From: Peter Xu <peterx@xxxxxxxxxx> Subject: userfaultfd/selftests: hint the test runner on required privilege Now userfaultfd test program requires either root or ptrace privilege due to the signal/event tests. When UFFDIO_API failed, hint the test runner about this fact verbosely. Link: https://lkml.kernel.org/r/20201208024709.7701-4-peterx@xxxxxxxxxx Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/vm/userfaultfd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/tools/testing/selftests/vm/userfaultfd.c~userfaultfd-selftests-hint-the-test-runner-on-required-privilege +++ a/tools/testing/selftests/vm/userfaultfd.c @@ -794,7 +794,8 @@ static int userfaultfd_open(int features uffdio_api.api = UFFD_API; uffdio_api.features = features; if (ioctl(uffd, UFFDIO_API, &uffdio_api)) { - fprintf(stderr, "UFFDIO_API\n"); + fprintf(stderr, "UFFDIO_API failed.\nPlease make sure to " + "run with either root or ptrace capability.\n"); return 1; } if (uffdio_api.api != UFFD_API) { _
