[PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[Chunyu Hu]

There are several tests requires transprarent hugepages, when run on thp
disabled kernel such as realtime kernel, there will be false negative.
Mark those tests as skip when thp is not available.

Changes in v3:
  - patch 1 update commit message to show the log snippet with where the
    fail happens, change the 'false positive' to 'false negative'.
    Update reviwed by
  - patch 2 update reviewed-by
  - patch 3 make write_file to void return
  - patch 4 and patch 5 updated reviewed-by/acked-by

Changes in v2:
  - replace 'false postive' with 'false negative' in cover letter
  - patch 1 and patch 2 add reviewed-by/acked-by
  - new patch 3 to add write_file() in vm_util as a common helper
  - patch 4 removed the {} in if block, removed the write_file helper
    rename chunk in v1. Add reviewed-by
  - patch 5 move the exit chunk to the front of ksft_print_headers() as
    suggested by David.  Add review by.

Chunyu Hu (5):
  selftests/mm/guard-regions: skip collapse test when thp not enabled
  selftests/mm: soft-dirty: skip two tests when thp is not available
  selftests/mm: move write_file helper to vm_util
  selftests/mm: split_huge_page_test: skip the test when thp is not
    available
  selftests/mm: transhuge_stress: skip the test when thp not available

 tools/testing/selftests/mm/guard-regions.c    |  4 ++++
 tools/testing/selftests/mm/soft-dirty.c       |  4 +++-
 .../selftests/mm/split_huge_page_test.c       | 19 ++++-----------
 tools/testing/selftests/mm/thp_settings.c     | 24 +------------------
 tools/testing/selftests/mm/thp_settings.h     |  1 -
 tools/testing/selftests/mm/transhuge-stress.c |  4 ++++
 tools/testing/selftests/mm/vm_util.c          | 16 +++++++++++++
 tools/testing/selftests/mm/vm_util.h          |  2 ++
 8 files changed, 34 insertions(+), 40 deletions(-)


base-commit: f338e77383789c0cae23ca3d48adcc5e9e137e3c
-- 
2.53.0

[PATCH v3 1/5] selftests/mm/guard-regions: skip collapse test when thp not enabled

[Chunyu Hu]

When thp is not available, just skip the collape tests to avoid the false
negative.

Without the change, run with a thp disabled kernel:
  ./run_vmtests.sh -t madv_guard -n 1
  <snip/>
  #  RUN           guard_regions.anon.collapse ...
  # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
  # collapse: Test terminated by assertion
  #          FAIL  guard_regions.anon.collapse
  not ok 2 guard_regions.anon.collapse
  <snip/>
  #  RUN           guard_regions.shmem.collapse ...
  # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
  # collapse: Test terminated by assertion
  #          FAIL  guard_regions.shmem.collapse
  not ok 32 guard_regions.shmem.collapse
  <snip/>
  #  RUN           guard_regions.file.collapse ...
  # guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
  # collapse: Test terminated by assertion
  #          FAIL  guard_regions.file.collapse
  not ok 62 guard_regions.file.collapse
  <snip/>
  # FAILED: 87 / 90 tests passed.
  # 17 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
  # Totals: pass:70 fail:3 xfail:0 xpass:0 skip:17 error:0

With this change, run with thp disabled kernel:
  ./run_vmtests.sh -t madv_guard -n 1
  <snip/>
  #  RUN           guard_regions.anon.collapse ...
  #      SKIP      Transparent Hugepages not available
  #            OK  guard_regions.anon.collapse
  ok 2 guard_regions.anon.collapse # SKIP Transparent Hugepages not available
  <snip/>
  #  RUN           guard_regions.file.collapse ...
  #      SKIP      Transparent Hugepages not available
  #            OK  guard_regions.file.collapse
  ok 62 guard_regions.file.collapse # SKIP Transparent Hugepages not available
  <snip/>
  #  RUN           guard_regions.shmem.collapse ...
  #      SKIP      Transparent Hugepages not available
  #            OK  guard_regions.shmem.collapse
  ok 32 guard_regions.shmem.collapse # SKIP Transparent Hugepages not available
  <snip/>
  # PASSED: 90 / 90 tests passed.
  # 20 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
  # Totals: pass:70 fail:0 xfail:0 xpass:0 skip:20 error:0

