1 files changed, 22 insertions, 0 deletions

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 8565d944f7c..38868adf07e 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -90,6 +90,27 @@ static void do_test(unsigned long size)
         iounmap(p);
 }
 
+/*
+ * Tests how mmiotrace behaves in face of multiple ioremap / iounmaps in
+ * a short time. We had a bug in deferred freeing procedure which tried
+ * to free this region multiple times (ioremap can reuse the same address
+ * for many mappings).
+ */
+static void do_test_bulk_ioremapping(void)
+{
+        void __iomem *p;
+        int i;
+
+        for (i = 0; i < 10; ++i) {
+                p = ioremap_nocache(mmio_address, PAGE_SIZE);
+                if (p)
+                        iounmap(p);
+        }
+
+        /* Force freeing. If it will crash we will know why. */
+        synchronize_rcu();
+}
+
 static int __init init(void)
 {
         unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
@@ -104,6 +125,7 @@ static int __init init(void)
                    "and writing 16 kB of rubbish in there.\n",
                    size >> 10, mmio_address);
         do_test(size);
+        do_test_bulk_ioremapping();
         pr_info("All done.\n");
         return 0;
 }