From 4cbd93c3c110447adc66cb67c08af21f939ae2d7 Mon Sep 17 00:00:00 2001 From: Axel Rasmussen Date: Thu, 27 Jan 2022 13:29:51 -0800 Subject: pidfd: fix test failure due to stack overflow on some arches When running the pidfd_fdinfo_test on arm64, it fails for me. After some digging, the reason is that the child exits due to SIGBUS, because it overflows the 1024 byte stack we've reserved for it. To fix the issue, increase the stack size to 8192 bytes (this number is somewhat arbitrary, and was arrived at through experimentation -- I kept doubling until the failure no longer occurred). Also, let's make the issue easier to debug. wait_for_pid() returns an ambiguous value: it may return -1 in all of these cases: 1. waitpid() itself returned -1 2. waitpid() returned success, but we found !WIFEXITED(status). 3. The child process exited, but it did so with a -1 exit code. There's no way for the caller to tell the difference. So, at least log which occurred, so the test runner can debug things. While debugging this, I found that we had !WIFEXITED(), because the child exited due to a signal. This seems like a reasonably common case, so also print out whether or not we have WIFSIGNALED(), and the associated WTERMSIG() (if any). This lets us see the SIGBUS I'm fixing clearly when it occurs. Finally, I'm suspicious of allocating the child's stack on our stack. man clone(2) suggests that the correct way to do this is with mmap(), and in particular by setting MAP_STACK. So, switch to doing it that way instead. Signed-off-by: Axel Rasmussen Acked-by: Christian Brauner Signed-off-by: Shuah Khan --- tools/testing/selftests/pidfd/pidfd.h | 13 ++++++++++--- tools/testing/selftests/pidfd/pidfd_fdinfo_test.c | 22 ++++++++++++++++++---- 2 files changed, 28 insertions(+), 7 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h index 01f8d3c0cf2c..6922d6417e1c 100644 --- a/tools/testing/selftests/pidfd/pidfd.h +++ b/tools/testing/selftests/pidfd/pidfd.h @@ -68,7 +68,7 @@ #define PIDFD_SKIP 3 #define PIDFD_XFAIL 4 -int wait_for_pid(pid_t pid) +static inline int wait_for_pid(pid_t pid) { int status, ret; @@ -78,13 +78,20 @@ again: if (errno == EINTR) goto again; + ksft_print_msg("waitpid returned -1, errno=%d\n", errno); return -1; } - if (!WIFEXITED(status)) + if (!WIFEXITED(status)) { + ksft_print_msg( + "waitpid !WIFEXITED, WIFSIGNALED=%d, WTERMSIG=%d\n", + WIFSIGNALED(status), WTERMSIG(status)); return -1; + } - return WEXITSTATUS(status); + ret = WEXITSTATUS(status); + ksft_print_msg("waitpid WEXITSTATUS=%d\n", ret); + return ret; } static inline int sys_pidfd_open(pid_t pid, unsigned int flags) diff --git a/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c b/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c index 22558524f71c..3fd8e903118f 100644 --- a/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c +++ b/tools/testing/selftests/pidfd/pidfd_fdinfo_test.c @@ -12,6 +12,7 @@ #include #include #include +#include #include "pidfd.h" #include "../kselftest.h" @@ -80,7 +81,10 @@ static inline int error_check(struct error *err, const char *test_name) return err->code; } +#define CHILD_STACK_SIZE 8192 + struct child { + char *stack; pid_t pid; int fd; }; @@ -89,17 +93,22 @@ static struct child clone_newns(int (*fn)(void *), void *args, struct error *err) { static int flags = CLONE_PIDFD | CLONE_NEWPID | CLONE_NEWNS | SIGCHLD; - size_t stack_size = 1024; - char *stack[1024] = { 0 }; struct child ret; if (!(flags & CLONE_NEWUSER) && geteuid() != 0) flags |= CLONE_NEWUSER; + ret.stack = mmap(NULL, CHILD_STACK_SIZE, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0); + if (ret.stack == MAP_FAILED) { + error_set(err, -1, "mmap of stack failed (errno %d)", errno); + return ret; + } + #ifdef __ia64__ - ret.pid = __clone2(fn, stack, stack_size, flags, args, &ret.fd); + ret.pid = __clone2(fn, ret.stack, CHILD_STACK_SIZE, flags, args, &ret.fd); #else - ret.pid = clone(fn, stack + stack_size, flags, args, &ret.fd); + ret.pid = clone(fn, ret.stack + CHILD_STACK_SIZE, flags, args, &ret.fd); #endif if (ret.pid < 0) { @@ -129,6 +138,11 @@ static inline int child_join(struct child *child, struct error *err) else if (r > 0) error_set(err, r, "child %d reported: %d", child->pid, r); + if (munmap(child->stack, CHILD_STACK_SIZE)) { + error_set(err, -1, "munmap of child stack failed (errno %d)", errno); + r = -1; + } + return r; } -- cgit v1.2.3 From e2aa5e650b07693477dff554053605976789fd68 