As noted by John Hubbard the original test relied on side effects of the
implementation of migrate_vma_setup() to detect if pages had been
swapped to disk or not. This is subject to change in future so
explicitly check for swap entries via pagemap instead. Fix a spelling
mistake while we're at it.
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Fixes: 5cc88e844e87 ("selftests/hmm-tests: add test for dirty bits")
Reviewed-by: Mika Penttilä <mpenttil@xxxxxxxxxx>
---
Changes for v2:
- Added Mika's Reviewed-by (Thanks!)
- Moved pagemap checks into vm_util.c as suggested by David H.
---
tools/testing/selftests/vm/Makefile | 1 +
tools/testing/selftests/vm/hmm-tests.c | 28 ++++++++++++++++++++++----
tools/testing/selftests/vm/vm_util.c | 22 ++++++++++++++++++++
tools/testing/selftests/vm/vm_util.h | 2 ++
4 files changed, 49 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index d9fa6a9ea584..17e36129efd2 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -100,6 +100,7 @@ include ../lib.mk
$(OUTPUT)/madv_populate: vm_util.c
$(OUTPUT)/soft-dirty: vm_util.c
$(OUTPUT)/split_huge_page_test: vm_util.c
+$(OUTPUT)/hmm-tests: vm_util.c
ifeq ($(MACHINE),x86_64)
BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32))
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/vm/hmm-tests.c
index 70fdb49b59ed..509fe8c5158e 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/vm/hmm-tests.c
@@ -37,6 +37,7 @@
*/
#include "../../../../lib/test_hmm_uapi.h"
#include "../../../../mm/gup_test.h"
+#include "vm_util.h"
struct hmm_buffer {
void *ptr;
@@ -1261,9 +1262,24 @@ static int destroy_cgroup(void)
return 0;
}
+/* Returns true if at least one page in the range is on swap */
+static bool pages_swapped(void *ptr, size_t size)
+{
+ int fd = open("/proc/self/pagemap", O_RDONLY);
+ bool ret;
+
+ if (fd < 0)
+ return false;
+
+ ret = pagemap_range_some_swapped(fd, ptr, size);
+ close(fd);
+
+ return ret;
+}
+
/*
* Try and migrate a dirty page that has previously been swapped to disk. This
- * checks that we don't loose dirty bits.
+ * checks that we don't lose dirty bits.
*/
TEST_F(hmm, migrate_dirty_page)
{
@@ -1300,6 +1316,10 @@ TEST_F(hmm, migrate_dirty_page)
ASSERT_FALSE(write_cgroup_param(cgroup, "memory.reclaim", 1UL<<30));
+ /* Make sure at least some pages got paged to disk. */
+ if (!pages_swapped(buffer->ptr, size))
+ SKIP(return, "Pages weren't swapped when they should have been");
+
/* Fault pages back in from swap as clean pages */
for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
tmp += ptr[i];
@@ -1309,10 +1329,10 @@ TEST_F(hmm, migrate_dirty_page)
ptr[i] = i;
/*
- * Attempt to migrate memory to device, which should fail because
- * hopefully some pages are backed by swap storage.
+ * Attempt to migrate memory to device. This might fail if some pages
+ * are/were backed by swap but that's ok.
*/
- ASSERT_TRUE(hmm_migrate_sys_to_dev(self->fd, buffer, npages));
+ hmm_migrate_sys_to_dev(self->fd, buffer, npages);
ASSERT_FALSE(write_cgroup_param(cgroup, "memory.reclaim", 1UL<<30));
diff --git a/tools/testing/selftests/vm/vm_util.c b/tools/testing/selftests/vm/vm_util.c
index b58ab11a7a30..2768d4f3de4c 100644
--- a/tools/testing/selftests/vm/vm_util.c
+++ b/tools/testing/selftests/vm/vm_util.c
@@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
+#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include "../kselftest.h"
@@ -20,6 +21,14 @@ uint64_t pagemap_get_entry(int fd, char *start)
return entry;
}
+bool pagemap_is_swapped(int fd, char *start)
+{
+ uint64_t entry = pagemap_get_entry(fd, start);
+
+ // Check if swap entry bit (62nd bit) is set
+ return entry & 0x4000000000000000ull;
+}
+
bool pagemap_is_softdirty(int fd, char *start)
{
uint64_t entry = pagemap_get_entry(fd, start);
@@ -28,6 +37,19 @@ bool pagemap_is_softdirty(int fd, char *start)
return entry & 0x0080000000000000ull;
}
+/* Returns true if at least one page in the range is in swap */
+bool pagemap_range_some_swapped(int fd, char *start, size_t len)
+{
+ unsigned long i;
+ unsigned long npages = len / getpagesize();
+
+ for (i = 0; i < npages; i++)
+ if (pagemap_is_swapped(fd, start + i * getpagesize()))
+ return true;
+
+ return false;
+}
+
void clear_softdirty(void)
{
int ret;
diff --git a/tools/testing/selftests/vm/vm_util.h b/tools/testing/selftests/vm/vm_util.h
index 2e512bd57ae1..307e11f72341 100644
--- a/tools/testing/selftests/vm/vm_util.h
+++ b/tools/testing/selftests/vm/vm_util.h
@@ -4,6 +4,8 @@
uint64_t pagemap_get_entry(int fd, char *start);
bool pagemap_is_softdirty(int fd, char *start);
+bool pagemap_is_swapped(int fd, char *start);
+bool pagemap_range_some_swapped(int fd, char *start, size_t len);
void clear_softdirty(void);
uint64_t read_pmd_pagesize(void);
uint64_t check_huge(void *addr);
--
2.35.1
