| Message ID | 20210413051721.2896915-6-axelrasmussen@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | userfaultfd: add minor fault handling for shmem | expand |
On Mon, Apr 12, 2021 at 10:17:17PM -0700, Axel Rasmussen wrote: > This is a preparatory commit. In the future, we want to be able to setup > alias mappings for area_src and area_dst in the shmem test, like we do > in the hugetlb_shared test. With a VMA obtained via > mmap(MAP_ANONYMOUS | MAP_SHARED), it isn't clear how to do this. > > So, mmap() with an fd, so we can create alias mappings. Use memfd_create > instead of actually passing in a tmpfs path like hugetlb does, since > it's more convenient / simpler to run, and works just as well. > > Future commits will: > > 1. Setup the alias mappings. > 2. Extend our tests to actually take advantage of this, to test new > userfaultfd behavior being introduced in this series. > > Also, a small fix in the area we're changing: when the hugetlb setup > fails in main(), pass in the right argv[] so we actually print out the > hugetlb file path. > > Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Reviewed-by: Peter Xu <peterx@redhat.com>
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 6339aeaeeff8..fc40831f818f 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -85,6 +85,7 @@ static bool test_uffdio_wp = false; static bool test_uffdio_minor = false; static bool map_shared; +static int shm_fd; static int huge_fd; static char *huge_fd_off0; static unsigned long long *count_verify; @@ -277,8 +278,11 @@ static void shmem_release_pages(char *rel_area) static void shmem_allocate_area(void **alloc_area) { + unsigned long offset = + alloc_area == (void **)&area_src ? 0 : nr_pages * page_size; + *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE, - MAP_ANONYMOUS | MAP_SHARED, -1, 0); + MAP_SHARED, shm_fd, offset); if (*alloc_area == MAP_FAILED) err("mmap of memfd failed"); } @@ -1448,6 +1452,16 @@ int main(int argc, char **argv) err("Open of %s failed", argv[4]); if (ftruncate(huge_fd, 0)) err("ftruncate %s to size 0 failed", argv[4]); + } else if (test_type == TEST_SHMEM) { + shm_fd = memfd_create(argv[0], 0); + if (shm_fd < 0) + err("memfd_create"); + if (ftruncate(shm_fd, nr_pages * page_size * 2)) + err("ftruncate"); + if (fallocate(shm_fd, + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0, + nr_pages * page_size * 2)) + err("fallocate"); } printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n", nr_pages, nr_pages_per_cpu);
This is a preparatory commit. In the future, we want to be able to setup alias mappings for area_src and area_dst in the shmem test, like we do in the hugetlb_shared test. With a VMA obtained via mmap(MAP_ANONYMOUS | MAP_SHARED), it isn't clear how to do this. So, mmap() with an fd, so we can create alias mappings. Use memfd_create instead of actually passing in a tmpfs path like hugetlb does, since it's more convenient / simpler to run, and works just as well. Future commits will: 1. Setup the alias mappings. 2. Extend our tests to actually take advantage of this, to test new userfaultfd behavior being introduced in this series. Also, a small fix in the area we're changing: when the hugetlb setup fails in main(), pass in the right argv[] so we actually print out the hugetlb file path. Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> --- tools/testing/selftests/vm/userfaultfd.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)