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
CC: Li Wang <liwang@redhat.com>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
Changes in v3:
  - commit message: update the log snippet with where the fail happens and
    add the '-n1' to the command.
  - fix the 'false positive' to 'false negative'
  - add reviwed by from Mike
Changes in v2:
  - add reviewed by from Zi and Lorenzo
  - add acked-by from David
---
 tools/testing/selftests/mm/guard-regions.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
index dbd21d66d383..897af9c512f9 100644
--- a/tools/testing/selftests/mm/guard-regions.c
+++ b/tools/testing/selftests/mm/guard-regions.c
@@ -21,6 +21,7 @@
 #include <sys/uio.h>
 #include <unistd.h>
 #include "vm_util.h"
+#include "thp_settings.h"
 
 #include "../pidfd/pidfd.h"
 
@@ -2195,6 +2196,9 @@ TEST_F(guard_regions, collapse)
 	char *ptr;
 	int i;
 
+	if (!thp_is_enabled())
+		SKIP(return, "Transparent Hugepages not available\n");
+
 	/* Need file to be correct size for tests for non-anon. */
 	if (variant->backing != ANON_BACKED)
 		ASSERT_EQ(ftruncate(self->fd, size), 0);

base-commit: 2d1373e4246da3b58e1df058374ed6b101804e07
-- 
2.53.0

[PATCH v3 2/5] selftests/mm: soft-dirty: skip two tests when thp is not available

[Chunyu Hu]

The test_hugepage test contain two sub tests. If just reporting one skip
when thp not available, there will be error in the log because the test
count don't match the test plan. Change to skip two tests by running the
ksft_test_result_skip twice in this case.

Without the fix (run test on thp disabled kernel):
  ./run_vmtests.sh -t soft_dirty
  # --------------------
  # running ./soft-dirty
  # --------------------
  # TAP version 13
  # 1..19
  # ok 1 Test test_simple
  # ok 2 Test test_vma_reuse dirty bit of allocated page
  # ok 3 Test test_vma_reuse dirty bit of reused address page
  # ok 4 # SKIP Transparent Hugepages not available
  # ok 5 Test test_mprotect-anon dirty bit of new written page
  # ok 6 Test test_mprotect-anon soft-dirty clear after clear_refs
  # ok 7 Test test_mprotect-anon soft-dirty clear after marking RO
  # ok 8 Test test_mprotect-anon soft-dirty clear after marking RW
  # ok 9 Test test_mprotect-anon soft-dirty after rewritten
  # ok 10 Test test_mprotect-file dirty bit of new written page
  # ok 11 Test test_mprotect-file soft-dirty clear after clear_refs
  # ok 12 Test test_mprotect-file soft-dirty clear after marking RO
  # ok 13 Test test_mprotect-file soft-dirty clear after marking RW
  # ok 14 Test test_mprotect-file soft-dirty after rewritten
  # ok 15 Test test_merge-anon soft-dirty after remap merge 1st pg
  # ok 16 Test test_merge-anon soft-dirty after remap merge 2nd pg
  # ok 17 Test test_merge-anon soft-dirty after mprotect merge 1st pg
  # ok 18 Test test_merge-anon soft-dirty after mprotect merge 2nd pg
  # # 1 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
  # # Planned tests != run tests (19 != 18)
  # # Totals: pass:17 fail:0 xfail:0 xpass:0 skip:1 error:0
  # [FAIL]
  not ok 52 soft-dirty # exit=1

With the fix (run test on thp disabled kernel):
  ./run_vmtests.sh -t soft_dirty
  # --------------------
  # running ./soft-dirty
  # TAP version 13
  # --------------------
  # running ./soft-dirty
  # --------------------
  # TAP version 13
  # 1..19
  # ok 1 Test test_simple
  # ok 2 Test test_vma_reuse dirty bit of allocated page
  # ok 3 Test test_vma_reuse dirty bit of reused address page
  # # Transparent Hugepages not available
  # ok 4 # SKIP Test test_hugepage huge page allocation
  # ok 5 # SKIP Test test_hugepage huge page dirty bit
  # ok 6 Test test_mprotect-anon dirty bit of new written page
  # ok 7 Test test_mprotect-anon soft-dirty clear after clear_refs
  # ok 8 Test test_mprotect-anon soft-dirty clear after marking RO
  # ok 9 Test test_mprotect-anon soft-dirty clear after marking RW
  # ok 10 Test test_mprotect-anon soft-dirty after rewritten
  # ok 11 Test test_mprotect-file dirty bit of new written page
  # ok 12 Test test_mprotect-file soft-dirty clear after clear_refs
  # ok 13 Test test_mprotect-file soft-dirty clear after marking RO
  # ok 14 Test test_mprotect-file soft-dirty clear after marking RW
  # ok 15 Test test_mprotect-file soft-dirty after rewritten
  # ok 16 Test test_merge-anon soft-dirty after remap merge 1st pg
  # ok 17 Test test_merge-anon soft-dirty after remap merge 2nd pg
  # ok 18 Test test_merge-anon soft-dirty after mprotect merge 1st pg
  # ok 19 Test test_merge-anon soft-dirty after mprotect merge 2nd pg
  # # 2 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
  # # Totals: pass:17 fail:0 xfail:0 xpass:0 skip:2 error:0
  # [PASS]
  ok 1 soft-dirty
  hwpoison_inject
  # SUMMARY: PASS=1 SKIP=0 FAIL=0
  1..1

