This introduces three tests:
1) Sanity check soft dirty basic semantics: allocate area, clean, dirty,
check if the SD bit 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.
Cc: Will Deacon <[email protected]>
Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
--
Changes since V1:
- Fix last minute build break with page_size
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/soft-dirty/.gitignore | 1 +
tools/testing/selftests/soft-dirty/Makefile | 9 +
.../testing/selftests/soft-dirty/soft-dirty.c | 254 ++++++++++++++++++
4 files changed, 265 insertions(+)
create mode 100644 tools/testing/selftests/soft-dirty/.gitignore
create mode 100644 tools/testing/selftests/soft-dirty/Makefile
create mode 100644 tools/testing/selftests/soft-dirty/soft-dirty.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index bc3299a20338..c8dcd7defd33 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -55,6 +55,7 @@ TARGETS += seccomp
TARGETS += sgx
TARGETS += sigaltstack
TARGETS += size
+TARGETS += soft-dirty
TARGETS += sparc64
TARGETS += splice
TARGETS += static_keys
diff --git a/tools/testing/selftests/soft-dirty/.gitignore b/tools/testing/selftests/soft-dirty/.gitignore
new file mode 100644
index 000000000000..cfb0cfda9bdf
--- /dev/null
+++ b/tools/testing/selftests/soft-dirty/.gitignore
@@ -0,0 +1 @@
+soft-dirty
diff --git a/tools/testing/selftests/soft-dirty/Makefile b/tools/testing/selftests/soft-dirty/Makefile
new file mode 100644
index 000000000000..d76ad8e0f10d
--- /dev/null
+++ b/tools/testing/selftests/soft-dirty/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+top_srcdir = ../../../..
+INSTALL_HDR_PATH = $(top_srcdir)/usr
+LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/
+
+CFLAGS += -Wall -I$(LINUX_HDR_PATH) -O0 -g3
+
+TEST_GEN_PROGS := soft-dirty
+include ../lib.mk
diff --git a/tools/testing/selftests/soft-dirty/soft-dirty.c b/tools/testing/selftests/soft-dirty/soft-dirty.c
new file mode 100644
index 000000000000..5a3d1d0e9043
--- /dev/null
+++ b/tools/testing/selftests/soft-dirty/soft-dirty.c
@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <syscall.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <err.h>
+#include <string.h>
+#include <stdbool.h>
+#include <malloc.h>
+
+#define PAGEMAP_PATH "/proc/self/pagemap"
+#define CLEAR_REFS_PATH "/proc/self/clear_refs"
+#define SMAP_PATH "/proc/self/smaps"
+#define MAX_LINE_LENGTH 512
+
+#define TEST_ITERATIONS 10000
+
+#define PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size"
+
+int clear_refs;
+int pagemap;
+
+int pagesize;
+int mmap_size; /* Size of test region */
+
+static void clear_all_refs(void)
+{
+ if (write(clear_refs, "4\n", 2) != 2)
+ printf("%s: failed to clear references\n", __func__);
+}
+
+static void touch_page(char *map, int n)
+{
+ map[(pagesize * n) + 1]++;
+}
+
+static int check_page(char *map, uint64_t n, int clear)
+{
+ uint64_t off;
