When igt_random_offset() is a given a range of [0, PAGE_SIZE], it is allowed to return 0. However, attempting to use a size of 0 for the igt_lmem_write_cpu() byte poking, leads to call igt_random_offset() with a range of [offset, offset + 0] and ask it to find a length of 4 within it. This triggers the bug on that the requested length should fit within the range! Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Matthew Auld <matthew.auld@xxxxxxxxx> --- drivers/gpu/drm/i915/selftests/intel_memory_region.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c index 6e80d99048e4..32a199b8df8a 100644 --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c @@ -522,9 +522,10 @@ static int igt_lmem_write_cpu(void *arg) goto out_unpin; } - /* We want to throw in a random width/align */ - bytes[0] = igt_random_offset(&prng, 0, PAGE_SIZE, sizeof(u32), - sizeof(u32)); + /* A random multiple of u32, picked between [64, PAGE_SIZE - 64] */ + bytes[0] = prandom_u32_state(&prng); + bytes[0] = round_up(bytes[0], 64) & (PAGE_SIZE - 1); + GEM_BUG_ON(!IS_ALIGNED(bytes[0], sizeof(u32))); i = 0; do { -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx