arm64 does not support the soft-dirty PTE bit. However, the `soft-dirty`
test suite is currently run unconditionally and therefore generates
spurious test failures on arm64. There are also some tests in
`madv_populate` which assume it is supported.
For `soft-dirty` lets disable the whole suite for arm64; it is no longer
built and run_vmtests.sh will skip it if its not present.
For `madv_populate`, we need a runtime mechanism so that the remaining
tests continue to be run. Unfortunately, the only way to determine if
the soft-dirty dirty bit is supported is to write to a page, then see if
the bit is set in /proc/self/pagemap. But the tests that we want to
conditionally execute are testing precicesly this. So if we introduced
this feature check, we could accedentally turn a real failure (on a
system that claims to support soft-dirty) into a skip. So instead, do
the check based on architecture; for arm64, we report that soft-dirty is
not supported.
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
---
tools/testing/selftests/mm/Makefile | 5 ++++-
tools/testing/selftests/mm/madv_populate.c | 26 ++++++++++++++++++++--
tools/testing/selftests/mm/run_vmtests.sh | 5 ++++-
3 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 66d7c07dc177..3514697fc2db 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -63,12 +63,15 @@ TEST_GEN_PROGS += thuge-gen
TEST_GEN_PROGS += transhuge-stress
TEST_GEN_PROGS += uffd-stress
TEST_GEN_PROGS += uffd-unit-tests
-TEST_GEN_PROGS += soft-dirty
TEST_GEN_PROGS += split_huge_page_test
TEST_GEN_PROGS += ksm_tests
TEST_GEN_PROGS += ksm_functional_tests
TEST_GEN_PROGS += mdwe_test
+ifneq ($(ARCH),arm64)
+TEST_GEN_PROGS += soft-dirty
+endif
+
ifeq ($(ARCH),x86_64)
CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
CAN_BUILD_X86_64 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_64bit_program.c)
diff --git a/tools/testing/selftests/mm/madv_populate.c b/tools/testing/selftests/mm/madv_populate.c
index 60547245e479..17bcb07f19f3 100644
--- a/tools/testing/selftests/mm/madv_populate.c
+++ b/tools/testing/selftests/mm/madv_populate.c
@@ -264,14 +264,35 @@ static void test_softdirty(void)
munmap(addr, SIZE);
}
+static int system_has_softdirty(void)
+{
+ /*
+ * There is no way to check if the kernel supports soft-dirty, other
+ * than by writing to a page and seeing if the bit was set. But the
+ * tests are intended to check that the bit gets set when it should, so
+ * doing that check would turn a potentially legitimate fail into a
+ * skip. Fortunately, we know for sure that arm64 does not support
+ * soft-dirty. So for now, let's just use the arch as a corse guide.
+ */
+#if defined(__aarch64__)
+ return 0;
+#else
+ return 1;
+#endif
+}
+
int main(int argc, char **argv)
{
+ int nr_tests = 16;
int err;
pagesize = getpagesize();
+ if (system_has_softdirty())
+ nr_tests += 5;
+
ksft_print_header();
- ksft_set_plan(21);
+ ksft_set_plan(nr_tests);
sense_support();
test_prot_read();
@@ -279,7 +300,8 @@ int main(int argc, char **argv)
test_holes();
test_populate_read();
test_populate_write();
- test_softdirty();
+ if (system_has_softdirty())
+ test_softdirty();
err = ksft_get_fail_cnt();
if (err)
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 3f26f6e15b2a..9e4338aa5e09 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -290,7 +290,10 @@ then
CATEGORY="pkey" run_test ./protection_keys_64
fi
-CATEGORY="soft_dirty" run_test ./soft-dirty
+if [ -x ./soft-dirty ]
+then
+ CATEGORY="soft_dirty" run_test ./soft-dirty
+fi
# COW tests
CATEGORY="cow" run_test ./cow
--
2.25.1
