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authorMichael Ellerman <mpe@ellerman.id.au>2014-05-28 18:21:18 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-06-06 13:55:04 +1000
commitd34b661b10ab49c9058cd6602fd0162ba6db40a3 (patch)
treec2cb021b5db8aeaec1ff1981e8abbce6bae72973
parent09567e7fd44291bfc08accfdd67ad8f467842332 (diff)
selftests/powerpc: Test the THP bug we fixed in the previous commit
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--tools/testing/selftests/powerpc/Makefile2
-rw-r--r--tools/testing/selftests/powerpc/mm/Makefile18
-rw-r--r--tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c72
3 files changed, 91 insertions, 1 deletions
diff --git a/tools/testing/selftests/powerpc/Makefile b/tools/testing/selftests/powerpc/Makefile
index 316194f26ff4..b3dbe9ef1a40 100644
--- a/tools/testing/selftests/powerpc/Makefile
+++ b/tools/testing/selftests/powerpc/Makefile
@@ -13,7 +13,7 @@ CFLAGS := -Wall -O2 -flto -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(CUR
export CC CFLAGS
-TARGETS = pmu copyloops
+TARGETS = pmu copyloops mm
endif
diff --git a/tools/testing/selftests/powerpc/mm/Makefile b/tools/testing/selftests/powerpc/mm/Makefile
new file mode 100644
index 000000000000..357ccbd6bad9
--- /dev/null
+++ b/tools/testing/selftests/powerpc/mm/Makefile
@@ -0,0 +1,18 @@
+noarg:
+ $(MAKE) -C ../
+
+PROGS := hugetlb_vs_thp_test
+
+all: $(PROGS)
+
+$(PROGS): ../harness.c
+
+run_tests: all
+ @-for PROG in $(PROGS); do \
+ ./$$PROG; \
+ done;
+
+clean:
+ rm -f $(PROGS)
+
+.PHONY: all run_tests clean
diff --git a/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c b/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
new file mode 100644
index 000000000000..3d8e5b033e1d
--- /dev/null
+++ b/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c
@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+/* This must match the huge page & THP size */
+#define SIZE (16 * 1024 * 1024)
+
+static int test_body(void)
+{
+ void *addr;
+ char *p;
+
+ addr = (void *)0xa0000000;
+
+ p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
+ MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ if (p != MAP_FAILED) {
+ /*
+ * Typically the mmap will fail because no huge pages are
+ * allocated on the system. But if there are huge pages
+ * allocated the mmap will succeed. That's fine too, we just
+ * munmap here before continuing.
+ */
+ munmap(addr, SIZE);
+ }
+
+ p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ if (p == MAP_FAILED) {
+ printf("Mapping failed @ %p\n", addr);
+ perror("mmap");
+ return 1;
+ }
+
+ /*
+ * Either a user or kernel access is sufficient to trigger the bug.
+ * A kernel access is easier to spot & debug, as it will trigger the
+ * softlockup or RCU stall detectors, and when the system is kicked
+ * into xmon we get a backtrace in the kernel.
+ *
+ * A good option is:
+ * getcwd(p, SIZE);
+ *
+ * For the purposes of this testcase it's preferable to spin in
+ * userspace, so the harness can kill us if we get stuck. That way we
+ * see a test failure rather than a dead system.
+ */
+ *p = 0xf;
+
+ munmap(addr, SIZE);
+
+ return 0;
+}
+
+static int test_main(void)
+{
+ int i;
+
+ /* 10,000 because it's a "bunch", and completes reasonably quickly */
+ for (i = 0; i < 10000; i++)
+ if (test_body())
+ return 1;
+
+ return 0;
+}
+
+int main(void)
+{
+ return test_harness(test_main, "hugetlb_vs_thp");
+}