On Sun, Oct 08, 2023 at 11:42:28PM -0700, Suren Baghdasaryan wrote:
> Add a test for new UFFDIO_MOVE ioctl which uses uffd to move source
> into destination buffer while checking the contents of both after
> remapping. After the operation the content of the destination buffer
> should match the original source buffer's content while the source
> buffer should be zeroed.
>
> Signed-off-by: Suren Baghdasaryan <sur...@google.com>
> ---
> tools/testing/selftests/mm/uffd-common.c | 41 ++++++++++++-
> tools/testing/selftests/mm/uffd-common.h | 1 +
> tools/testing/selftests/mm/uffd-unit-tests.c | 62 ++++++++++++++++++++
> 3 files changed, 102 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/uffd-common.c
> b/tools/testing/selftests/mm/uffd-common.c
> index 02b89860e193..ecc1244f1c2b 100644
> --- a/tools/testing/selftests/mm/uffd-common.c
> +++ b/tools/testing/selftests/mm/uffd-common.c
> @@ -52,6 +52,13 @@ static int anon_allocate_area(void **alloc_area, bool
> is_src)
> *alloc_area = NULL;
> return -errno;
> }
> +
> + /* Prevent source pages from collapsing into THPs */
> + if (madvise(*alloc_area, nr_pages * page_size, MADV_NOHUGEPAGE)) {
> + *alloc_area = NULL;
> + return -errno;
> + }
Can we move this to test specific code?
> +
> return 0;
> }
>
> @@ -484,8 +491,14 @@ void uffd_handle_page_fault(struct uffd_msg *msg, struct
> uffd_args *args)
> offset = (char *)(unsigned long)msg->arg.pagefault.address -
> area_dst;
> offset &= ~(page_size-1);
>
> - if (copy_page(uffd, offset, args->apply_wp))
> - args->missing_faults++;
> + /* UFFD_MOVE is supported for anon non-shared mappings. */
> + if (uffd_test_ops == &anon_uffd_test_ops && !map_shared) {
IIUC this means move_page() will start to run on many other tests... as
long as anonymous & private. Probably not wanted, because not all tests
may need this MOVE test, and it also means UFFDIO_COPY is never tested on
anonymous..
You can overwrite uffd_args.handle_fault(). Axel just added a hook which
seems also usable here. See 99aa77215ad02.
> + if (move_page(uffd, offset))
> + args->missing_faults++;
> + } else {
> + if (copy_page(uffd, offset, args->apply_wp))
> + args->missing_faults++;
> + }
> }
> }
>
> @@ -620,6 +633,30 @@ int copy_page(int ufd, unsigned long offset, bool wp)
> return __copy_page(ufd, offset, false, wp);
> }
>
> +int move_page(int ufd, unsigned long offset)
> +{
> + struct uffdio_move uffdio_move;
> +
> + if (offset >= nr_pages * page_size)
> + err("unexpected offset %lu\n", offset);
> + uffdio_move.dst = (unsigned long) area_dst + offset;
> + uffdio_move.src = (unsigned long) area_src + offset;
> + uffdio_move.len = page_size;
> + uffdio_move.mode = UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES;
> + uffdio_move.move = 0;
> + if (ioctl(ufd, UFFDIO_MOVE, &uffdio_move)) {
> + /* real retval in uffdio_move.move */
> + if (uffdio_move.move != -EEXIST)
> + err("UFFDIO_MOVE error: %"PRId64,
> + (int64_t)uffdio_move.move);
> + wake_range(ufd, uffdio_move.dst, page_size);
> + } else if (uffdio_move.move != page_size) {
> + err("UFFDIO_MOVE error: %"PRId64, (int64_t)uffdio_move.move);
> + } else
> + return 1;
> + return 0;
> +}
> +
> int uffd_open_dev(unsigned int flags)
> {
> int fd, uffd;
> diff --git a/tools/testing/selftests/mm/uffd-common.h
> b/tools/testing/selftests/mm/uffd-common.h
> index 7c4fa964c3b0..f4d79e169a3d 100644
> --- a/tools/testing/selftests/mm/uffd-common.h
> +++ b/tools/testing/selftests/mm/uffd-common.h
> @@ -111,6 +111,7 @@ void wp_range(int ufd, __u64 start, __u64 len, bool wp);
> void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_args *args);
> int __copy_page(int ufd, unsigned long offset, bool retry, bool wp);
> int copy_page(int ufd, unsigned long offset, bool wp);
> +int move_page(int ufd, unsigned long offset);
> void *uffd_poll_thread(void *arg);
>
> int uffd_open_dev(unsigned int flags);
> diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c
> b/tools/testing/selftests/mm/uffd-unit-tests.c
> index 2709a34a39c5..f0ded3b34367 100644
> --- a/tools/testing/selftests/mm/uffd-unit-tests.c
> +++ b/tools/testing/selftests/mm/uffd-unit-tests.c
> @@ -824,6 +824,10 @@ static void uffd_events_test_common(bool wp)
> char c;
> struct uffd_args args = { 0 };
>
> + /* Prevent source pages from being mapped more than once */
> + if (madvise(area_src, nr_pages * page_size, MADV_DONTFORK))
> + err("madvise(MADV_DONTFORK) failed");
Modifying events test is weird.. I assume you don't need this anymore after
you switch to the handle_fault() hook.