Mon Sep 17 00:00:00 2001 From: Axel Rasmussen Date: Thu, 27 Jan 2022 14:11:15 -0800 Subject: selftests: fixup build warnings in pidfd / clone3 tests These are some trivial fixups, which were needed to build the tests with clang and -Werror. The following issues are fixed: - Remove various unused variables. - In child_poll_leader_exit_test, clang isn't smart enough to realize syscall(SYS_exit, 0) won't return, so it complains we never return from a non-void function. Add an extra exit(0) to appease it. - In test_pidfd_poll_leader_exit, ret may be branched on despite being uninitialized, if we have !use_waitpid. Initialize it to zero to get the right behavior in that case. Signed-off-by: Axel Rasmussen Acked-by: Christian Brauner Signed-off-by: Shuah Khan --- tools/testing/selftests/clone3/clone3.c | 2 -- tools/testing/selftests/pidfd/pidfd_test.c | 6 +++--- tools/testing/selftests/pidfd/pidfd_wait.c | 5 ++--- 3 files changed, 5 insertions(+), 8 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c index 076cf4325f78..cd4582129c7d 100644 --- a/tools/testing/selftests/clone3/clone3.c +++ b/tools/testing/selftests/clone3/clone3.c @@ -126,8 +126,6 @@ static void test_clone3(uint64_t flags, size_t size, int expected, int main(int argc, char *argv[]) { - pid_t pid; - uid_t uid = getuid(); ksft_print_header(); diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c index 529eb700ac26..9a2d64901d59 100644 --- a/tools/testing/selftests/pidfd/pidfd_test.c +++ b/tools/testing/selftests/pidfd/pidfd_test.c @@ -441,7 +441,6 @@ static void test_pidfd_poll_exec(int use_waitpid) { int pid, pidfd = 0; int status, ret; - pthread_t t1; time_t prog_start = time(NULL); const char *test_name = "pidfd_poll check for premature notification on child thread exec"; @@ -500,13 +499,14 @@ static int child_poll_leader_exit_test(void *args) */ *child_exit_secs = time(NULL); syscall(SYS_exit, 0); + /* Never reached, but appeases compiler thinking we should return. */ + exit(0); } static void test_pidfd_poll_leader_exit(int use_waitpid) { int pid, pidfd = 0; - int status, ret; - time_t prog_start = time(NULL); + int status, ret = 0; const char *test_name = "pidfd_poll check for premature notification on non-empty" "group leader exit"; diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c index be2943f072f6..17999e082aa7 100644 --- a/tools/testing/selftests/pidfd/pidfd_wait.c +++ b/tools/testing/selftests/pidfd/pidfd_wait.c @@ -39,7 +39,7 @@ static int sys_waitid(int which, pid_t pid, siginfo_t *info, int options, TEST(wait_simple) { - int pidfd = -1, status = 0; + int pidfd = -1; pid_t parent_tid = -1; struct clone_args args = { .parent_tid = ptr_to_u64(&parent_tid), @@ -47,7 +47,6 @@ TEST(wait_simple) .flags = CLONE_PIDFD | CLONE_PARENT_SETTID, .exit_signal = SIGCHLD, }; - int ret; pid_t pid; siginfo_t info = { .si_signo = 0, @@ -88,7 +87,7 @@ TEST(wait_simple) TEST(wait_states) { - int pidfd = -1, status = 0; + int pidfd = -1; pid_t parent_tid = -1; struct clone_args args = { .parent_tid = ptr_to_u64(&parent_tid), -- cgit v1.2.3 From 183f80fd72db42c9cc483aa7a5e8e881355d0b03 Mon Sep 17 00:00:00 2001 From: Sean Young Date: Tue, 1 Feb 2022 18:38:36 +0000 Subject: selftests/ir: fix build with ancient kernel headers Since commit e2bcbd7769ee ("tools headers UAPI: remove stale lirc.h"), the build of the selftests fails on rhel 8 since its version of /usr/include/linux/lirc.h has no definition of RC_PROTO_RCMM32, etc [1]. [1] https://lkml.org/lkml/2022/1/28/275 Fixes: e2bcbd7769ee ("tools headers UAPI: remove stale lirc.h") Reviewed-by: Shuah Khan Reported-by: kernel test robot Signed-off-by: Sean Young Signed-off-by: Shuah Khan --- tools/testing/selftests/ir/ir_loopback.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'tools/testing') diff --git a/tools/testing/selftests/ir/ir_loopback.c b/tools/testing/selftests/ir/ir_loopback.c index 06256c96df12..f4a15cbdd5ea 100644 --- a/tools/testing/selftests/ir/ir_loopback.c +++ b/tools/testing/selftests/ir/ir_loopback.c @@ -29,6 +29,16 @@ #define SYSFS_PATH_MAX 256 #define DNAME_PATH_MAX 256 +/* + * Support ancient lirc.h which does not have these values. Can be removed + * once RHEL 8 is no longer a relevant testing platform. + */ +#if RC_PROTO_MAX < 26 +#define RC_PROTO_RCMM12 24 +#define RC_PROTO_RCMM24 25 +#define RC_PROTO_RCMM32 26 +#endif + static const struct { enum rc_proto proto; const char *name; -- cgit v1.2.3