2 files changed, 38 insertions, 19 deletions

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 50076d4366c4..2d65cfa5e0b4 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -89,16 +89,32 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
         task = task ? : current;
 
         if (in_task_stack(stack, task, info))
-                return 0;
+                goto recursion_check;
 
         if (task != current)
                 goto unknown;
 
         if (in_hardirq_stack(stack, info))
-                return 0;
+                goto recursion_check;
 
         if (in_softirq_stack(stack, info))
-                return 0;
+                goto recursion_check;
+
+        goto unknown;
+
+recursion_check:
+        /*
+         * Make sure we don't iterate through any given stack more than once.
+         * If it comes up a second time then there's something wrong going on:
+         * just break out and report an unknown stack type.
+         */
+        if (visit_mask) {
+                if (*visit_mask & (1UL << info->type))
+                        goto unknown;
+                *visit_mask |= 1UL << info->type;
+        }
+
+        return 0;
 
 unknown:
         info->type = STACK_TYPE_UNKNOWN;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 2e708afe146d..8cb6004a4dfd 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -47,8 +47,7 @@ void stack_type_str(enum stack_type type, const char **begin, const char **end)
         }
 }
 
-static bool in_exception_stack(unsigned long *stack, struct stack_info *info,
-                               unsigned long *visit_mask)
+static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
 {
         unsigned long *begin, *end;
         struct pt_regs *regs;
@@ -64,16 +63,6 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info,
                 if (stack < begin || stack >= end)
                         continue;
 
-                /*
-                 * Make sure we don't iterate through an exception stack more
-                 * than once.  If it comes up a second time then there's
-                 * something wrong going on - just break out and report an
-                 * unknown stack type.
-                 */
-                if (*visit_mask & (1U << k))
-                        break;
-                *visit_mask |= 1U << k;
-
                 info->type      = STACK_TYPE_EXCEPTION + k;
                 info->begin     = begin;
                 info->end       = end;
@@ -119,16 +108,30 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
         task = task ? : current;
 
         if (in_task_stack(stack, task, info))
-                return 0;
+                goto recursion_check;
 
         if (task != current)
                 goto unknown;
 
-        if (in_exception_stack(stack, info, visit_mask))
-                return 0;
+        if (in_exception_stack(stack, info))
+                goto recursion_check;
 
         if (in_irq_stack(stack, info))
-                return 0;
+                goto recursion_check;
+
+        goto unknown;
+
+recursion_check:
+        /*
+         * Make sure we don't iterate through any given stack more than once.
+         * If it comes up a second time then there's something wrong going on:
+         * just break out and report an unknown stack type.
+         */
+        if (visit_mask) {
+                if (*visit_mask & (1UL << info->type))
+                        goto unknown;
+                *visit_mask |= 1UL << info->type;
+        }
 
         return 0;