5 files changed, 28 insertions, 21 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 29f4b790751c..a1b18c03b4c0 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -980,12 +980,9 @@ 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 70ca1852a0e5..0181b7b2281a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -61,6 +61,7 @@
 #include <linux/proc_fs.h>
 #include <linux/blkdev.h>
 #include <trace/sched.h>
+#include <linux/magic.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -212,6 +213,8 @@ 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);
@@ -237,6 +240,8 @@ 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/panic.c b/kernel/panic.c
index 2a2ff36ff44d..33cab3de1763 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -74,6 +74,9 @@ NORET_TYPE void panic(const char * fmt, ...)
         vsnprintf(buf, sizeof(buf), fmt, args);
         va_end(args);
         printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+        dump_stack();
+#endif
         bust_spinlocks(0);
 
         /*
@@ -355,15 +358,22 @@ EXPORT_SYMBOL(warn_slowpath);
 #endif
 
 #ifdef CONFIG_CC_STACKPROTECTOR
+
+#ifndef GCC_HAS_SP
+#warning You have selected the CONFIG_CC_STACKPROTECTOR option, but the gcc used does not support this.
+#endif
+
 /*
  * Called when gcc's -fstack-protector feature is used, and
  * gcc detects corruption of the on-stack canary value
  */
 void __stack_chk_fail(void)
 {
-        panic("stack-protector: Kernel stack is corrupted");
+        panic("stack-protector: Kernel stack is corrupted in: %p\n",
+                __builtin_return_address(0));
 }
 EXPORT_SYMBOL(__stack_chk_fail);
+
 #endif
 
 core_param(panic, panic_timeout, int, 0644);
diff --git a/kernel/sched.c b/kernel/sched.c
index 40d70d9c0af3..8db1a4cf2082 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6009,12 +6009,7 @@ 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));
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2f445833ae37..1f0c509b40d3 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -971,6 +971,8 @@ undo:
 }
 
 #ifdef CONFIG_SMP
+static struct workqueue_struct *work_on_cpu_wq __read_mostly;
+
 struct work_for_cpu {
         struct work_struct work;
         long (*fn)(void *);
@@ -991,8 +993,8 @@ static void do_work_for_cpu(struct work_struct *w)
  * @fn: the function to run
  * @arg: the function arg
  *
- * This will return -EINVAL in the cpu is not online, or the return value
- * of @fn otherwise.
+ * This will return the value @fn returns.
+ * It is up to the caller to ensure that the cpu doesn't go offline.
  */
 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 {
@@ -1001,14 +1003,8 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
         INIT_WORK(&wfc.work, do_work_for_cpu);
         wfc.fn = fn;
         wfc.arg = arg;
-        get_online_cpus();
-        if (unlikely(!cpu_online(cpu)))
-                wfc.ret = -EINVAL;
-        else {
-                schedule_work_on(cpu, &wfc.work);
-                flush_work(&wfc.work);
-        }
-        put_online_cpus();
+        queue_work_on(cpu, work_on_cpu_wq, &wfc.work);
+        flush_work(&wfc.work);
 
         return wfc.ret;
 }
@@ -1025,4 +1021,8 @@ void __init init_workqueues(void)
         hotcpu_notifier(workqueue_cpu_callback, 0);
         keventd_wq = create_workqueue("events");
         BUG_ON(!keventd_wq);
+#ifdef CONFIG_SMP
+        work_on_cpu_wq = create_workqueue("work_on_cpu");
+        BUG_ON(!work_on_cpu_wq);
+#endif
 }