I pushed it to my next branch. Mark, Shuah, and others, please let me know if kselftest and KernelCI are better with that. On Fri, Jun 21, 2024 at 08:06:05PM +0200, Mickaël Salaün wrote: > We cannot use CLONE_VFORK because we also need to wait for the timeout > signal. > > Restore tests timeout by using the original fork() call in __run_test() > but also in __TEST_F_IMPL(). Also fix a race condition when waiting for > the test child process. > > Because test metadata are shared between test processes, only the > parent process must set the test PID (child). Otherwise, t->pid may be > set to zero, leading to inconsistent error cases: > > # RUN layout1.rule_on_mountpoint ... > # rule_on_mountpoint: Test ended in some other way [127] > # OK layout1.rule_on_mountpoint > ok 20 layout1.rule_on_mountpoint > > As safeguards, initialize the "status" variable with a valid exit code, > and handle unknown test exits as errors. > > The use of fork() introduces a new race condition in landlock/fs_test.c > which seems to be specific to hostfs bind mounts, but I haven't found > the root cause and it's difficult to trigger. I'll try to fix it with > another patch. > > Cc: Christian Brauner <brauner@xxxxxxxxxx> > Cc: Günther Noack <gnoack@xxxxxxxxxx> > Cc: Jakub Kicinski <kuba@xxxxxxxxxx> > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: Mark Brown <broonie@xxxxxxxxxx> > Cc: Shuah Khan <shuah@xxxxxxxxxx> > Cc: Will Drewry <wad@xxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/r/9341d4db-5e21-418c-bf9e-9ae2da7877e1@xxxxxxxxxxxxx > Fixes: a86f18903db9 ("selftests/harness: Fix interleaved scheduling leading to race conditions") > Fixes: 24cf65a62266 ("selftests/harness: Share _metadata between forked processes") > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx> > Link: https://lore.kernel.org/r/20240621180605.834676-1-mic@xxxxxxxxxxx > --- > tools/testing/selftests/kselftest_harness.h | 43 ++++++++++++--------- > 1 file changed, 24 insertions(+), 19 deletions(-) > > diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h > index b634969cbb6f..40723a6a083f 100644 > --- a/tools/testing/selftests/kselftest_harness.h > +++ b/tools/testing/selftests/kselftest_harness.h > @@ -66,8 +66,6 @@ > #include <sys/wait.h> > #include <unistd.h> > #include <setjmp.h> > -#include <syscall.h> > -#include <linux/sched.h> > > #include "kselftest.h" > > @@ -82,17 +80,6 @@ > # define TH_LOG_ENABLED 1 > #endif > > -/* Wait for the child process to end but without sharing memory mapping. */ > -static inline pid_t clone3_vfork(void) > -{ > - struct clone_args args = { > - .flags = CLONE_VFORK, > - .exit_signal = SIGCHLD, > - }; > - > - return syscall(__NR_clone3, &args, sizeof(args)); > -} > - > /** > * TH_LOG() > * > @@ -437,7 +424,7 @@ static inline pid_t clone3_vfork(void) > } \ > if (setjmp(_metadata->env) == 0) { \ > /* _metadata and potentially self are shared with all forks. */ \ > - child = clone3_vfork(); \ > + child = fork(); \ > if (child == 0) { \ > fixture_name##_setup(_metadata, self, variant->data); \ > /* Let setup failure terminate early. */ \ > @@ -1016,7 +1003,14 @@ void __wait_for_test(struct __test_metadata *t) > .sa_flags = SA_SIGINFO, > }; > struct sigaction saved_action; > - int status; > + /* > + * Sets status so that WIFEXITED(status) returns true and > + * WEXITSTATUS(status) returns KSFT_FAIL. This safe default value > + * should never be evaluated because of the waitpid(2) check and > + * SIGALRM handling. > + */ > + int status = KSFT_FAIL << 8; > + int child; > > if (sigaction(SIGALRM, &action, &saved_action)) { > t->exit_code = KSFT_FAIL; > @@ -1028,7 +1022,15 @@ void __wait_for_test(struct __test_metadata *t) > __active_test = t; > t->timed_out = false; > alarm(t->timeout); > - waitpid(t->pid, &status, 0); > + child = waitpid(t->pid, &status, 0); > + if (child == -1 && errno != EINTR) { > + t->exit_code = KSFT_FAIL; > + fprintf(TH_LOG_STREAM, > + "# %s: Failed to wait for PID %d (errno: %d)\n", > + t->name, t->pid, errno); > + return; > + } > + > alarm(0); > if (sigaction(SIGALRM, &saved_action, NULL)) { > t->exit_code = KSFT_FAIL; > @@ -1083,6 +1085,7 @@ void __wait_for_test(struct __test_metadata *t) > WTERMSIG(status)); > } > } else { > + t->exit_code = KSFT_FAIL; > fprintf(TH_LOG_STREAM, > "# %s: Test ended in some other way [%u]\n", > t->name, > @@ -1218,6 +1221,7 @@ void __run_test(struct __fixture_metadata *f, > struct __test_xfail *xfail; > char test_name[1024]; > const char *diagnostic; > + int child; > > /* reset test struct */ > t->exit_code = KSFT_PASS; > @@ -1236,15 +1240,16 @@ void __run_test(struct __fixture_metadata *f, > fflush(stdout); > fflush(stderr); > > - t->pid = clone3_vfork(); > - if (t->pid < 0) { > + child = fork(); > + if (child < 0) { > ksft_print_msg("ERROR SPAWNING TEST CHILD\n"); > t->exit_code = KSFT_FAIL; > - } else if (t->pid == 0) { > + } else if (child == 0) { > setpgrp(); > t->fn(t, variant); > _exit(t->exit_code); > } else { > + t->pid = child; > __wait_for_test(t); > } > ksft_print_msg(" %4s %s\n", > > base-commit: 83a7eefedc9b56fe7bfeff13b6c7356688ffa670 > -- > 2.45.2 > >
