* [PATCH v4 1/3] mm/ksm: fix ksm exec support for prctl
2024-03-28 11:10 [PATCH v4 0/3] mm/ksm: fix ksm exec support for prctl Jinjiang Tu
@ 2024-03-28 11:10 ` Jinjiang Tu
2024-03-28 11:10 ` [PATCH v4 2/3] selftest/mm: ksm_functional_tests: refactor mmap_and_merge_range() Jinjiang Tu
2024-03-28 11:10 ` [PATCH v4 3/3] selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec Jinjiang Tu
2 siblings, 0 replies; 6+ messages in thread
From: Jinjiang Tu @ 2024-03-28 11:10 UTC (permalink / raw)
To: akpm, david, shr, hannes, riel, wangkefeng.wang, sunnanyong, linux-mm
Cc: tujinjiang
commit 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") inherits
MMF_VM_MERGE_ANY flag when a task calls execve(). Howerver, it doesn't
create the mm_slot, so ksmd will not try to scan this task.
To fix it, allocate and add the mm_slot to ksm_mm_head in __bprm_mm_init()
when the mm has MMF_VM_MERGE_ANY flag.
Fixes: 3c6f33b7273a ("mm/ksm: support fork/exec for prctl")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
fs/exec.c | 11 +++++++++++
include/linux/ksm.h | 13 +++++++++++++
2 files changed, 24 insertions(+)
diff --git a/fs/exec.c b/fs/exec.c
index ff6f26671cfc..c2890d32232e 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -67,6 +67,7 @@
#include <linux/time_namespace.h>
#include <linux/user_events.h>
#include <linux/rseq.h>
+#include <linux/ksm.h>
#include <linux/uaccess.h>
#include <asm/mmu_context.h>
@@ -267,6 +268,14 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
goto err_free;
}
+ /*
+ * Need to be called with mmap write lock
+ * held, to avoid race with ksmd.
+ */
+ err = ksm_execve(mm);
+ if (err)
+ goto err_ksm;
+
/*
* Place the stack at the largest stack address the architecture
* supports. Later, we'll move this to an appropriate place. We don't
@@ -288,6 +297,8 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
bprm->p = vma->vm_end - sizeof(void *);
return 0;
err:
+ ksm_exit(mm);
+err_ksm:
mmap_write_unlock(mm);
err_free:
bprm->vma = NULL;
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 401348e9f92b..7e2b1de3996a 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -59,6 +59,14 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
return 0;
}
+static inline int ksm_execve(struct mm_struct *mm)
+{
+ if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))
+ return __ksm_enter(mm);
+
+ return 0;
+}
+
static inline void ksm_exit(struct mm_struct *mm)
{
if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
@@ -107,6 +115,11 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
return 0;
}
+static inline int ksm_execve(struct mm_struct *mm)
+{
+ return 0;
+}
+
static inline void ksm_exit(struct mm_struct *mm)
{
}
--
2.25.1
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v4 2/3] selftest/mm: ksm_functional_tests: refactor mmap_and_merge_range()
2024-03-28 11:10 [PATCH v4 0/3] mm/ksm: fix ksm exec support for prctl Jinjiang Tu
2024-03-28 11:10 ` [PATCH v4 1/3] " Jinjiang Tu
@ 2024-03-28 11:10 ` Jinjiang Tu
2024-03-28 11:30 ` David Hildenbrand
2024-03-28 11:10 ` [PATCH v4 3/3] selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec Jinjiang Tu
2 siblings, 1 reply; 6+ messages in thread
From: Jinjiang Tu @ 2024-03-28 11:10 UTC (permalink / raw)
To: akpm, david, shr, hannes, riel, wangkefeng.wang, sunnanyong, linux-mm
Cc: tujinjiang
In order to extend test_prctl_fork() and test_prctl_fork_exec() to make
sure that deduplication really happens, mmap_and_merge_range() needs to be
refactored.
Firstly, mmap_and_merge_range() will be called with no need to call enable
KSM by madvise or prctl. So, switch the 'bool use_prctl' parameter to enum
ksm_merge_mode.
Secondly, mmap_and_merge_range() will be called in child process in the
two testcases, it isn't appropriate to call ksft_test_result_{fail, skip},
because the global variables ksft_{fail, skip} aren't consistent with the
parent process. Thus, convert calls of ksft_test_result_{fail, skip} to
ksft_print_msg(), return differrent error according to the two cases, and
rename mmap_and_merge_range() to __mmap_and_merge_range(). For existing
callers, introduce new mmap_and_merge_range() to handle different return
values of __mmap_and_merge_range().