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
CC: Li Wang <liwang@redhat.com>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
Changes in v3:
  - Add reviewed by from Mike
Changes in v2:
  - add reviewed by from Lorenzo and Zi
  - add acked-by from David
---
 tools/testing/selftests/mm/soft-dirty.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
index 59c0dbe99a9b..bcfcac99b436 100644
--- a/tools/testing/selftests/mm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -82,7 +82,9 @@ static void test_hugepage(int pagemap_fd, int pagesize)
 	int i, ret;
 
 	if (!thp_is_enabled()) {
-		ksft_test_result_skip("Transparent Hugepages not available\n");
+		ksft_print_msg("Transparent Hugepages not available\n");
+		ksft_test_result_skip("Test %s huge page allocation\n", __func__);
+		ksft_test_result_skip("Test %s huge page dirty bit\n", __func__);
 		return;
 	}
 
-- 
2.53.0

[PATCH v3 3/5] selftests/mm: move write_file helper to vm_util

[Chunyu Hu]

thp_settings provides write_file() helper for safely writing to a file and
exit when write failure happens. It's a very low level helper and many sub
tests need such a helper, not only thp tests.

split_huge_page_test also defines a write_file locally. The two have minior
differences in return type and used exit api. And there would be conflicts
if split_huge_page_test wanted to include thp_settings.h because of
different prototype, making it less convenient.

It's possisble to merge the two, although some tests don't use the
kselftest infrastrucutre for testing. It would also work when using the
ksft_exit_msg() to exit in my test, as the counters are all zero. Output
will be like:

  TAP version 13
  1..62
  Bail out! /proc/sys/vm/drop_caches1 open failed: No such file or directory
  # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0

So here we just keep the version in split_huge_page_test, and move it into
the vm_util. This makes it easy to maitain and user could just include one
vm_util.h when they don't need thp setting helpers. Keep the prototype of
void return as the function will exit on any error, return value is not
necessary, and will simply the callers like write_num() and write_string().

Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
Changes in v3:
  - make the write_file void return
Changes in v2:
  new patch from v2
---
 .../selftests/mm/split_huge_page_test.c       | 15 --------
 tools/testing/selftests/mm/thp_settings.c     | 35 ++-----------------
 tools/testing/selftests/mm/thp_settings.h     |  1 -
 tools/testing/selftests/mm/vm_util.c          | 15 ++++++++
 tools/testing/selftests/mm/vm_util.h          |  2 ++
 5 files changed, 20 insertions(+), 48 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index e0167111bdd1..93f205327b84 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -255,21 +255,6 @@ static int check_after_split_folio_orders(char *vaddr_start, size_t len,
 	return status;
 }
 
-static void write_file(const char *path, const char *buf, size_t buflen)
-{
-	int fd;
-	ssize_t numwritten;
-
-	fd = open(path, O_WRONLY);
-	if (fd == -1)
-		ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno));
-
-	numwritten = write(fd, buf, buflen - 1);
-	close(fd);
-	if (numwritten < 1)
-		ksft_exit_fail_msg("Write failed\n");
-}
-
 static void write_debugfs(const char *fmt, ...)
 {
 	char input[INPUT_MAX];
diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
index 574bd0f8ae48..e748ebfb3d4e 100644
--- a/tools/testing/selftests/mm/thp_settings.c
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "vm_util.h"
 #include "thp_settings.h"
 
 #define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
@@ -64,29 +65,6 @@ int read_file(const char *path, char *buf, size_t buflen)
 	return (unsigned int) numread;
 }
 
