1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2022 Google LLC
4 */
5#define _GNU_SOURCE
6#include <errno.h>
7#include <stdbool.h>
8#include <stdio.h>
9#include <stdlib.h>
10#include <sys/syscall.h>
11#include <sys/wait.h>
12#include <unistd.h>
13#include <asm-generic/unistd.h>
14#include "vm_util.h"
15#include "../kselftest.h"
16
17#define MB(x) (x << 20)
18#define MAX_SIZE_MB 1024
19
20static int alloc_noexit(unsigned long nr_pages, int pipefd)
21{
22	int ppid = getppid();
23	int timeout = 10; /* 10sec timeout to get killed */
24	unsigned long i;
25	char *buf;
26
27	buf = (char *)mmap(NULL, nr_pages * psize(), PROT_READ | PROT_WRITE,
28			   MAP_PRIVATE | MAP_ANON, 0, 0);
29	if (buf == MAP_FAILED)
30		ksft_exit_fail_msg("mmap failed, halting the test: %s\n", strerror(errno));
31
32	for (i = 0; i < nr_pages; i++)
33		*((unsigned long *)(buf + (i * psize()))) = i;
34
35	/* Signal the parent that the child is ready */
36	if (write(pipefd, "", 1) < 0)
37		ksft_exit_fail_msg("write: %s\n", strerror(errno));
38
39	/* Wait to be killed (when reparenting happens) */
40	while (getppid() == ppid && timeout > 0) {
41		sleep(1);
42		timeout--;
43	}
44
45	munmap(buf, nr_pages * psize());
46
47	return (timeout > 0) ? KSFT_PASS : KSFT_FAIL;
48}
49
50/* The process_mrelease calls in this test are expected to fail */
51static void run_negative_tests(int pidfd)
52{
53	/* Test invalid flags. Expect to fail with EINVAL error code. */
54	if (!syscall(__NR_process_mrelease, pidfd, (unsigned int)-1) ||
55			errno != EINVAL) {
56		ksft_exit_fail_msg("process_mrelease with wrong flags: %s\n", strerror(errno));
57	}
58	/*
59	 * Test reaping while process is alive with no pending SIGKILL.
60	 * Expect to fail with EINVAL error code.
61	 */
62	if (!syscall(__NR_process_mrelease, pidfd, 0) || errno != EINVAL)
63		ksft_exit_fail_msg("process_mrelease on a live process: %s\n", strerror(errno));
64}
65
66static int child_main(int pipefd[], size_t size)
67{
68	int res;
69
70	/* Allocate and fault-in memory and wait to be killed */
71	close(pipefd[0]);
72	res = alloc_noexit(MB(size) / psize(), pipefd[1]);
73	close(pipefd[1]);
74	return res;
75}
76
77int main(void)
78{
79	int pipefd[2], pidfd;
80	bool success, retry;
81	size_t size;
82	pid_t pid;
83	char byte;
84	int res;
85
86	ksft_print_header();
87	ksft_set_plan(1);
88
89	/* Test a wrong pidfd */
90	if (!syscall(__NR_process_mrelease, -1, 0) || errno != EBADF) {
91		if (errno == ENOSYS) {
92			ksft_test_result_skip("process_mrelease not implemented\n");
93			ksft_finished();
94		} else {
95			ksft_exit_fail_msg("process_mrelease with wrong pidfd: %s",
96					   strerror(errno));
97		}
98	}
99
100	/* Start the test with 1MB child memory allocation */
101	size = 1;
102retry:
103	/*
104	 * Pipe for the child to signal when it's done allocating
105	 * memory
106	 */
107	if (pipe(pipefd))
108		ksft_exit_fail_msg("pipe: %s\n", strerror(errno));
109
110	pid = fork();
111	if (pid < 0) {
112		close(pipefd[0]);
113		close(pipefd[1]);
114		ksft_exit_fail_msg("fork: %s\n", strerror(errno));
115	}
116
117	if (pid == 0) {
118		/* Child main routine */
119		res = child_main(pipefd, size);
120		exit(res);
121	}
122
123	/*
124	 * Parent main routine:
125	 * Wait for the child to finish allocations, then kill and reap
126	 */
127	close(pipefd[1]);
128	/* Block until the child is ready */
129	res = read(pipefd[0], &byte, 1);
130	close(pipefd[0]);
131	if (res < 0) {
132		if (!kill(pid, SIGKILL))
133			waitpid(pid, NULL, 0);
134		ksft_exit_fail_msg("read: %s\n", strerror(errno));
135	}
136
137	pidfd = syscall(__NR_pidfd_open, pid, 0);
138	if (pidfd < 0) {
139		if (!kill(pid, SIGKILL))
140			waitpid(pid, NULL, 0);
141		ksft_exit_fail_msg("pidfd_open: %s\n", strerror(errno));
142	}
143
144	/* Run negative tests which require a live child */
145	run_negative_tests(pidfd);
146
147	if (kill(pid, SIGKILL))
148		ksft_exit_fail_msg("kill: %s\n", strerror(errno));
149
150	success = (syscall(__NR_process_mrelease, pidfd, 0) == 0);
151	if (!success) {
152		/*
153		 * If we failed to reap because the child exited too soon,
154		 * before we could call process_mrelease. Double child's memory
155		 * which causes it to spend more time on cleanup and increases
156		 * our chances of reaping its memory before it exits.
157		 * Retry until we succeed or reach MAX_SIZE_MB.
158		 */
159		if (errno == ESRCH) {
160			retry = (size <= MAX_SIZE_MB);
161		} else {
162			waitpid(pid, NULL, 0);
163			ksft_exit_fail_msg("process_mrelease: %s\n", strerror(errno));
164		}
165	}
166
167	/* Cleanup to prevent zombies */
168	if (waitpid(pid, NULL, 0) < 0)
169		ksft_exit_fail_msg("waitpid: %s\n", strerror(errno));
170
171	close(pidfd);
172
173	if (!success) {
174		if (retry) {
175			size *= 2;
176			goto retry;
177		}
178		ksft_exit_fail_msg("All process_mrelease attempts failed!\n");
179	}
180
181	ksft_test_result_pass("Success reaping a child with %zuMB of memory allocations\n",
182			      size);
183	ksft_finished();
184}
185