The crashing_child_sparse() helper touches the first page of the mapping. That forces everything behind it to be a trailing hole. This is easy to handle. Make the test more difficult meaningful by also touchin the last page. This causes the hole to sit between two populated pages.
Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- tools/testing/selftests/coredump/coredump_test_helpers.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/coredump/coredump_test_helpers.c b/tools/testing/selftests/coredump/coredump_test_helpers.c index 45d76fa0f469..89f3954c5607 100644 --- a/tools/testing/selftests/coredump/coredump_test_helpers.c +++ b/tools/testing/selftests/coredump/coredump_test_helpers.c @@ -58,14 +58,16 @@ void crashing_child_sparse(size_t size) char *p; /* - * Touch the first page only. The whole mapping is dumped because - * it has been written to, but all of it save that one page is a - * hole. + * Touch the first and the last page. This will cause the whole mapping + * to be dumped because it has been written to. Everything between + * those two pages is a hole though. */ p = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0); - if (p != MAP_FAILED) + if (p != MAP_FAILED) { p[0] = 'x'; + p[size - 1] = 'x'; + } /* crash on purpose */ *(volatile int *)NULL = 0; -- 2.53.0
