Currently unavoidable lockedp loop related to userptr MMU notifier exists in the i915 driver. For that reason, attempts to set up a mmap-offset (or mmap-gtt) mapping to a userptr object may be now preventively rejected by the driver.
A test should exists which checks for that. Would a mapping attempt succeed, the test should trigger the MMU notifier in a way that is proven to result in the lockdep slpat. As that exercise is strictly userptr related, it has been decided to add it as a new subtest to gem_userptr_blits. The new subtest examines userptr interaction with every supported mmap-offset type mapping on top of it. v2: Move the subtest from gem_mmap_offset to gem_userptr_blits, - use dynamic subtests (Chris), - don't FAIL but SKIP on mmap-offset attempt failure (Chris), - on success, try to anger lockdep (Chris). Suggested-by: Chris Wilson <[email protected] Signed-off-by: Janusz Krzysztofik <[email protected]> Cc: Matthew Auld <[email protected]> --- In order to be able to prove the proposed method of angering lockdep actually works, I'm going to submit a kernel patch that reverts commit f6c26b555e14 ("drm/i915: Never allow userptr into the new mapping types") to be tested on Trybot together with this one, so at least non-GTT mmap-offset attempts succeed and the MMU notifier is triggered. Thanks, Janusz tests/i915/gem_userptr_blits.c | 42 ++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/tests/i915/gem_userptr_blits.c b/tests/i915/gem_userptr_blits.c index fcad374ef..5f716a3ea 100644 --- a/tests/i915/gem_userptr_blits.c +++ b/tests/i915/gem_userptr_blits.c @@ -797,6 +797,42 @@ static int test_map_fixed_invalidate(int fd, uint32_t flags) return 0; } +static void test_mmap_offset_invalidate(int fd, const struct mmap_offset *t) +{ + void *ptr, *map; + uint32_t handle; + + /* check if mmap_offset type is supported by hardware, skip if not */ + handle = gem_create(fd, PAGE_SIZE); + map = __gem_mmap_offset(fd, handle, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE, t->type); + igt_require_f(map, + "HW & kernel support for mmap_offset(%s)\n", t->name); + munmap(map, PAGE_SIZE); + gem_close(fd, handle); + + /* create userptr object */ + igt_assert_eq(posix_memalign(&ptr, PAGE_SIZE, PAGE_SIZE), 0); + gem_userptr(fd, ptr, PAGE_SIZE, 0, userptr_flags, &handle); + + /* set up mmap-offset mapping on top of the object, skip if refused */ + map = __gem_mmap_offset(fd, handle, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE, t->type); + igt_skip_on_f(!map && errno == -ENODEV, + "lockdep loop preventive failure possibly occurred\n"); + igt_assert(map); + + /* set object pages in order to activate MMU notifier for it */ + gem_set_domain(fd, handle, t->domain, t->domain); + + /* trigger the notifier */ + munmap(ptr, PAGE_SIZE); + + /* cleanup */ + munmap(map, PAGE_SIZE); + gem_close(fd, handle); +} + static int test_forbidden_ops(int fd) { struct drm_i915_gem_pread gem_pread; @@ -2170,6 +2206,12 @@ igt_main_args("c:", NULL, help_str, opt_handler, NULL) } } + igt_describe("Invalidate pages of userptr with mmap-offset on top"); + igt_subtest_with_dynamic("mmap-offset-invalidate") + for_each_mmap_offset_type(fd, t) + igt_dynamic_f("%s", t->name) + test_mmap_offset_invalidate(fd, t); + igt_subtest("coherency-sync") test_coherency(fd, count); -- 2.21.0 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
