The patch titled
Subject: hmm-tests: fix migrate_dirty_page test
has been added to the -mm mm-unstable branch. Its filename is
selftests-hmm-tests-add-test-for-dirty-bits-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-hmm-tests-add-test-for-dirty-bits-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alistair Popple <apopple@xxxxxxxxxx>
Subject: hmm-tests: fix migrate_dirty_page test
Date: Wed, 14 Sep 2022 19:12:05 +1000
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.
Link: https://lkml.kernel.org/r/20220914091205.557676-1-apopple@xxxxxxxxxx
Fixes: 5cc88e844e87 ("selftests/hmm-tests: add test for dirty bits")
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Reviewed-by: Mika Penttilä <mpenttil@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Alex Sierra <alex.sierra@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(-)
--- a/tools/testing/selftests/vm/hmm-tests.c~selftests-hmm-tests-add-test-for-dirty-bits-fix
+++ a/tools/testing/selftests/vm/hmm-tests.c
@@ -33,6 +33,7 @@
*/
#include "../../../../lib/test_hmm_uapi.h"
#include "../../../../mm/gup_test.h"
+#include "vm_util.h"
struct hmm_buffer {
void *ptr;
@@ -1301,9 +1302,24 @@ 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)
{
@@ -1340,6 +1356,10 @@ 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];
@@ -1349,10 +1369,10 @@ 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));
--- a/tools/testing/selftests/vm/Makefile~selftests-hmm-tests-add-test-for-dirty-bits-fix
+++ a/tools/testing/selftests/vm/Makefile
@@ -98,6 +98,7 @@ 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))
--- a/tools/testing/selftests/vm/vm_util.c~selftests-hmm-tests-add-test-for-dirty-bits-fix
+++ a/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
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 *
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;
--- a/tools/testing/selftests/vm/vm_util.h~selftests-hmm-tests-add-test-for-dirty-bits-fix
+++ a/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);
_
Patches currently in -mm which might be from apopple@xxxxxxxxxx are
selftests-hmm-tests-add-test-for-dirty-bits.patch
selftests-hmm-tests-add-test-for-dirty-bits-fix.patch