+ uint64_t buf = 0;
+
+ off = (n + ((uint64_t)map >> 12)) << 3;
+
+ if (lseek(pagemap, off, SEEK_SET) == (off_t) -1)
+ errx(EXIT_FAILURE, "pagemap llseek failed");
+
+ if (read(pagemap, &buf, 8) != 8)
+ errx(EXIT_FAILURE, "pagemap read failed");
+
+ if (clear)
+ clear_all_refs();
+
+ return ((buf >> 55) & 1);
+}
+
+static void test_simple(void)
+{
+ int i;
+ char *map;
+
+ printf("- Test %s:\n", __func__);
+
+ map = aligned_alloc(pagesize, mmap_size);
+ if (!map)
+ errx(EXIT_FAILURE, "mmap");
+
+ clear_all_refs();
+
+ for (i = 0 ; i < TEST_ITERATIONS; i++) {
+ if (check_page(map, 2, 1) == 1) {
+ errx(EXIT_FAILURE, "dirty bit was 1, but should be 0 (i=%d)", i);
+ break;
+ }
+
+ touch_page(map, 2);
+
+ if (check_page(map, 2, 1) == 0) {
+ errx(EXIT_FAILURE, "dirty bit was 0, but should be 1 (i=%d)", i);
+ break;
+ }
+
+ }
+ free(map);
+
+ printf("success\n");
+}
+
+static void test_vma_reuse(void)
+{
+ char *map, *map2;
+
+ printf("- Test %s:\n", __func__);
+
+ map = (char *) 0x900000000000;
+ map = mmap(map, mmap_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (map == MAP_FAILED)
+ errx(EXIT_FAILURE, "mmap");
+
+ clear_all_refs();
+ touch_page(map, 2);
+
+ munmap(map, mmap_size);
+ map2 = mmap(map, mmap_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (map2 == MAP_FAILED)
+ errx(EXIT_FAILURE, "mmap2");
+
+ if (map != map2)
+ errx(EXIT_FAILURE, "map != map2");
+
+ if (check_page(map, 2, 1) == 0)
+ errx(-1, "map/unmap lost dirty");
+
+ munmap(map2, mmap_size);
+
+ printf("success\n");
+}
+
+/*
+ * read_pmd_pagesize(), check_for_pattern() and check_huge() adapted
+ * from 'tools/testing/selftest/vm/split_huge_page_test.c'
+ */
+static uint64_t read_pmd_pagesize(void)
+{
+ int fd;
+ char buf[20];
+ ssize_t num_read;
+
+ fd = open(PMD_SIZE_PATH, O_RDONLY);
+ if (fd == -1)
+ errx(EXIT_FAILURE, "Open hpage_pmd_size failed");
+
+ num_read = read(fd, buf, 19);
+ if (num_read < 1) {
+ close(fd);
+ errx(EXIT_FAILURE, "Read hpage_pmd_size failed");
+ }
+ buf[num_read] = '\0';
+ close(fd);
+
+ return strtoul(buf, NULL, 10);
+}
+
+static bool check_for_pattern(FILE *fp, const char *pattern, char *buf)
+{
+ while (fgets(buf, MAX_LINE_LENGTH, fp) != NULL) {
+ if (!strncmp(buf, pattern, strlen(pattern)))
+ return true;
+ }
+ return false;
+}
+
+static uint64_t check_huge(void *addr)
+{
+ uint64_t thp = 0;
+ int ret;
+ FILE *fp;
+ char buffer[MAX_LINE_LENGTH];
+ char addr_pattern[MAX_LINE_LENGTH];
+
+ ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-",
+ (unsigned long) addr);
+ if (ret >= MAX_LINE_LENGTH)
+ errx(EXIT_FAILURE, "%s: Pattern is too long\n", __func__);
+
+ fp = fopen(SMAP_PATH, "r");
+ if (!fp)
+ errx(EXIT_FAILURE, "%s: Failed to open file %s\n", __func__, SMAP_PATH);
+
+ if (!check_for_pattern(fp, addr_pattern, buffer))
+ goto err_out;
+
+ /*
+ * Fetch the AnonHugePages: in the same block and check the number of
+ * hugepages.