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
.../selftests/mm/ksm_functional_tests.c | 86 +++++++++++++------
1 file changed, 61 insertions(+), 25 deletions(-)
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index d615767e396b..5462873df84c 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -28,6 +28,15 @@
#define MiB (1024 * KiB)
#define FORK_EXEC_CHILD_PRG_NAME "ksm_fork_exec_child"
+#define MAP_MERGE_FAIL ((void *)-1)
+#define MAP_MERGE_SKIP ((void *)-2)
+
+enum ksm_merge_mode {
+ KSM_MERGE_PRCTL,
+ KSM_MERGE_MADVISE,
+ KSM_MERGE_NONE, /* PRCTL already set */
+};
+
static int mem_fd;
static int ksm_fd;
static int ksm_full_scans_fd;
@@ -146,33 +155,34 @@ static int ksm_unmerge(void)
return 0;
}
-static char *mmap_and_merge_range(char val, unsigned long size, int prot,
- bool use_prctl)
+static char *__mmap_and_merge_range(char val, unsigned long size, int prot,
+ enum ksm_merge_mode mode)
{
char *map;
+ char *err_map = MAP_MERGE_FAIL;
int ret;
/* Stabilize accounting by disabling KSM completely. */
if (ksm_unmerge()) {
- ksft_test_result_fail("Disabling (unmerging) KSM failed\n");
- return MAP_FAILED;
+ ksft_print_msg("Disabling (unmerging) KSM failed\n");
+ return err_map;
}
if (get_my_merging_pages() > 0) {
- ksft_test_result_fail("Still pages merged\n");
- return MAP_FAILED;
+ ksft_print_msg("Still pages merged\n");
+ return err_map;
}
map = mmap(NULL, size, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANON, -1, 0);
if (map == MAP_FAILED) {
- ksft_test_result_fail("mmap() failed\n");
- return MAP_FAILED;
+ ksft_print_msg("mmap() failed\n");
+ return err_map;
}
/* Don't use THP. Ignore if THP are not around on a kernel. */
if (madvise(map, size, MADV_NOHUGEPAGE) && errno != EINVAL) {
- ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
+ ksft_print_msg("MADV_NOHUGEPAGE failed\n");
goto unmap;
}
@@ -180,27 +190,36 @@ static char *mmap_and_merge_range(char val, unsigned long size, int prot,
memset(map, val, size);
if (mprotect(map, size, prot)) {
- ksft_test_result_skip("mprotect() failed\n");
+ ksft_print_msg("mprotect() failed\n");
+ err_map = MAP_MERGE_SKIP;
goto unmap;
}
- if (use_prctl) {
+ switch (mode) {
+ case KSM_MERGE_PRCTL:
ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);
if (ret < 0 && errno == EINVAL) {
- ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n");
+ ksft_print_msg("PR_SET_MEMORY_MERGE not supported\n");
+ err_map = MAP_MERGE_SKIP;
goto unmap;
} else if (ret) {
- ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n");
+ ksft_print_msg("PR_SET_MEMORY_MERGE=1 failed\n");
goto unmap;
}
- } else if (madvise(map, size, MADV_MERGEABLE)) {
- ksft_test_result_fail("MADV_MERGEABLE failed\n");
- goto unmap;
+ break;
+ case KSM_MERGE_MADVISE:
+ if (madvise(map, size, MADV_MERGEABLE)) {
+ ksft_print_msg("MADV_MERGEABLE failed\n");
+ goto unmap;
+ }
+ break;
+ case KSM_MERGE_NONE:
+ break;
}
/* Run KSM to trigger merging and wait. */
if (ksm_merge()) {
- ksft_test_result_fail("Running KSM failed\n");
+ ksft_print_msg("Running KSM failed\n");
goto unmap;
}
@@ -209,14 +228,31 @@ static char *mmap_and_merge_range(char val, unsigned long size, int prot,
* accounted differently (depending on kernel support).
