Introduce process_mrelease syscall sanity tests. They include tests of invalid pidfd and flags inputs, attempting to call process_mrelease with a live process and a valid usage of process_mrelease. Because process_mrelease has to be used against a process with a pending SIGKILL, it's possible that the process exits before process_mrelease gets called. In such cases we retry the test with a victim that allocates twice more memory up to 1GB. This would require the victim process to spend more time during exit and process_mrelease has a better chance of catching the process before it exits.
Signed-off-by: Suren Baghdasaryan surenb@google.com --- tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/mrelease_test.c | 176 +++++++++++++++++++++ tools/testing/selftests/vm/run_vmtests.sh | 16 ++ 3 files changed, 193 insertions(+) create mode 100644 tools/testing/selftests/vm/mrelease_test.c
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile index 04a49e876a46..733fccbff0ef 100644 --- a/tools/testing/selftests/vm/Makefile +++ b/tools/testing/selftests/vm/Makefile @@ -43,6 +43,7 @@ TEST_GEN_FILES += map_populate TEST_GEN_FILES += memfd_secret TEST_GEN_FILES += mlock-random-test TEST_GEN_FILES += mlock2-tests +TEST_GEN_FILES += mrelease_test TEST_GEN_FILES += mremap_dontunmap TEST_GEN_FILES += mremap_test TEST_GEN_FILES += on-fault-limit diff --git a/tools/testing/selftests/vm/mrelease_test.c b/tools/testing/selftests/vm/mrelease_test.c new file mode 100644 index 000000000000..a61061bf8433 --- /dev/null +++ b/tools/testing/selftests/vm/mrelease_test.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2022 Google LLC + */ +#define _GNU_SOURCE +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "util.h" + +static inline int pidfd_open(pid_t pid, unsigned int flags) +{ +#ifdef __NR_pidfd_open + return syscall(__NR_pidfd_open, pid, flags); +#else + errno = ENOSYS; + return -1; +#endif +} + +static inline int process_mrelease(int pidfd, unsigned int flags) +{ +#ifdef __NR_process_mrelease + return syscall(__NR_process_mrelease, pidfd, flags); +#else + errno = ENOSYS; + return -1; +#endif +} + +static void write_fault_pages(char *addr, unsigned long nr_pages) +{ + unsigned long i; + + for (i = 0; i < nr_pages; i++) + *((unsigned long *)(addr + (i * PAGE_SIZE))) = i; +} + +static int alloc_noexit(unsigned long nr_pages, int pipefd) +{ + int ppid = getppid(); + void *buf; + + buf = mmap(NULL, nr_pages * PAGE_SIZE, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANON, 0, 0); + if (buf == MAP_FAILED) { + perror("mmap"); + return 1; + } + + write_fault_pages((char *)buf, nr_pages); + + /* Signal the parent that the child is ready */ + if (write(pipefd, "", 1) < 0) { + perror("write"); + return 1; + } + + /* Wait to be killed (when reparenting happens) */ + while (getppid() == ppid) + sleep(1); + + munmap(buf, nr_pages * PAGE_SIZE); + + return 0; +} + + +#define MB(x) (x << 20) +#define MAX_SIZE_MB 1024 + +int main(void) +{ + int res; + int pipefd[2], pidfd; + pid_t pid; + char byte; + size_t size; + int negative_tests_done = 0; + + /* Test a wrong pidfd */ + if (!process_mrelease(-1, 0) || errno != EBADF) { + perror("process_mrelease with wring pidfd"); + exit(1); + } + + /* + * Start the test with 1MB allocation and double every time + * process_mrelease fails + */ + for (size = 1; size <= MAX_SIZE_MB; size *= 2) { + /* + * Pipe for the child to signal when it's done allocating + * memory + */ + if (pipe(pipefd)) { + perror("pipe"); + exit(1); + } + pid = fork(); + if (pid < 0) { + perror("fork"); + exit(1); + } + + if (pid == 0) { + close(pipefd[0]); + res = alloc_noexit(MB(size) / PAGE_SIZE, pipefd[1]); + close(pipefd[1]); + exit(res); + } + + close(pipefd[1]); + /* Block until the child is ready */ + res = read(pipefd[0], &byte, 1); + close(pipefd[0]); + if (res < 0) { + perror("read"); + exit(1); + } + + pidfd = pidfd_open(pid, 0); + if (pidfd < 0) { + perror("pidfd_open"); + exit(1); + } + + /* Run negative tests which require a valid child only once */ + if (!negative_tests_done) { + /* Test invalid flags */ + if (!process_mrelease(pidfd, (unsigned int)-1) || + errno != EINVAL) { + perror("process_mrelease with wrong flags"); + exit(1); + } + /* Test reapling while process is still alive */ + if (!process_mrelease(pidfd, 0) || + errno != EINVAL) { + perror("process_mrelease on a live process"); + exit(1); + } + negative_tests_done = 1; + } + + if (kill(pid, SIGKILL)) { + perror("kill"); + exit(1); + } + + if (!process_mrelease(pidfd, 0)) { + /* Terminate the test once process_mrelease succeeds */ + return 0; + } + + /* + * Ignore the failure if the child exited before mrelease got + * called, increase allocation size and retry the test + */ + if (errno != ESRCH) { + perror("process_mrelease"); + exit(1); + } + + if (waitpid(pid, NULL, 0) < 0) { + perror("waitpid"); + exit(1); + } + close(pidfd); + } + + printf("All process_mrelease attempts failed!\n"); + exit(1); +} diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh index 352ba00cf26b..1986162fea39 100755 --- a/tools/testing/selftests/vm/run_vmtests.sh +++ b/tools/testing/selftests/vm/run_vmtests.sh @@ -287,6 +287,22 @@ else echo "[PASS]" fi
+echo "---------------------" +echo "running mrelease_test" +echo "---------------------" +./mrelease_test +ret_val=$? + +if [ $ret_val -eq 0 ]; then + echo "[PASS]" +elif [ $ret_val -eq $ksft_skip ]; then + echo "[SKIP]" + exitcode=$ksft_skip +else + echo "[FAIL]" + exitcode=1 +fi + echo "-------------------" echo "running mremap_test" echo "-------------------"