* [PATCH 6.12.y 1/1] selftests/mm: skip soft-dirty tests when CONFIG_MEM_SOFT_DIRTY is disabled
2025-10-13 11:43 FAILED: patch "[PATCH] selftests/mm: skip soft-dirty tests when" failed to apply to 6.12-stable tree gregkh
@ 2025-10-14 2:34 ` Lance Yang
0 siblings, 0 replies; 2+ messages in thread
From: Lance Yang @ 2025-10-14 2:34 UTC (permalink / raw)
To: stable
Cc: linux-mm, ioworker0, Lance Yang, David Hildenbrand,
Lorenzo Stoakes, Shuah Khan, Gabriel Krisman Bertazi,
Andrew Morton
From: Lance Yang <lance.yang@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_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>
(cherry picked from commit 0389c305ef56cbadca4cbef44affc0ec3213ed30)
---
tools/testing/selftests/mm/madv_populate.c | 21 +-----
tools/testing/selftests/mm/soft-dirty.c | 5 +-
tools/testing/selftests/mm/vm_util.c | 77 ++++++++++++++++++++++
tools/testing/selftests/mm/vm_util.h | 1 +
4 files changed, 84 insertions(+), 20 deletions(-)
diff --git a/tools/testing/selftests/mm/madv_populate.c b/tools/testing/selftests/mm/madv_populate.c
index ef7d911da13e..16f5754b8b1f 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_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 bdfa5d085f00..7b91df12ce5b 100644
--- 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 d8d0cf04bb57..a4a2805d3d3e 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -193,6 +193,42 @@ unsigned long rss_anon(void)
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 2eaed8209925..823d07d84ad0 100644
--- 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
--
2.49.0
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