The patch titled
Subject: selftests/hmm-tests: add test for dirty bits
has been added to the -mm mm-unstable branch. Its filename is
selftests-hmm-tests-add-test-for-dirty-bits.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.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: selftests/hmm-tests: add test for dirty bits
Date: Tue, 16 Aug 2022 17:39:25 +1000
We were not correctly copying PTE dirty bits to pages during
migrate_vma_setup() calls. This could potentially lead to data loss, so
add a test for this.
Link: https://lkml.kernel.org/r/23069a5c6e07d16d4c4f0951ff003591ffc4f656.1660635033.git-series.apopple@xxxxxxxxxx
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Alex Sierra <alex.sierra@xxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Felix Kuehling <felix.kuehling@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Karol Herbst <kherbst@xxxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/hmm-tests.c | 124 +++++++++++++++++++++++
1 file changed, 124 insertions(+)
--- a/tools/testing/selftests/vm/hmm-tests.c~selftests-hmm-tests-add-test-for-dirty-bits
+++ a/tools/testing/selftests/vm/hmm-tests.c
@@ -1240,6 +1240,130 @@ TEST_F(hmm, migrate_multiple)
}
}
+static char cgroup[] = "/sys/fs/cgroup/hmm-test-XXXXXX";
+static int write_cgroup_param(char *cgroup_path, char *param, long value)
+{
+ int ret;
+ FILE *f;
+ char *filename;
+
+ if (asprintf(&filename, "%s/%s", cgroup_path, param) < 0)
+ return -1;
+
+ f = fopen(filename, "w");
+ if (!f) {
+ ret = -1;
+ goto out;
+ }
+
+ ret = fprintf(f, "%ld\n", value);
+ if (ret < 0)
+ goto out1;
+
+ ret = 0;
+
+out1:
+ fclose(f);
+out:
+ free(filename);
+
+ return ret;
+}
+
+static int setup_cgroup(void)
+{
+ pid_t pid = getpid();
+ int ret;
+
+ if (!mkdtemp(cgroup))
+ return -1;
+
+ ret = write_cgroup_param(cgroup, "cgroup.procs", pid);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int destroy_cgroup(void)
+{
+ pid_t pid = getpid();
+ int ret;
+
+ ret = write_cgroup_param("/sys/fs/cgroup/cgroup.procs",
+ "cgroup.proc", pid);
+ if (ret)
+ return ret;
+
+ if (rmdir(cgroup))
+ return -1;
+
+ return 0;
+}
+
+/*
+ * Try and migrate a dirty page that has previously been swapped to disk. This
+ * checks that we don't loose dirty bits.
+ */
+TEST_F(hmm, migrate_dirty_page)
+{
+ struct hmm_buffer *buffer;
+ unsigned long npages;
+ unsigned long size;
+ unsigned long i;
+ int *ptr;
+ int tmp = 0;
+
+ npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+ ASSERT_NE(npages, 0);
+ size = npages << self->page_shift;
+
+ buffer = malloc(sizeof(*buffer));
+ ASSERT_NE(buffer, NULL);
+
+ buffer->fd = -1;
+ buffer->size = size;
+ buffer->mirror = malloc(size);
+ ASSERT_NE(buffer->mirror, NULL);
+
+ ASSERT_EQ(setup_cgroup(), 0);
+
+ buffer->ptr = mmap(NULL, size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ buffer->fd, 0);
+ ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+ /* Initialize buffer in system memory. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = 0;
+
+ ASSERT_FALSE(write_cgroup_param(cgroup, "memory.reclaim", 1UL<<30));
+
+ /* Fault pages back in from swap as clean pages */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ tmp += ptr[i];
+
+ /* Dirty the pte */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ptr[i] = i;
+
+ /*
+ * Attempt to migrate memory to device, which should fail because
+ * hopefully some pages are backed by swap storage.
+ */
+ ASSERT_TRUE(hmm_migrate_sys_to_dev(self->fd, buffer, npages));
+
+ ASSERT_FALSE(write_cgroup_param(cgroup, "memory.reclaim", 1UL<<30));
+
+ /* Check we still see the updated data after restoring from swap. */
+ for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+ ASSERT_EQ(ptr[i], i);
+
+ hmm_buffer_free(buffer);
+ destroy_cgroup();
+}
+
/*
* Read anonymous memory multiple times.
*/
_
Patches currently in -mm which might be from apopple@xxxxxxxxxx are
mm-migrate_devicec-copy-pte-dirty-bit-to-page.patch
mm-gupc-simplify-and-fix-check_and_migrate_movable_pages-return-codes.patch
selftests-hmm-tests-add-test-for-dirty-bits.patch