-int write_file(const char *path, const char *buf, size_t buflen)
-{
-	int fd;
-	ssize_t numwritten;
-
-	fd = open(path, O_WRONLY);
-	if (fd == -1) {
-		printf("open(%s)\n", path);
-		exit(EXIT_FAILURE);
-		return 0;
-	}
-
-	numwritten = write(fd, buf, buflen - 1);
-	close(fd);
-	if (numwritten < 1) {
-		printf("write(%s)\n", buf);
-		exit(EXIT_FAILURE);
-		return 0;
-	}
-
-	return (unsigned int) numwritten;
-}
-
 unsigned long read_num(const char *path)
 {
 	char buf[21];
@@ -104,10 +82,7 @@ void write_num(const char *path, unsigned long num)
 	char buf[21];
 
 	sprintf(buf, "%ld", num);
-	if (!write_file(path, buf, strlen(buf) + 1)) {
-		perror(path);
-		exit(EXIT_FAILURE);
-	}
+	write_file(path, buf, strlen(buf) + 1);
 }
 
 int thp_read_string(const char *name, const char * const strings[])
@@ -165,11 +140,7 @@ void thp_write_string(const char *name, const char *val)
 		printf("%s: Pathname is too long\n", __func__);
 		exit(EXIT_FAILURE);
 	}
-
-	if (!write_file(path, val, strlen(val) + 1)) {
-		perror(path);
-		exit(EXIT_FAILURE);
-	}
+	write_file(path, val, strlen(val) + 1);
 }
 
 unsigned long thp_read_num(const char *name)
diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
index 76eeb712e5f1..7748a9009191 100644
--- a/tools/testing/selftests/mm/thp_settings.h
+++ b/tools/testing/selftests/mm/thp_settings.h
@@ -63,7 +63,6 @@ struct thp_settings {
 };
 
 int read_file(const char *path, char *buf, size_t buflen);
-int write_file(const char *path, const char *buf, size_t buflen);
 unsigned long read_num(const char *path);
 void write_num(const char *path, unsigned long num);
 
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index a6d4ff7dfdc0..ad96d19d1b85 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -764,3 +764,18 @@ int unpoison_memory(unsigned long pfn)
 
 	return ret > 0 ? 0 : -errno;
 }
+
+void write_file(const char *path, const char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numwritten;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno));
+
+	numwritten = write(fd, buf, buflen - 1);
+	close(fd);
+	if (numwritten < 1)
+		ksft_exit_fail_msg("Write failed\n");
+}
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index e9c4e24769c1..1a07305ceff4 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -166,3 +166,5 @@ int unpoison_memory(unsigned long pfn);
 
 #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
 #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
+
+void write_file(const char *path, const char *buf, size_t buflen);
-- 
2.53.0

[PATCH v3 4/5] selftests/mm: split_huge_page_test: skip the test when thp is not available

[Chunyu Hu]

When thp is not enabled on some kernel config such as realtime kernel, the
test will report failure. Fix the false positive by skipping the test
directly when thp is not enabled.

Tested with thp disabled kernel:
Before The fix:
  # --------------------------------------------------
  # running ./split_huge_page_test /tmp/xfs_dir_Ywup9p
  # --------------------------------------------------
  # TAP version 13
  # Bail out! Reading PMD pagesize failed
  # # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
  # [FAIL]
  not ok 61 split_huge_page_test /tmp/xfs_dir_Ywup9p # exit=1

After the fix:
  # --------------------------------------------------
  # running ./split_huge_page_test /tmp/xfs_dir_YHPUPl
  # --------------------------------------------------
  # TAP version 13
  # 1..0 # SKIP Transparent Hugepages not available
  # [SKIP]
  ok 6 split_huge_page_test /tmp/xfs_dir_YHPUPl # SKIP

Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
CC: Li Wang <liwang@redhat.com>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
V3 chagnes:
  - add acked-by from David
  - add reviewed by from Mike
V2 changes:
  - removed the {} in if block
  - removed the write_file helper rename chunk, as there's a new patch 3 to
    resolve the conflict with thp_settings.h by moving it to vm_util.
  - Add reviewed by from Zi and Lorenzo
---
 tools/testing/selftests/mm/split_huge_page_test.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 93f205327b84..500d07c4938b 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -21,6 +21,7 @@
 #include <time.h>
 #include "vm_util.h"
 #include "kselftest.h"
+#include "thp_settings.h"
 
 uint64_t pagesize;
 unsigned int pageshift;
@@ -757,6 +758,9 @@ int main(int argc, char **argv)
 		ksft_finished();
 	}
 
+	if (!thp_is_enabled())
+		ksft_exit_skip("Transparent Hugepages not available\n");
+
 	if (argc > 1)
 		optional_xfs_path = argv[1];
 
-- 
2.53.0

[PATCH v3 5/5] selftests/mm: transhuge_stress: skip the test when thp not available

[Chunyu Hu]

The test requires thp, skip the test when thp is not available to avoid
false positive.

