/kernel/lockdep_internals.h @@ -61,12 +61,6 @@ enum { #define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5) -/* - * Stack-trace: tightly packed array of stack backtrace - * addresses. Protected by the hash_lock. - */ -#define MAX_STACK_TRACE_ENTRIES 262144UL - extern struct list_head all_lock_classes; extern struct lock_chain lock_chains[]; diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c index d4aba4f..97fcb31 100644 --- a/kernel/lockdep_proc.c +++ b/kernel/lockdep_proc.c @@ -306,7 +306,7 @@ static int lockdep_stats_show(struct seq_file *m, void *v) seq_printf(m, " in-process chains: %11u\n", nr_process_chains); seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n", - nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES); + nr_stack_trace_entries, CONFIG_MAX_STACK_TRACE_ENTRIES); seq_printf(m, " combined max dependencies: %11u\n", (nr_hardirq_chains + 1) * (nr_softirq_chains + 1) * diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index cbf6e02..ad35402 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -509,6 +509,15 @@ config LOCKDEP select KALLSYMS select KALLSYMS_ALL +config MAX_STACK_TRACE_ENTRIES + int "MAX_STACK_TRACE_ENTRIES for LOCKDEP" + depends on LOCKDEP + default 262144 + help + This option allows you to change the default MAX_STACK_TRACE_ENTRIES + used for LOCKDEP. Warning, increasing this number will increase the + size of the stack_trace array, and thus the kernel size too. + config LOCK_STAT bool "Lock usage statistics" depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT -- 1.6.6.1 -- 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/