selftests/mm: skip soft-dirty tests when CONFIG_MEM_SOFT_DIRTY is disabled

commit 0389c305ef56cbadca4cbef44affc0ec3213ed30 upstream.

The madv_populate and soft-dirty kselftests currently fail on systems
where CONFIG_MEM_SOFT_DIRTY is disabled.

Introduce a new helper softdirty_supported() into vm_util.c/h to ensure
tests are properly skipped when the feature is not enabled.

Link: https://lkml.kernel.org/r/20250917133137.62802-1-lance.yang@linux.dev
Fixes: 9f3265db6ae8 ("selftests: vm: add test for Soft-Dirty PTE bit")
Signed-off-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/testing/selftests/mm/madv_populate.c b/tools/testing/selftests/mm/madv_populate.c
index ef7d911da13e01bd6096272787c4bfd0c2bed383..16f5754b8b1f739fc598ae81e3a3ca2776903227 100644 (file)
--- 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_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_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 bdfa5d085f0099f74a698c0f8c8170aa77565d28..7b91df12ce5b9f501ff907a7e5466ab067f13cfa 100644 (file)
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -193,8 +193,11 @@ int main(int argc, char **argv)
        int pagesize;
 
        ksft_print_header();
-       ksft_set_plan(15);
 
+       if (!softdirty_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 d8d0cf04bb57fd22bd7748fffec6a23c3103e35c..a4a2805d3d3e7c32c45bfaafc38ac53b17007c9f 100644 (file)
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -193,6 +193,42 @@ err_out:
        return rss_anon;
 }
 
+char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len)
+{
+       int ret;
+       FILE *fp;
+       char *entry = NULL;
+       char addr_pattern[MAX_LINE_LENGTH];
+
+       ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-",
+                      (unsigned long)addr);
+       if (ret >= MAX_LINE_LENGTH)
+               ksft_exit_fail_msg("%s: Pattern is too long\n", __func__);
+
+       fp = fopen(SMAP_FILE_PATH, "r");
+       if (!fp)
+               ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__,
+                                  SMAP_FILE_PATH);
+
+       if (!check_for_pattern(fp, addr_pattern, buf, len))
+               goto err_out;
+
+       /* Fetch the pattern in the same block */
+       if (!check_for_pattern(fp, pattern, buf, len))
+               goto err_out;
+
+       /* Trim trailing newline */
+       entry = strchr(buf, '\n');
+       if (entry)
+               *entry = '\0';
+
+       entry = buf + strlen(pattern);
+
+err_out:
+       fclose(fp);
+       return entry;
+}
+
 bool __check_huge(void *addr, char *pattern, int nr_hpages,
                  uint64_t hpage_size)
 {
@@ -384,3 +420,44 @@ unsigned long get_free_hugepages(void)
        fclose(f);
        return fhp;
 }
+
+static bool check_vmflag(void *addr, const char *flag)
+{
+       char buffer[MAX_LINE_LENGTH];
+       const char *flags;
+       size_t flaglen;
+
+       flags = __get_smap_entry(addr, "VmFlags:", buffer, sizeof(buffer));
+       if (!flags)
+               ksft_exit_fail_msg("%s: No VmFlags for %p\n", __func__, addr);
+
+       while (true) {
+               flags += strspn(flags, " ");
+
+               flaglen = strcspn(flags, " ");
+               if (!flaglen)
+                       return false;
+
+               if (flaglen == strlen(flag) && !memcmp(flags, flag, flaglen))
+                       return true;
+
+               flags += flaglen;
+       }
+}
+
+bool softdirty_supported(void)
+{
+       char *addr;
+       bool supported = false;
+       const size_t pagesize = getpagesize();
+
+       /* 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");
+
+       supported = check_vmflag(addr, "sd");
+       munmap(addr, pagesize);
+       return supported;
+}

diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 2eaed82099255e09ffd38ad9714994397f304685..823d07d84ad01fd7ecf05547fd73fcae6cd16011 100644 (file)
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -53,6 +53,7 @@ int uffd_unregister(int uffd, void *addr, uint64_t len);
 int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
                              bool miss, bool wp, bool minor, uint64_t *ioctls);
 unsigned long get_free_hugepages(void);
+bool softdirty_supported(void);
 
 /*
  * On ppc64 this will only work with radix 2M hugepage size