Tested with thp disabled kernel.
Before the fix:
  # --------------------------------
  # running ./transhuge-stress -d 20
  # --------------------------------
  # TAP version 13
  # 1..1
  # transhuge-stress: allocate 1453 transhuge pages, using 2907 MiB virtual memory and 11 MiB of ram
  # Bail out! MADV_HUGEPAGE# Planned tests != run tests (1 != 0)
  # # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
  # [FAIL]
  not ok 60 transhuge-stress -d 20 # exit=1

After the fix:
  # --------------------------------
  # running ./transhuge-stress -d 20
  # --------------------------------
  # TAP version 13
  # 1..0 # SKIP Transparent Hugepages not available
  # [SKIP]
  ok 5 transhuge-stress -d 20 # SKIP

Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
CC: Li Wang <liwang@redhat.com>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
---
V3 changes:
  - Add review by from Mike
  - Add acked-by from David
V2 changes:
  - Move the exit chunk to the front of ksft_print_headers() as suggested
    by David.
  - Add reviewed by from Zi and Lorenzo
---
 tools/testing/selftests/mm/transhuge-stress.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/mm/transhuge-stress.c b/tools/testing/selftests/mm/transhuge-stress.c
index bcad47c09518..7a9f1035099b 100644
--- a/tools/testing/selftests/mm/transhuge-stress.c
+++ b/tools/testing/selftests/mm/transhuge-stress.c
@@ -17,6 +17,7 @@
 #include <sys/mman.h>
 #include "vm_util.h"
 #include "kselftest.h"
+#include "thp_settings.h"
 
 int backing_fd = -1;
 int mmap_flags = MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE;
@@ -37,6 +38,9 @@ int main(int argc, char **argv)
 
 	ksft_print_header();
 
+	if (!thp_is_enabled())
+		ksft_exit_skip("Transparent Hugepages not available\n");
+
 	ram = sysconf(_SC_PHYS_PAGES);
 	if (ram > SIZE_MAX / psize() / 4)
 		ram = SIZE_MAX / 4;
-- 
2.53.0

Re: [PATCH v3 3/5] selftests/mm: move write_file helper to vm_util

[David Hildenbrand (Arm)]

>  
>  int thp_read_string(const char *name, const char * const strings[])
> @@ -165,11 +140,7 @@ void thp_write_string(const char *name, const char *val)
>  		printf("%s: Pathname is too long\n", __func__);
>  		exit(EXIT_FAILURE);
>  	}
> -
> -	if (!write_file(path, val, strlen(val) + 1)) {
> -		perror(path);
> -		exit(EXIT_FAILURE);
> -	}
> +	write_file(path, val, strlen(val) + 1);

Wondering what happens if a test like migration.c that uses
kselftest_harness.h ends up calling ksft_exit_fail_msg().

I assume the ksft_exit_fail* will simply set exit(KSFT_FAIL) and make
the __wait_for_test() helper happy.

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David

Re: [PATCH v3 3/5] selftests/mm: move write_file helper to vm_util

[Lorenzo Stoakes (Oracle)]

On Tue, Mar 17, 2026 at 05:44:17PM +0800, Chunyu Hu wrote:
> thp_settings provides write_file() helper for safely writing to a file and
> exit when write failure happens. It's a very low level helper and many sub
> tests need such a helper, not only thp tests.
>
> split_huge_page_test also defines a write_file locally. The two have minior
> differences in return type and used exit api. And there would be conflicts
> if split_huge_page_test wanted to include thp_settings.h because of
> different prototype, making it less convenient.
>
> It's possisble to merge the two, although some tests don't use the
> kselftest infrastrucutre for testing. It would also work when using the
> ksft_exit_msg() to exit in my test, as the counters are all zero. Output
> will be like:
>
>   TAP version 13
>   1..62
>   Bail out! /proc/sys/vm/drop_caches1 open failed: No such file or directory
>   # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> So here we just keep the version in split_huge_page_test, and move it into
> the vm_util. This makes it easy to maitain and user could just include one
> vm_util.h when they don't need thp setting helpers. Keep the prototype of
> void return as the function will exit on any error, return value is not
> necessary, and will simply the callers like write_num() and write_string().
>
> Suggested-by: Mike Rapoport <rppt@kernel.org>
> Signed-off-by: Chunyu Hu <chuhu@redhat.com>

LGTM and broadly a good idea, I do share David's concern about what if tests
that don't use the usual framework have an issue, but really that's an issue
with _those tests_ more so than this.

