The patch titled
Subject: selftests: vm: add test for Soft-Dirty PTE bit
has been added to the -mm tree. Its filename is
selftests-vm-add-test-for-soft-dirty-pte-bit.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/selftests-vm-add-test-for-soft-dirty-pte-bit.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/selftests-vm-add-test-for-soft-dirty-pte-bit.patch
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------------------------------------------------------
From: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Subject: selftests: vm: add test for Soft-Dirty PTE bit
This introduces three tests:
1) Sanity check soft dirty basic semantics: allocate area, clean,
dirty, check if the SD bit is flipped.
2) Check VMA reuse: validate the VM_SOFTDIRTY usage
3) Check soft-dirty on huge pages
This was motivated by Will Deacon's fix commit 912efa17e512 ("mm: proc:
Invalidate TLB after clearing soft-dirty page state"). I was tracking the
same issue that he fixed, and this test would have caught it.
Link: https://lkml.kernel.org/r/20220420084036.4101604-2-usama.anjum@xxxxxxxxxxxxx
Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Co-developed-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/.gitignore | 1
tools/testing/selftests/vm/Makefile | 2
tools/testing/selftests/vm/config | 2
tools/testing/selftests/vm/soft-dirty.c | 145 ++++++++++++++++++++++
4 files changed, 150 insertions(+)
--- a/tools/testing/selftests/vm/config~selftests-vm-add-test-for-soft-dirty-pte-bit
+++ a/tools/testing/selftests/vm/config
@@ -4,3 +4,5 @@ CONFIG_TEST_VMALLOC=m
CONFIG_DEVICE_PRIVATE=y
CONFIG_TEST_HMM=m
CONFIG_GUP_TEST=y
+CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_MEM_SOFT_DIRTY=y
--- a/tools/testing/selftests/vm/.gitignore~selftests-vm-add-test-for-soft-dirty-pte-bit
+++ a/tools/testing/selftests/vm/.gitignore
@@ -29,5 +29,6 @@ write_to_hugetlbfs
hmm-tests
memfd_secret
local_config.*
+soft-dirty
split_huge_page_test
ksm_tests
--- a/tools/testing/selftests/vm/Makefile~selftests-vm-add-test-for-soft-dirty-pte-bit
+++ a/tools/testing/selftests/vm/Makefile
@@ -49,6 +49,7 @@ TEST_GEN_FILES += on-fault-limit
TEST_GEN_FILES += thuge-gen
TEST_GEN_FILES += transhuge-stress
TEST_GEN_FILES += userfaultfd
+TEST_GEN_PROGS += soft-dirty
TEST_GEN_PROGS += split_huge_page_test
TEST_GEN_FILES += ksm_tests
@@ -94,6 +95,7 @@ KSFT_KHDR_INSTALL := 1
include ../lib.mk
$(OUTPUT)/madv_populate: vm_util.c
+$(OUTPUT)/soft-dirty: vm_util.c
$(OUTPUT)/split_huge_page_test: vm_util.c
ifeq ($(MACHINE),x86_64)
--- /dev/null
+++ a/tools/testing/selftests/vm/soft-dirty.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <malloc.h>
+#include <sys/mman.h>
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define PAGEMAP_FILE_PATH "/proc/self/pagemap"
+#define TEST_ITERATIONS 10000
+
+static void test_simple(int pagemap_fd, int pagesize)
+{
+ int i;
+ char *map;
+
+ map = aligned_alloc(pagesize, pagesize);
+ if (!map)
+ ksft_exit_fail_msg("mmap failed\n");
+
+ clear_softdirty();
+
+ for (i = 0 ; i < TEST_ITERATIONS; i++) {
+ if (pagemap_is_softdirty(pagemap_fd, map) == 1) {
+ ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i);
