1 files changed, 12 insertions, 4 deletions

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 283a76a9cc40..11ccfb0a63e7 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -17,6 +17,7 @@
 #include <asm/idle.h>
 #include <asm/mce.h>
 #include <asm/hw_irq.h>
+#include <asm/desc.h>
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/irq_vectors.h>
@@ -334,10 +335,17 @@ int check_irq_vectors_for_cpu_disable(void)
         for_each_online_cpu(cpu) {
                 if (cpu == this_cpu)
                         continue;
-                for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS;
-                     vector++) {
-                        if (per_cpu(vector_irq, cpu)[vector] < 0)
-                                count++;
+                /*
+                 * We scan from FIRST_EXTERNAL_VECTOR to first system
+                 * vector. If the vector is marked in the used vectors
+                 * bitmap or an irq is assigned to it, we don't count
+                 * it as available.
+                 */
+                for (vector = FIRST_EXTERNAL_VECTOR;
+                     vector < first_system_vector; vector++) {
+                        if (!test_bit(vector, used_vectors) &&
+                            per_cpu(vector_irq, cpu)[vector] < 0)
+                                        count++;
                 }
         }