tools/testing/selftests/mm/process_madv.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/mm/process_madv.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/mm/process_madv.c
Extension
.c
Size
9367 bytes
Lines
373
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct child_info {
		pid_t pid;
		void *map_addr;
	} info;

	huge_page_size = read_pmd_pagesize();
	if (huge_page_size <= 0)
		SKIP(return, "Could not determine a valid huge page size.\n");

	ASSERT_EQ(pipe(pipe_info), 0);

	self->child_pid = fork();
	ASSERT_NE(self->child_pid, -1);

	if (self->child_pid == 0) {
		char *map;
		size_t map_size = 2 * huge_page_size;

		close(pipe_info[0]);

		map = mmap(NULL, map_size, PROT_READ | PROT_WRITE,
			   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
		ASSERT_NE(map, MAP_FAILED);

		/* Fault in as small pages */
		for (size_t i = 0; i < map_size; i += pagesize)
			map[i] = 'A';

		/* Send info and pause */
		info.pid = getpid();
		info.map_addr = map;
		ret = write(pipe_info[1], &info, sizeof(info));
		ASSERT_EQ(ret, sizeof(info));
		close(pipe_info[1]);

		pause();
		exit(0);
	}

	close(pipe_info[1]);

	/* Receive child info */
	ret = read(pipe_info[0], &info, sizeof(info));
	if (ret <= 0) {
		waitpid(self->child_pid, NULL, 0);
		SKIP(return, "Failed to read child info from pipe.\n");
	}
	ASSERT_EQ(ret, sizeof(info));
	close(pipe_info[0]);
	self->child_pid = info.pid;

	self->remote_pidfd = syscall(__NR_pidfd_open, self->child_pid, 0);
	ASSERT_GE(self->remote_pidfd, 0);

	vec.iov_base = info.map_addr;
	vec.iov_len = huge_page_size;

	ret = sys_process_madvise(self->remote_pidfd, &vec, 1, MADV_COLLAPSE,
				  0);
	if (ret == -1) {
		if (errno == EINVAL)
			SKIP(return, "PROCESS_MADV_ADVISE is not supported.\n");
		else if (errno == EPERM)
			SKIP(return,
				   "No process_madvise() permissions, try running as root.\n");
		return;
	}

	ASSERT_EQ(ret, huge_page_size);
}

/*
 * Test process_madvise() with a pidfd for a process that has already
 * exited to ensure correct error handling.
 */
TEST_F(process_madvise, exited_process_pidfd)
{
	const unsigned long pagesize = self->page_size;
	struct iovec vec;
	char *map;
	ssize_t ret;

	map = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1,
		   0);
	if (map == MAP_FAILED)
		SKIP(return, "mmap failed, not enough memory.\n");

	vec.iov_base = map;
	vec.iov_len = pagesize;

Annotation

Implementation Notes