On 17.07.23 12:31, Ryan Roberts wrote:
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.
Signed-off-by: Ryan Roberts ryan.roberts@arm.com
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 +}
I guess that will also make the compiler remove any traces of test_softdirty()( from the binary.
Acked-by: David Hildenbrand david@redhat.com