Anyway, nice cleanup so:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

> ---
> Changes in v3:
>   - make the write_file void return
> Changes in v2:
>   new patch from v2
> ---
>  .../selftests/mm/split_huge_page_test.c       | 15 --------
>  tools/testing/selftests/mm/thp_settings.c     | 35 ++-----------------
>  tools/testing/selftests/mm/thp_settings.h     |  1 -
>  tools/testing/selftests/mm/vm_util.c          | 15 ++++++++
>  tools/testing/selftests/mm/vm_util.h          |  2 ++
>  5 files changed, 20 insertions(+), 48 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
> index e0167111bdd1..93f205327b84 100644
> --- a/tools/testing/selftests/mm/split_huge_page_test.c
> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
> @@ -255,21 +255,6 @@ static int check_after_split_folio_orders(char *vaddr_start, size_t len,
>  	return status;
>  }
>
> -static void write_file(const char *path, const char *buf, size_t buflen)
> -{
> -	int fd;
> -	ssize_t numwritten;
> -
> -	fd = open(path, O_WRONLY);
> -	if (fd == -1)
> -		ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno));
> -
> -	numwritten = write(fd, buf, buflen - 1);
> -	close(fd);
> -	if (numwritten < 1)
> -		ksft_exit_fail_msg("Write failed\n");
> -}
> -
>  static void write_debugfs(const char *fmt, ...)
>  {
>  	char input[INPUT_MAX];
> diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
> index 574bd0f8ae48..e748ebfb3d4e 100644
> --- a/tools/testing/selftests/mm/thp_settings.c
> +++ b/tools/testing/selftests/mm/thp_settings.c
> @@ -6,6 +6,7 @@
>  #include <string.h>
>  #include <unistd.h>
>
> +#include "vm_util.h"
>  #include "thp_settings.h"
>
>  #define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
> @@ -64,29 +65,6 @@ int read_file(const char *path, char *buf, size_t buflen)
>  	return (unsigned int) numread;
>  }
>
> -int write_file(const char *path, const char *buf, size_t buflen)
> -{
> -	int fd;
> -	ssize_t numwritten;
> -
> -	fd = open(path, O_WRONLY);
> -	if (fd == -1) {
> -		printf("open(%s)\n", path);
> -		exit(EXIT_FAILURE);
> -		return 0;
> -	}
> -
> -	numwritten = write(fd, buf, buflen - 1);
> -	close(fd);
> -	if (numwritten < 1) {
> -		printf("write(%s)\n", buf);
> -		exit(EXIT_FAILURE);
> -		return 0;
> -	}
> -
> -	return (unsigned int) numwritten;
> -}
> -
>  unsigned long read_num(const char *path)
>  {
>  	char buf[21];
> @@ -104,10 +82,7 @@ void write_num(const char *path, unsigned long num)
>  	char buf[21];
>
>  	sprintf(buf, "%ld", num);
> -	if (!write_file(path, buf, strlen(buf) + 1)) {
> -		perror(path);
> -		exit(EXIT_FAILURE);
> -	}
> +	write_file(path, buf, strlen(buf) + 1);
>  }
>
>  int thp_read_string(const char *name, const char * const strings[])
> @@ -165,11 +140,7 @@ void thp_write_string(const char *name, const char *val)
>  		printf("%s: Pathname is too long\n", __func__);
>  		exit(EXIT_FAILURE);
>  	}
> -
> -	if (!write_file(path, val, strlen(val) + 1)) {
> -		perror(path);
> -		exit(EXIT_FAILURE);
> -	}
> +	write_file(path, val, strlen(val) + 1);
>  }
>
>  unsigned long thp_read_num(const char *name)
> diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
> index 76eeb712e5f1..7748a9009191 100644
> --- a/tools/testing/selftests/mm/thp_settings.h
> +++ b/tools/testing/selftests/mm/thp_settings.h
> @@ -63,7 +63,6 @@ struct thp_settings {
>  };
>
>  int read_file(const char *path, char *buf, size_t buflen);
> -int write_file(const char *path, const char *buf, size_t buflen);
>  unsigned long read_num(const char *path);
>  void write_num(const char *path, unsigned long num);
>
> diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
> index a6d4ff7dfdc0..ad96d19d1b85 100644
> --- a/tools/testing/selftests/mm/vm_util.c
> +++ b/tools/testing/selftests/mm/vm_util.c
> @@ -764,3 +764,18 @@ int unpoison_memory(unsigned long pfn)
>
>  	return ret > 0 ? 0 : -errno;
>  }
> +
> +void write_file(const char *path, const char *buf, size_t buflen)
> +{
> +	int fd;
> +	ssize_t numwritten;
> +
> +	fd = open(path, O_WRONLY);
> +	if (fd == -1)
> +		ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno));
> +
> +	numwritten = write(fd, buf, buflen - 1);
> +	close(fd);
> +	if (numwritten < 1)
> +		ksft_exit_fail_msg("Write failed\n");
> +}
> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
> index e9c4e24769c1..1a07305ceff4 100644
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -166,3 +166,5 @@ int unpoison_memory(unsigned long pfn);
>
>  #define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
>  #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
> +
> +void write_file(const char *path, const char *buf, size_t buflen);
> --
> 2.53.0
>

