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Message-ID: <20070620182312.GA7856@c2.user-mode-linux.org>
Date: Wed, 20 Jun 2007 14:23:12 -0400
From: Jeff Dike <jdike@...toit.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
uml-devel <user-mode-linux-devel@...ts.sourceforge.net>
Subject: Re: [PATCH 2/2] UML - Add stack usage monitoring
On Tue, Jun 19, 2007 at 01:14:41PM -0700, Andrew Morton wrote:
> Oh well. Your new code should really be generic, utilising the
> stack-page-zeroing which CONFIG_DEBUG_STACK_USAGE enables. There's nothing
> UML-specific about it.
>
> low_water_lock and lowest_to_date should be static to check_stack_usage(),
> btw..
OK, here's a fixed version. Dunno if the prink wants to be more elaborate.
If this is OK, then drop the UML version.
Jeff
--
Work email - jdike at linux dot intel dot com
Add generic exit-time stack-depth checking to CONFIG_DEBUG_STACK_USAGE.
This also adds UML support.
Tested on UML and i386.
Signed-off-by: Jeff Dike <jdike@...ux.intel.com>
--
arch/um/Kconfig.debug | 9 +++++++++
arch/um/defconfig | 1 +
include/asm-um/thread_info.h | 9 +++++++++
kernel/exit.c | 24 ++++++++++++++++++++++++
4 files changed, 43 insertions(+)
Index: linux-2.6.21-mm/kernel/exit.c
===================================================================
--- linux-2.6.21-mm.orig/kernel/exit.c 2007-06-20 11:57:07.000000000 -0400
+++ linux-2.6.21-mm/kernel/exit.c 2007-06-20 13:53:20.000000000 -0400
@@ -867,6 +867,27 @@ static void exit_notify(struct task_stru
release_task(tsk);
}
+#ifdef CONFIG_DEBUG_STACK_USAGE
+static void check_stack_usage(void)
+{
+ static DEFINE_SPINLOCK(low_water_lock);
+ static int lowest_to_date = THREAD_SIZE;
+ unsigned long *n = end_of_stack(current), free;
+
+ while (*n == 0)
+ n++;
+ free = (unsigned long)n - (unsigned long)end_of_stack(current);
+
+ spin_lock(&low_water_lock);
+ if (free < lowest_to_date) {
+ printk(KERN_WARNING "Greatest stack depth - %ld bytes left\n",
+ free);
+ lowest_to_date = free;
+ }
+ spin_unlock(&low_water_lock);
+}
+#endif
+
fastcall NORET_TYPE void do_exit(long code)
{
struct task_struct *tsk = current;
@@ -942,6 +963,9 @@ fastcall NORET_TYPE void do_exit(long co
exit_sem(tsk);
__exit_files(tsk);
__exit_fs(tsk);
+#ifdef CONFIG_DEBUG_STACK_USAGE
+ check_stack_usage();
+#endif
exit_thread();
container_exit(tsk, 1);
exit_keys(tsk);
Index: linux-2.6.21-mm/arch/um/Kconfig.debug
===================================================================
--- linux-2.6.21-mm.orig/arch/um/Kconfig.debug 2007-06-20 11:57:13.000000000 -0400
+++ linux-2.6.21-mm/arch/um/Kconfig.debug 2007-06-20 11:59:43.000000000 -0400
@@ -47,4 +47,13 @@ config GCOV
If you're involved in UML kernel development and want to use gcov,
say Y. If you're unsure, say N.
+config DEBUG_STACK_USAGE
+ bool "Stack utilization instrumentation"
+ default N
+ help
+ Track the maximum kernel stack usage - this will look at each
+ kernel stack at process exit and log it if it's the deepest
+ stack seen so far.
+
+ This option will slow down process creation and destruction somewhat.
endmenu
Index: linux-2.6.21-mm/arch/um/defconfig
===================================================================
--- linux-2.6.21-mm.orig/arch/um/defconfig 2007-06-20 11:57:13.000000000 -0400
+++ linux-2.6.21-mm/arch/um/defconfig 2007-06-20 11:58:29.000000000 -0400
@@ -527,3 +527,4 @@ CONFIG_FORCED_INLINING=y
# CONFIG_RCU_TORTURE_TEST is not set
# CONFIG_GPROF is not set
# CONFIG_GCOV is not set
+# CONFIG_DEBUG_STACK_USAGE is not set
Index: linux-2.6.21-mm/include/asm-um/thread_info.h
===================================================================
--- linux-2.6.21-mm.orig/include/asm-um/thread_info.h 2007-06-20 11:57:13.000000000 -0400
+++ linux-2.6.21-mm/include/asm-um/thread_info.h 2007-06-20 14:17:22.000000000 -0400
@@ -52,10 +52,19 @@ static inline struct thread_info *curren
return ti;
}
+#ifdef CONFIG_DEBUG_STACK_USAGE
+
+#define alloc_thread_info(tsk) \
+ ((struct thread_info *) __get_free_pages(GFP_KERNEL | __GFP_ZERO, \
+ CONFIG_KERNEL_STACK_ORDER))
+#else
+
/* thread information allocation */
#define alloc_thread_info(tsk) \
((struct thread_info *) __get_free_pages(GFP_KERNEL, \
CONFIG_KERNEL_STACK_ORDER))
+#endif
+
#define free_thread_info(ti) \
free_pages((unsigned long)(ti),CONFIG_KERNEL_STACK_ORDER)
-
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