--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2022 Google LLC
+ */
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "util.h"
+
+#include "../kselftest.h"
+
+#ifndef __NR_pidfd_open
+#define __NR_pidfd_open -1
+#endif
+
+#ifndef __NR_process_mrelease
+#define __NR_process_mrelease -1
+#endif
+
+#define MB(x) (x << 20)
+#define MAX_SIZE_MB 1024
+
+static int alloc_noexit(unsigned long nr_pages, int pipefd)
+{
+ int ppid = getppid();
+ int timeout = 10; /* 10sec timeout to get killed */
+ unsigned long i;
+ char *buf;
+
+ buf = (char *)mmap(NULL, nr_pages * PAGE_SIZE, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON, 0, 0);
+ if (buf == MAP_FAILED) {
+ perror("mmap failed, halting the test");
+ return KSFT_FAIL;
+ }
+
+ for (i = 0; i < nr_pages; i++)
+ *((unsigned long *)(buf + (i * PAGE_SIZE))) = i;
+
+ /* Signal the parent that the child is ready */
+ if (write(pipefd, "", 1) < 0) {
+ perror("write");
+ return KSFT_FAIL;
+ }
+
+ /* Wait to be killed (when reparenting happens) */
+ while (getppid() == ppid && timeout > 0) {
+ sleep(1);
+ timeout--;
+ }
+
+ munmap(buf, nr_pages * PAGE_SIZE);
+
+ return (timeout > 0) ? KSFT_PASS : KSFT_FAIL;
+}
+
+/* The process_mrelease calls in this test are expected to fail */
+static void run_negative_tests(int pidfd)
+{
+ /* Test invalid flags. Expect to fail with EINVAL error code. */
+ if (!syscall(__NR_process_mrelease, pidfd, (unsigned int)-1) ||
+ errno != EINVAL) {
+ perror("process_mrelease with wrong flags");
+ exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+ }
+ /*
+ * Test reaping while process is alive with no pending SIGKILL.
+ * Expect to fail with EINVAL error code.
+ */
+ if (!syscall(__NR_process_mrelease, pidfd, 0) || errno != EINVAL) {
+ perror("process_mrelease on a live process");
+ exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+ }
+}
+
+static int child_main(int pipefd[], size_t size)
+{
+ int res;
+
+ /* Allocate and fault-in memory and wait to be killed */
+ close(pipefd[0]);
+ res = alloc_noexit(MB(size) / PAGE_SIZE, pipefd[1]);
+ close(pipefd[1]);
+ return res;
+}
+
+int main(void)
+{
+ int pipefd[2], pidfd;
+ bool success, retry;
+ size_t size;
+ pid_t pid;
+ char byte;
+ int res;
+
+ /* Test a wrong pidfd */
+ if (!syscall(__NR_process_mrelease, -1, 0) || errno != EBADF) {
+ perror("process_mrelease with wrong pidfd");
+ exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+ }
+
+ /* Start the test with 1MB child memory allocation */
+ size = 1;
+retry:
+ /*
+ * Pipe for the child to signal when it's done allocating
+ * memory
+ */
+ if (pipe(pipefd)) {
+ perror("pipe");
+ exit(KSFT_FAIL);
+ }
+ pid = fork();
+ if (pid < 0) {
+ perror("fork");
+ close(pipefd[0]);
+ close(pipefd[1]);
+ exit(KSFT_FAIL);
+ }
+
+ if (pid == 0) {
+ /* Child main routine */
+ res = child_main(pipefd, size);
+ exit(res);
+ }
+
+ /*
+ * Parent main routine:
+ * Wait for the child to finish allocations, then kill and reap
+ */
+ close(pipefd[1]);
+ /* Block until the child is ready */
+ res = read(pipefd[0], &byte, 1);
+ close(pipefd[0]);
+ if (res < 0) {
+ perror("read");
+ if (!kill(pid, SIGKILL))
+ waitpid(pid, NULL, 0);
+ exit(KSFT_FAIL);
+ }
+
+ pidfd = syscall(__NR_pidfd_open, pid, 0);
+ if (pidfd < 0) {
+ perror("pidfd_open");
+ if (!kill(pid, SIGKILL))
+ waitpid(pid, NULL, 0);
+ exit(KSFT_FAIL);
+ }
+
+ /* Run negative tests which require a live child */
+ run_negative_tests(pidfd);
+
+ if (kill(pid, SIGKILL)) {
+ perror("kill");
+ exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+ }
+
+ success = (syscall(__NR_process_mrelease, pidfd, 0) == 0);
+ if (!success) {
+ /*
+ * If we failed to reap because the child exited too soon,
+ * before we could call process_mrelease. Double child's memory
+ * which causes it to spend more time on cleanup and increases
+ * our chances of reaping its memory before it exits.
+ * Retry until we succeed or reach MAX_SIZE_MB.
+ */
+ if (errno == ESRCH) {
+ retry = (size <= MAX_SIZE_MB);
+ } else {
+ perror("process_mrelease");
+ waitpid(pid, NULL, 0);
+ exit(errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+ }
+ }
+
+ /* Cleanup to prevent zombies */
+ if (waitpid(pid, NULL, 0) < 0) {
+ perror("waitpid");
+ exit(KSFT_FAIL);
+ }
+ close(pidfd);
+
+ if (!success) {
+ if (retry) {
+ size *= 2;
+ goto retry;
+ }
+ printf("All process_mrelease attempts failed!\n");
+ exit(KSFT_FAIL);
+ }
+
+ printf("Success reaping a child with %zuMB of memory allocations\n",
+ size);
+ return KSFT_PASS;
+}
projects / platform / kernel / linux-rpi.git / commitdiff