*/
if (val && !get_my_merging_pages()) {
- ksft_test_result_fail("No pages got merged\n");
+ ksft_print_msg("No pages got merged\n");
goto unmap;
}
return map;
unmap:
munmap(map, size);
- return MAP_FAILED;
+ return err_map;
+}
+
+static char *mmap_and_merge_range(char val, unsigned long size, int prot,
+ enum ksm_merge_mode mode)
+{
+ char *map;
+ char *ret = MAP_FAILED;
+
+ map = __mmap_and_merge_range(val, size, prot, mode);
+ if (map == MAP_MERGE_FAIL)
+ ksft_test_result_fail("Merging memory failed");
+ else if (map == MAP_MERGE_SKIP)
+ ksft_test_result_skip("Merging memory skipped");
+ else
+ ret = map;
+
+ return ret;
}
static void test_unmerge(void)
@@ -226,7 +262,7 @@ static void test_unmerge(void)
ksft_print_msg("[RUN] %s\n", __func__);
- map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false);
+ map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_MADVISE);
if (map == MAP_FAILED)
return;
@@ -264,7 +300,7 @@ static void test_unmerge_zero_pages(void)
}
/* Let KSM deduplicate zero pages. */
- map = mmap_and_merge_range(0x00, size, PROT_READ | PROT_WRITE, false);
+ map = mmap_and_merge_range(0x00, size, PROT_READ | PROT_WRITE, KSM_MERGE_MADVISE);
if (map == MAP_FAILED)
return;
@@ -312,7 +348,7 @@ static void test_unmerge_discarded(void)
ksft_print_msg("[RUN] %s\n", __func__);
- map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false);
+ map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_MADVISE);
if (map == MAP_FAILED)
return;
@@ -344,7 +380,7 @@ static void test_unmerge_uffd_wp(void)
ksft_print_msg("[RUN] %s\n", __func__);
- map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false);
+ map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_MADVISE);
if (map == MAP_FAILED)
return;
@@ -545,7 +581,7 @@ static void test_prctl_unmerge(void)
ksft_print_msg("[RUN] %s\n", __func__);
- map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, true);
+ map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_PRCTL);
if (map == MAP_FAILED)
return;
@@ -568,7 +604,7 @@ static void test_prot_none(void)
ksft_print_msg("[RUN] %s\n", __func__);
- map = mmap_and_merge_range(0x11, size, PROT_NONE, false);
+ map = mmap_and_merge_range(0x11, size, PROT_NONE, KSM_MERGE_MADVISE);
if (map == MAP_FAILED)
goto unmap;
--
2.25.1
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v4 3/3] selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec
2024-03-28 11:10 [PATCH v4 0/3] mm/ksm: fix ksm exec support for prctl Jinjiang Tu
2024-03-28 11:10 ` [PATCH v4 1/3] " Jinjiang Tu
2024-03-28 11:10 ` [PATCH v4 2/3] selftest/mm: ksm_functional_tests: refactor mmap_and_merge_range() Jinjiang Tu
@ 2024-03-28 11:10 ` Jinjiang Tu
2024-03-28 11:33 ` David Hildenbrand
2 siblings, 1 reply; 6+ messages in thread
From: Jinjiang Tu @ 2024-03-28 11:10 UTC (permalink / raw)
To: akpm, david, shr, hannes, riel, wangkefeng.wang, sunnanyong, linux-mm
Cc: tujinjiang
This extends test_prctl_fork() and test_prctl_fork_exec() to make sure
that deduplication really happens, instead of only testing the
MMF_VM_MERGE_ANY flag is set.
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
.../selftests/mm/ksm_functional_tests.c | 49 ++++++++++++++-----
1 file changed, 38 insertions(+), 11 deletions(-)
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index 5462873df84c..2d277620fad2 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -475,6 +475,36 @@ static void test_prctl(void)
ksft_test_result_pass("Setting/clearing PR_SET_MEMORY_MERGE works\n");
}
+static int test_child_ksm(void)
+{
+ const unsigned int size = 2 * MiB;
+ char *map;
+
+ /* Test if KSM is enabled for the process. */
+ if (prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) != 1)
+ return -1;
+
+ /* Test if merge could really happen. */
+ map = __mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, KSM_MERGE_NONE);
+ if (map == MAP_MERGE_FAIL)
+ return -2;
+ else if (map == MAP_MERGE_SKIP)
+ return -3;
+
+ munmap(map, size);
+ return 0;
+}
+
+static void test_child_ksm_err(int status)
+{
+ if (status == -1)
+ ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n");
+ else if (status == -2)
+ ksft_test_result_fail("Merge in child failed\n");
+ else if (status == -3)
+ ksft_test_result_skip("Merge in child skiped\n");
+}
+
/* Verify that prctl ksm flag is inherited. */
static void test_prctl_fork(void)
{
@@ -494,7 +524,7 @@ static void test_prctl_fork(void)
child_pid = fork();
if (!child_pid) {
- exit(prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0));
+ exit(test_child_ksm());
} else if (child_pid < 0) {
ksft_test_result_fail("fork() failed\n");
return;
@@ -503,8 +533,11 @@ static void test_prctl_fork(void)
if (waitpid(child_pid, &status, 0) < 0) {
ksft_test_result_fail("waitpid() failed\n");
return;
- } else if (WEXITSTATUS(status) != 1) {
- ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n");
+ }
+
+ status = WEXITSTATUS(status);
+ if (status) {
+ test_child_ksm_err(status);
return;
}
@@ -516,12 +549,6 @@ static void test_prctl_fork(void)
ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
}
-static int ksm_fork_exec_child(void)
-{
- /* Test if KSM is enabled for the process. */
- return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) == 1;
-}
-
static void test_prctl_fork_exec(void)
{
int ret, status;
@@ -554,7 +581,7 @@ static void test_prctl_fork_exec(void)
if (WIFEXITED(status)) {
status = WEXITSTATUS(status);
if (status) {
- ksft_test_result_fail("KSM not enabled\n");
+ test_child_ksm_err(status);
return;
}
} else {
@@ -635,7 +662,7 @@ int main(int argc, char **argv)
int err;
if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
- exit(ksm_fork_exec_child() == 1 ? 0 : 1);
+ exit(test_child_ksm());
}
#ifdef __NR_userfaultfd
--
2.25.1
^ permalink raw reply [flat|nested] 6+ messages in thread