+ */
+ if (!check_for_pattern(fp, "AnonHugePages:", buffer))
+ goto err_out;
+
+ if (sscanf(buffer, "AnonHugePages:%10ld kB", &thp) != 1)
+ errx(EXIT_FAILURE, "Reading smap error\n");
+
+err_out:
+ fclose(fp);
+
+ return thp;
+}
+
+static void test_hugepage(void)
+{
+ char *map;
+ int i, ret;
+ size_t hpage_len = read_pmd_pagesize();
+
+ printf("- Test %s:\n", __func__);
+
+ map = memalign(hpage_len, hpage_len);
+ if (!map)
+ errx(EXIT_FAILURE, "memalign");
+
+ ret = madvise(map, hpage_len, MADV_HUGEPAGE);
+ if (ret)
+ errx(EXIT_FAILURE, "madvise %d", ret);
+
+ for (i = 0; i < hpage_len; i++)
+ map[i] = (char)i;
+
+ if (!check_huge(map))
+ errx(EXIT_FAILURE, "failed to allocate THP");
+
+ clear_all_refs();
+ for (i = 0 ; i < TEST_ITERATIONS ; i++) {
+ if (check_page(map, 2, 1) == 1) {
+ errx(EXIT_FAILURE, "dirty bit was 1, but should be 0 (i=%d)", i);
+ break;
+ }
+
+ touch_page(map, 2);
+
+ if (check_page(map, 2, 1) == 0) {
+ errx(EXIT_FAILURE, "dirty bit was 0, but should be 1 (i=%d)", i);
+ break;
+ }
+ }
+ munmap(map, mmap_size);
+
+ printf("success\n");
+}
+
+int main(int argc, char **argv)
+{
+ pagemap = open(PAGEMAP_PATH, O_RDONLY, 0);
+ if (pagemap < 0)
+ errx(EXIT_FAILURE, "Failed to open %s", PAGEMAP_PATH);
+
+ clear_refs = open(CLEAR_REFS_PATH, O_WRONLY, 0);
+ if (clear_refs < 0)
+ errx(EXIT_FAILURE, "Failed to open %s", CLEAR_REFS_PATH);
+
+ pagesize = getpagesize();
+ mmap_size = 10 * pagesize;
+
+ test_simple();
+ test_vma_reuse();
+ test_hugepage();
+
+ return 0;
+}
--
2.31.0
On Thu, Jun 03, 2021 at 11:15:18AM -0400, Gabriel Krisman Bertazi wrote:
> This introduces three tests:
>
> 1) Sanity check soft dirty basic semantics: allocate area, clean, dirty,
> check if the SD bit 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.
>
> Cc: Will Deacon <[email protected]>
> Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
>
> --
> Changes since V1:
> - Fix last minute build break with page_size
> ---
> tools/testing/selftests/Makefile | 1 +
> tools/testing/selftests/soft-dirty/.gitignore | 1 +
> tools/testing/selftests/soft-dirty/Makefile | 9 +
> .../testing/selftests/soft-dirty/soft-dirty.c | 254 ++++++++++++++++++
> 4 files changed, 265 insertions(+)
> create mode 100644 tools/testing/selftests/soft-dirty/.gitignore
> create mode 100644 tools/testing/selftests/soft-dirty/Makefile
> create mode 100644 tools/testing/selftests/soft-dirty/soft-dirty.c
Although I think adding a test for this is great (and I certainly wouldn't
want to get in the way of that; quite the opposite), I notice that we
already have test_softdirty() in selftests/vm/madv_populate.c. Would we be
better off extending that test instead of introducing another one?
Will
Will Deacon <[email protected]> writes:
> On Thu, Jun 03, 2021 at 11:15:18AM -0400, Gabriel Krisman Bertazi wrote:
>> This introduces three tests:
>>
>> 1) Sanity check soft dirty basic semantics: allocate area, clean, dirty,
>> check if the SD bit 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.
>>
>> Cc: Will Deacon <[email protected]>
>> Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
>>
>> --
>> Changes since V1:
>> - Fix last minute build break with page_size
>> ---
>> tools/testing/selftests/Makefile | 1 +
>> tools/testing/selftests/soft-dirty/.gitignore | 1 +
>> tools/testing/selftests/soft-dirty/Makefile | 9 +
>> .../testing/selftests/soft-dirty/soft-dirty.c | 254 ++++++++++++++++++
>> 4 files changed, 265 insertions(+)
>> create mode 100644 tools/testing/selftests/soft-dirty/.gitignore
>> create mode 100644 tools/testing/selftests/soft-dirty/Makefile
>> create mode 100644 tools/testing/selftests/soft-dirty/soft-dirty.c
>
> Although I think adding a test for this is great (and I certainly wouldn't
> want to get in the way of that; quite the opposite), I notice that we
> already have test_softdirty() in selftests/vm/madv_populate.c. Would we be
> better off extending that test instead of introducing another one?
Hi, Will. Thanks for the review.
Looks like selftests/vm/madv_populate.c was merged after I sent this,
which explains why I missed it. From a quick look, it also doesn't
verify the corner case of I'm checking here. I will look into merging
the two tests, or at least moving this to vm/ and remove the overlap.
Thanks,
--
Gabriel Krisman Bertazi