> +
> fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
> if (uffd_register(uffd, area_dst, nr_pages * page_size,
> true, wp, false))
> @@ -1062,6 +1066,58 @@ static void uffd_poison_test(uffd_test_args_t *targs)
> uffd_test_pass();
> }
>
> +static void uffd_move_test(uffd_test_args_t *targs)
> +{
> + unsigned long nr;
> + pthread_t uffd_mon;
> + char c;
> + unsigned long long count;
> + struct uffd_args args = { 0 };
> +
> + if (uffd_register(uffd, area_dst, nr_pages * page_size,
> + true, false, false))
> + err("register failure");
> +
> + if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
> + err("uffd_poll_thread create");
> +
> + /*
> + * Read each of the pages back using the UFFD-registered mapping. We
> + * expect that the first time we touch a page, it will result in a
> missing
> + * fault. uffd_poll_thread will resolve the fault by remapping source
> + * page to destination.
> + */
> + for (nr = 0; nr < nr_pages; nr++) {
> + /* Check area_src content */
> + count = *area_count(area_src, nr);
> + if (count != count_verify[nr])
> + err("nr %lu source memory invalid %llu %llu\n",
> + nr, count, count_verify[nr]);
> +
> + /* Faulting into area_dst should remap the page */
> + count = *area_count(area_dst, nr);
> + if (count != count_verify[nr])
> + err("nr %lu memory corruption %llu %llu\n",
> + nr, count, count_verify[nr]);
> +
> + /* Re-check area_src content which should be empty */
> + count = *area_count(area_src, nr);
> + if (count != 0)
> + err("nr %lu move failed %llu %llu\n",
> + nr, count, count_verify[nr]);
All of above should see zeros, right? Because I don't think anyone boosted
the counter at all..
Maybe set some non-zero values to it? Then the re-check can make more
sense.
If you want, I think we can also make uffd-stress.c test to cover MOVE too,
basically replacing all UFFDIO_COPY when e.g. user specified from cmdline.
Optional, and may need some touch ups here and there, though.
Thanks,
> + }
> +
> + if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
> + err("pipe write");
> + if (pthread_join(uffd_mon, NULL))
> + err("join() failed");
> +
> + if (args.missing_faults != nr_pages || args.minor_faults != 0)
> + uffd_test_fail("stats check error");
> + else
> + uffd_test_pass();
> +}
> +
> /*
> * Test the returned uffdio_register.ioctls with different register modes.
> * Note that _UFFDIO_ZEROPAGE is tested separately in the zeropage test.
> @@ -1139,6 +1195,12 @@ uffd_test_case_t uffd_tests[] = {
> .mem_targets = MEM_ALL,
> .uffd_feature_required = 0,
> },
> + {
> + .name = "move",
> + .uffd_fn = uffd_move_test,
> + .mem_targets = MEM_ANON,
> + .uffd_feature_required = UFFD_FEATURE_MOVE,
> + },
> {
> .name = "wp-fork",
> .uffd_fn = uffd_wp_fork_test,
> --
> 2.42.0.609.gbb76f46606-goog
>
--
Peter Xu