+ break;
+ }
+
+ clear_softdirty();
+ // Write something to the page to get the dirty bit enabled on the page
+ map[0]++;
+
+ if (pagemap_is_softdirty(pagemap_fd, map) == 0) {
+ ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i);
+ break;
+ }
+
+ clear_softdirty();
+ }
+ free(map);
+
+ ksft_test_result(i == TEST_ITERATIONS, "Test %s\n", __func__);
+}
+
+static void test_vma_reuse(int pagemap_fd, int pagesize)
+{
+ char *map, *map2;
+
+ map = mmap(NULL, pagesize, (PROT_READ | PROT_WRITE), (MAP_PRIVATE | MAP_ANON), -1, 0);
+ if (map == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed");
+
+ // The kernel always marks new regions as soft dirty
+ ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 1,
+ "Test %s dirty bit of allocated page\n", __func__);
+
+ clear_softdirty();
+ munmap(map, pagesize);
+
+ map2 = mmap(NULL, pagesize, (PROT_READ | PROT_WRITE), (MAP_PRIVATE | MAP_ANON), -1, 0);
+ if (map2 == MAP_FAILED)
+ ksft_exit_fail_msg("mmap failed");
+
+ // Dirty bit is set for new regions even if they are reused
+ if (map == map2)
+ ksft_test_result(pagemap_is_softdirty(pagemap_fd, map2) == 1,
+ "Test %s dirty bit of reused address page\n", __func__);
+ else
+ ksft_test_result_skip("Test %s dirty bit of reused address page\n", __func__);
+
+ munmap(map2, pagesize);
+}
+
+static void test_hugepage(int pagemap_fd, int pagesize)
+{
+ char *map;
+ int i, ret;
+ size_t hpage_len = read_pmd_pagesize();
+
+ map = memalign(hpage_len, hpage_len);
+ if (!map)
+ ksft_exit_fail_msg("memalign failed\n");
+
+ ret = madvise(map, hpage_len, MADV_HUGEPAGE);
+ if (ret)
+ ksft_exit_fail_msg("madvise failed %d\n", ret);
+
+ for (i = 0; i < hpage_len; i++)
+ map[i] = (char)i;
+
+ if (check_huge(map)) {
+ ksft_test_result_pass("Test %s huge page allocation\n", __func__);
+
+ clear_softdirty();
+ for (i = 0 ; i < TEST_ITERATIONS ; i++) {
+ if (pagemap_is_softdirty(pagemap_fd, map) == 1) {
+ ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i);
+ break;
+ }
+
+ clear_softdirty();
+ // Write something to the page to get the dirty bit enabled on the page
+ map[0]++;
+
+ if (pagemap_is_softdirty(pagemap_fd, map) == 0) {
+ ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i);
+ break;
+ }
+ clear_softdirty();
+ }
+
+ ksft_test_result(i == TEST_ITERATIONS, "Test %s huge page dirty bit\n", __func__);
+ } else {
+ // hugepage allocation failed. skip these tests
+ ksft_test_result_skip("Test %s huge page allocation\n", __func__);
+ ksft_test_result_skip("Test %s huge page dirty bit\n", __func__);
+ }
+ free(map);
+}
+
+int main(int argc, char **argv)
+{
+ int pagemap_fd;
+ int pagesize;
+
+ ksft_print_header();
+ ksft_set_plan(5);
+
+ pagemap_fd = open(PAGEMAP_FILE_PATH, O_RDONLY);
+ if (pagemap_fd < 0)
+ ksft_exit_fail_msg("Failed to open %s\n", PAGEMAP_FILE_PATH);
+
+ pagesize = getpagesize();
+
+ test_simple(pagemap_fd, pagesize);
+ test_vma_reuse(pagemap_fd, pagesize);
+ test_hugepage(pagemap_fd, pagesize);
+
+ close(pagemap_fd);
+
+ return ksft_exit_pass();
+}
_
Patches currently in -mm which might be from krisman@xxxxxxxxxxxxx are
selftests-vm-add-test-for-soft-dirty-pte-bit.patch
