3 files changed, 7 insertions, 10 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 8f6185e69b69..fb8de6cbf2c7 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -899,12 +899,9 @@ 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);
         unsigned long free;
 
-        while (*n == 0)
-                n++;
-        free = (unsigned long)n - (unsigned long)end_of_stack(current);
+        free = stack_not_used(current);
 
         if (free >= lowest_to_date)
                 return;
diff --git a/kernel/fork.c b/kernel/fork.c
index 19908b26cf80..d428336e7aa1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -54,6 +54,7 @@
 #include <linux/tty.h>
 #include <linux/proc_fs.h>
 #include <linux/blkdev.h>
+#include <linux/magic.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -186,6 +187,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 {
         struct task_struct *tsk;
         struct thread_info *ti;
+        unsigned long *stackend;
+
         int err;
 
         prepare_to_copy(orig);
@@ -211,6 +214,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
                 goto out;
 
         setup_thread_stack(tsk, orig);
+        stackend = end_of_stack(tsk);
+        *stackend = STACK_END_MAGIC;    /* for overflow detection */
 
 #ifdef CONFIG_CC_STACKPROTECTOR
         tsk->stack_canary = get_random_int();
diff --git a/kernel/sched.c b/kernel/sched.c
index cfa222a91539..a964ed945094 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5748,12 +5748,7 @@ void sched_show_task(struct task_struct *p)
                 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
 #endif
 #ifdef CONFIG_DEBUG_STACK_USAGE
-        {
-                unsigned long *n = end_of_stack(p);
-                while (!*n)
-                        n++;
-                free = (unsigned long)n - (unsigned long)end_of_stack(p);
-        }
+        free = stack_not_used(p);
 #endif
         printk(KERN_CONT "%5lu %5d %6d\n", free,
                 task_pid_nr(p), task_pid_nr(p->real_parent));