On 17.09.25 07:59, Lance Yang wrote:
From: Lance Yang <lance.y...@linux.dev>
The madv_populate and soft-dirty kselftests currently fail on systems where
CONFIG_MEM_SOFT_DIRTY is disabled.
Introduce a new helper softdirty_is_supported() into vm_util.c/h to ensure
tests are properly skipped when the feature is not enabled.
I'll note that tools/testing/selftests/mm/config contains
CONFIG_MEM_SOFT_DIRTY=y
But yes, the current arm64 handling is nasty, because some other archs
(e.g., riscv) also don't support it yet.
LGTM, some nits below:
Suggested-by: David Hildenbrand <da...@redhat.com>
Signed-off-by: Lance Yang <lance.y...@linux.dev>
---
tools/testing/selftests/mm/madv_populate.c | 21 ++--------------
tools/testing/selftests/mm/soft-dirty.c | 5 +++-
tools/testing/selftests/mm/vm_util.c | 28 ++++++++++++++++++++++
tools/testing/selftests/mm/vm_util.h | 1 +
4 files changed, 35 insertions(+), 20 deletions(-)
diff --git a/tools/testing/selftests/mm/madv_populate.c
b/tools/testing/selftests/mm/madv_populate.c
index b6fabd5c27ed..43dac7783004 100644
--- a/tools/testing/selftests/mm/madv_populate.c
+++ b/tools/testing/selftests/mm/madv_populate.c
@@ -264,23 +264,6 @@ 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;
@@ -288,7 +271,7 @@ int main(int argc, char **argv)
pagesize = getpagesize();
- if (system_has_softdirty())
+ if (softdirty_is_supported())
nr_tests += 5;
ksft_print_header();
@@ -300,7 +283,7 @@ int main(int argc, char **argv)
test_holes();
test_populate_read();
test_populate_write();
- if (system_has_softdirty())
+ if (softdirty_is_supported())
test_softdirty();
err = ksft_get_fail_cnt();
diff --git a/tools/testing/selftests/mm/soft-dirty.c
b/tools/testing/selftests/mm/soft-dirty.c
index 8a3f2b4b2186..98e42d2ac32a 100644
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -200,8 +200,11 @@ int main(int argc, char **argv)
int pagesize;
ksft_print_header();
- ksft_set_plan(15);
+ if (!softdirty_is_supported())
+ ksft_exit_skip("soft-dirty is not support\n");
+
+ ksft_set_plan(15);
pagemap_fd = open(PAGEMAP_FILE_PATH, O_RDONLY);
if (pagemap_fd < 0)
ksft_exit_fail_msg("Failed to open %s\n", PAGEMAP_FILE_PATH);
diff --git a/tools/testing/selftests/mm/vm_util.c
b/tools/testing/selftests/mm/vm_util.c
index 56e9bd541edd..3173335df775 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -449,6 +449,34 @@ bool check_vmflag_pfnmap(void *addr)
return check_vmflag(addr, "pf");
}
+bool softdirty_is_supported(void)
I'd just call it "softdirty_supported" similar to
"pagemap_scan_supported()".
+{
+ char *addr;
+ int ret = 0;
bool supported = false;
+ size_t pagesize;
+
+ /* We know for sure that arm64 does not support soft-dirty. */
+#if defined(__aarch64__)
+ return ret;
+#endif
Just drop this arm special case now.
+ pagesize = getpagesize();
const size_t pagesize = getpagesize();
+ /*
+ * __mmap_complete() always sets VM_SOFTDIRTY for new VMAs, so we
+ * just mmap a small region and check its VmFlags in /proc/self/smaps
+ * for the "sd" flag.
+ */
/* New mappings are expected to be marked with VM_SOFTDIRTY (sd). */
+ addr = mmap(0, pagesize, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+ if (!addr)
+ ksft_exit_fail_msg("mmap failed\n");
+
+ if (check_vmflag(addr, "sd"))
+ ret = 1;
supported = true;
+
+ munmap(addr, pagesize);
+ return ret;
+}
+
--
Cheers
David / dhildenb
