_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)
 {
@@ -124,3 +160,44 @@ bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size)
 {
 	return __check_huge(addr, "ShmemPmdMapped:", nr_hpages, hpage_size);
 }
+
+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/vm/vm_util.h b/tools/testing/selftests/vm/vm_util.h
index 5c35de454e08..470f85fe9594 100644
--- a/tools/testing/selftests/vm/vm_util.h
+++ b/tools/testing/selftests/vm/vm_util.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <stdint.h>
 #include <stdbool.h>
+#include <sys/mman.h>
 
 uint64_t pagemap_get_entry(int fd, char *start);
 bool pagemap_is_softdirty(int fd, char *start);
@@ -10,3 +11,4 @@ uint64_t read_pmd_pagesize(void);
 bool check_huge_anon(void *addr, int nr_hpages, uint64_t hpage_size);
 bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size);
 bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
+bool softdirty_supported(void);
-- 
2.49.0[PATCH 6.1.y 1/1] selftests/mm: skip soft-dirty tests when CONFIG_MEM_SOFT_DIRTY is disabledLance Yang <lance.yang@linux.dev> undefinedstable@vger.kernel.org undefined undefined undefined undefined undefined undefined undefined undefinedS^