create_pagecache_thp_and_fd() fills the backing file for the pagecache THP tests using repeated write() calls, but the return value is never checked.
If a write fails or completes only partially, the test may continue with an incompletely initialized file and produce misleading results. Check the result of write() and fail the test if the expected number of bytes was not written. Signed-off-by: Vineet Agarwal <[email protected]> --- tools/testing/selftests/mm/split_huge_page_test.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 500d07c4938b..eab69b0f59a0 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -609,9 +609,16 @@ static int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, assert(fd_size % sizeof(buf) == 0); for (i = 0; i < sizeof(buf); i++) buf[i] = (unsigned char)i; - for (i = 0; i < fd_size; i += sizeof(buf)) - write(*fd, buf, sizeof(buf)); - + for (i = 0; i < fd_size; i += sizeof(buf)) { + ssize_t written; + + written = write(*fd, buf, sizeof(buf)); + if (written != sizeof(buf)) { + ksft_perror("write testfile"); + close(*fd); + goto err_out_unlink; + } + } close(*fd); sync(); *fd = open("/proc/sys/vm/drop_caches", O_WRONLY); -- 2.54.0
