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selftests/mm: skip soft-dirty tests on arm64

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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.

Link: https://lkml.kernel.org/r/20230724082522.1202616-3-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ryan Roberts 2023-07-24 09:25:16 +01:00 committed by Andrew Morton
parent 58e2847ad2
commit f6dd4e223d
3 changed files with 32 additions and 4 deletions
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5
tools/testing/selftests/mm/Makefile
View file

@ -64,12 +64,15 @@ 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)

26
tools/testing/selftests/mm/madv_populate.c
View file

@ -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)

5
tools/testing/selftests/mm/run_vmtests.sh
View file

@ -322,7 +322,10 @@ 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