Re: [PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[Andrew Morton]

On Tue, 17 Mar 2026 17:44:14 +0800 Chunyu Hu <chuhu@redhat.com> wrote:

> There are several tests requires transprarent hugepages, when run on thp
> disabled kernel such as realtime kernel, there will be false negative.
> Mark those tests as skip when thp is not available.

AI review asked some questions:
https://sashiko.dev/#/patchset/20260317094419.1429259-1-chuhu%40redhat.com

Re: [PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[Chunyu Hu]

On Tue, Mar 17, 2026 at 11:37:30AM -0700, Andrew Morton wrote:
> On Tue, 17 Mar 2026 17:44:14 +0800 Chunyu Hu <chuhu@redhat.com> wrote:
> 
> > There are several tests requires transprarent hugepages, when run on thp
> > disabled kernel such as realtime kernel, there will be false negative.
> > Mark those tests as skip when thp is not available.
> 
> AI review asked some questions:
> https://sashiko.dev/#/patchset/20260317094419.1429259-1-chuhu%40redhat.com

Hi Andrew,

Nice tool.
 
For question one. In guard-region test, collapse tests are for checking
collapse is denied when operating on guard region, not for checking
madvise(MADV_COLLAPSE) will fail when thp is setup to 'never with sysfs,
result is same, but it's a different test. Maybe we don't have strong
interest to test when thp is set to 'never' in this collapse test.
Do you perfer we let it run when thp is setup with 'never'?

For question two. In soft dirty test. Yes, test_mprotect skip logic has
similar issue when open failed. 'Bail out' would be shown. Maybe we
do this in other series or you prefer me to fix it in this series?

For question three. Add buffer length check in write_file() helper and
check if written bytes equal expected bytes. It's easy to add a buffer
lenghth check and make it robust. It's not easy to do the partial
written check as that will make the helper more complex and need one
more parameter as expected written bytes. Maybe for such question, we
should do with other series, not in this one?

Thanks!

Re: [PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[Lorenzo Stoakes (Oracle)]

On Wed, Mar 18, 2026 at 05:22:40PM +0800, Chunyu Hu wrote:
> For question one. In guard-region test, collapse tests are for checking
> collapse is denied when operating on guard region, not for checking
> madvise(MADV_COLLAPSE) will fail when thp is setup to 'never with sysfs,

No, if thp is set to never, madvise(MADV_COLLAPSE) still succeeds. This is a
source of confusion for many :)

> result is same, but it's a different test. Maybe we don't have strong
> interest to test when thp is set to 'never' in this collapse test.
> Do you perfer we let it run when thp is setup with 'never'?

