The patch titled
uml: add stack usage monitoring
has been added to the -mm tree. Its filename is
uml-add-stack-usage-monitoring.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: uml: add stack usage monitoring
From: Jeff Dike <jdike@xxxxxxxxxxx>
Add a mechanism to see how much of a kernel stack is used. This allocates
zeroed stacks and sees where the lowest non-zero byte is on process exit. It
keeps track of the lowest value and logs values as they get lower.
Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/Kconfig.debug | 9 +++++++++
arch/um/defconfig | 1 +
arch/um/kernel/process.c | 29 +++++++++++++++++++++++++++++
include/asm-um/thread_info.h | 16 ++++++++++++++++
4 files changed, 55 insertions(+)
diff -puN arch/um/Kconfig.debug~uml-add-stack-usage-monitoring arch/um/Kconfig.debug
--- a/arch/um/Kconfig.debug~uml-add-stack-usage-monitoring
+++ a/arch/um/Kconfig.debug
@@ -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
diff -puN arch/um/defconfig~uml-add-stack-usage-monitoring arch/um/defconfig
--- a/arch/um/defconfig~uml-add-stack-usage-monitoring
+++ a/arch/um/defconfig
@@ -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
diff -puN arch/um/kernel/process.c~uml-add-stack-usage-monitoring arch/um/kernel/process.c
--- a/arch/um/kernel/process.c~uml-add-stack-usage-monitoring
+++ a/arch/um/kernel/process.c
@@ -427,3 +427,32 @@ unsigned long arch_align_stack(unsigned
return sp & ~0xf;
}
#endif
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+
+static DEFINE_SPINLOCK(low_water_lock);
+static int lowest_to_date = THREAD_SIZE;
+
+void check_stack_usage(struct thread_info *s)
+{
+ unsigned int *stack, *p, *end;
+ int left;
+
+ stack = (unsigned int *) (s + 1);
+ end = (unsigned int *) ((unsigned long) s + THREAD_SIZE);
+ for(p = stack; p < end; p++){
+ if(*p != 0)
+ break;
+ }
+
+ left = (p - stack) * sizeof(*p);
+
+ spin_lock(&low_water_lock);
+ if(left < lowest_to_date){
+ printk("Greatest stack depth - %d bytes left\n", left);
+ lowest_to_date = left;
+ }
+ spin_unlock(&low_water_lock);
+}
+
+#endif
diff -puN include/asm-um/thread_info.h~uml-add-stack-usage-monitoring include/asm-um/thread_info.h
--- a/include/asm-um/thread_info.h~uml-add-stack-usage-monitoring
+++ a/include/asm-um/thread_info.h
@@ -52,6 +52,20 @@ static inline struct thread_info *curren
return ti;
}
+#ifdef CONFIG_DEBUG_STACK_USAGE
+
+extern void check_stack_usage(struct thread_info *stack);
+
+#define alloc_thread_info(tsk) \
+ ((struct thread_info *) __get_free_pages(GFP_KERNEL | __GFP_ZERO, \
+ CONFIG_KERNEL_STACK_ORDER))
+
+#define free_thread_info(ti) ({ check_stack_usage(ti) ; \
+ free_pages((unsigned long)(ti), \
+ CONFIG_KERNEL_STACK_ORDER); })
+
+#else
+
/* thread information allocation */
#define alloc_thread_info(tsk) \
((struct thread_info *) __get_free_pages(GFP_KERNEL, \
@@ -61,6 +75,8 @@ static inline struct thread_info *curren
#endif
+#endif
+
#define PREEMPT_ACTIVE 0x10000000
#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
_
Patches currently in -mm which might be from jdike@xxxxxxxxxxx are
hostfs-convert-to-new-aops.patch
uml-fix-request-sector-update.patch
uml-use-get_free_pages-to-allocate-kernel-stacks.patch
uml-add-stack-usage-monitoring.patch
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