mm/migrate: add migrate-shared test for migrate_vma_*()

Add a migrate_vma_*() self test for mmap(MAP_SHARED) to verify that
!vma_anonymous() ranges won't be migrated.

Signed-off-by: Ralph Campbell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Cc: Jerome Glisse <[e-mail]>
Cc: John Hubbard <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: "Bharata B Rao" <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Linus Torvalds <[e-mail]>

tools/testing/selftests/vm/hmm-tests.c

···
 }
 
 /*
+ * Migrate anonymous shared memory to device private memory.
+ */
+TEST_F(hmm, migrate_shared)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	int ret;
+
+	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);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_SHARED | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Migrate memory to device. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_MIGRATE, buffer, npages);
+	ASSERT_EQ(ret, -ENOENT);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
  * Try to migrate various memory types to device private memory.
  */
 TEST_F(hmm2, migrate_mixed)