Yes because it should still function then :)

Cheers, Lorenzo

Re: [PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[David Hildenbrand (Arm)]

On 3/18/26 10:22, Chunyu Hu wrote:
> On Tue, Mar 17, 2026 at 11:37:30AM -0700, Andrew Morton wrote:
>> On Tue, 17 Mar 2026 17:44:14 +0800 Chunyu Hu <chuhu@redhat.com> wrote:
>>
>>> There are several tests requires transprarent hugepages, when run on thp
>>> disabled kernel such as realtime kernel, there will be false negative.
>>> Mark those tests as skip when thp is not available.
>>
>> AI review asked some questions:
>> https://sashiko.dev/#/patchset/20260317094419.1429259-1-chuhu%40redhat.com
> 
> Hi Andrew,
> 
> Nice tool.
>  
> For question one. In guard-region test, collapse tests are for checking
> collapse is denied when operating on guard region, not for checking
> madvise(MADV_COLLAPSE) will fail when thp is setup to 'never with sysfs,
> result is same, but it's a different test. Maybe we don't have strong
> interest to test when thp is set to 'never' in this collapse test.
> Do you perfer we let it run when thp is setup with 'never'?
> 
> For question two. In soft dirty test. Yes, test_mprotect skip logic has
> similar issue when open failed. 'Bail out' would be shown. Maybe we
> do this in other series or you prefer me to fix it in this series?

IMHO, that's something for another series (if at all).

> 
> For question three. Add buffer length check in write_file() helper and
> check if written bytes equal expected bytes. It's easy to add a buffer
> lenghth check and make it robust. It's not easy to do the partial
> written check as that will make the helper more complex and need one
> more parameter as expected written bytes. Maybe for such question, we
> should do with other series, not in this one?

The AI brings up many things that are irrelevant in practice (in
particular for tests). So I wouldn't worry about that. You are only
moving code.

-- 
Cheers,

David

Re: [PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[Chunyu Hu]

On Wed, Mar 18, 2026 at 11:32:10AM +0000, Lorenzo Stoakes (Oracle) wrote:
> On Wed, Mar 18, 2026 at 05:22:40PM +0800, Chunyu Hu wrote:
> > For question one. In guard-region test, collapse tests are for checking
> > collapse is denied when operating on guard region, not for checking
> > madvise(MADV_COLLAPSE) will fail when thp is setup to 'never with sysfs,
> 
> No, if thp is set to never, madvise(MADV_COLLAPSE) still succeeds. This is a
> source of confusion for many :)

You are right. Thanks for correcting me.

> 
> > result is same, but it's a different test. Maybe we don't have strong
> > interest to test when thp is set to 'never' in this collapse test.
> > Do you perfer we let it run when thp is setup with 'never'?
> 
> Yes because it should still function then :)

Sure. Let me send a v4 to change to thp_available().

> 
> Cheers, Lorenzo
> 

Re: [PATCH v3 0/5] selftests/mm: skip several tests when thp is not available

[Chunyu Hu]

On Wed, Mar 18, 2026 at 01:07:03PM +0100, David Hildenbrand (Arm) wrote:
> On 3/18/26 10:22, Chunyu Hu wrote:
> > On Tue, Mar 17, 2026 at 11:37:30AM -0700, Andrew Morton wrote:
> >> On Tue, 17 Mar 2026 17:44:14 +0800 Chunyu Hu <chuhu@redhat.com> wrote:
> >>
> >>> There are several tests requires transprarent hugepages, when run on thp
> >>> disabled kernel such as realtime kernel, there will be false negative.
> >>> Mark those tests as skip when thp is not available.
> >>
> >> AI review asked some questions:
> >> https://sashiko.dev/#/patchset/20260317094419.1429259-1-chuhu%40redhat.com
> > 
> > Hi Andrew,
> > 
> > Nice tool.
> >  
> > For question one. In guard-region test, collapse tests are for checking
> > collapse is denied when operating on guard region, not for checking
> > madvise(MADV_COLLAPSE) will fail when thp is setup to 'never with sysfs,
> > result is same, but it's a different test. Maybe we don't have strong
> > interest to test when thp is set to 'never' in this collapse test.
> > Do you perfer we let it run when thp is setup with 'never'?
> > 
> > For question two. In soft dirty test. Yes, test_mprotect skip logic has
> > similar issue when open failed. 'Bail out' would be shown. Maybe we
> > do this in other series or you prefer me to fix it in this series?
> 
> IMHO, that's something for another series (if at all).

OK. Then will not touch it here.

> 
> > 
> > For question three. Add buffer length check in write_file() helper and
> > check if written bytes equal expected bytes. It's easy to add a buffer
> > lenghth check and make it robust. It's not easy to do the partial
> > written check as that will make the helper more complex and need one
> > more parameter as expected written bytes. Maybe for such question, we
> > should do with other series, not in this one?
> 
> The AI brings up many things that are irrelevant in practice (in
> particular for tests). So I wouldn't worry about that. You are only
> moving code.

Yes. Then I don't change it here. Thanks.

> 
> -- 
> Cheers,
> 
> David
>