Hi,
we've received a regression report showing NULL dereference Oops with radeon driver on 5.12 kernel: https://bugzilla.opensuse.org/show_bug.cgi?id=1185516
It turned out that the recent TTM cleanup / refactoring via commit 0575ff3d33cd ("drm/radeon: stop using pages with drm_prime_sg_to_page_addr_arrays v2") is the culprit. On 5.12 kernel, ttm->pages is no longer allocated / set up, while the radeon driver still has a few places assuming the valid ttm->pages, and for the reporter (running the modesettig driver), radeon_gart_bind() hits the problem.
A hackish patch below was confirmed to work, at least, but obviously we need a proper fix.
Could you take a look at it?
thanks,
Takashi
--- a/drivers/gpu/drm/radeon/radeon_gart.c +++ b/drivers/gpu/drm/radeon/radeon_gart.c @@ -253,7 +253,7 @@ void radeon_gart_unbind(struct radeon_de t = offset / RADEON_GPU_PAGE_SIZE; p = t / (PAGE_SIZE / RADEON_GPU_PAGE_SIZE); for (i = 0; i < pages; i++, p++) { - if (rdev->gart.pages[p]) { + if (1 /*rdev->gart.pages[p]*/) { rdev->gart.pages[p] = NULL; for (j = 0; j < (PAGE_SIZE / RADEON_GPU_PAGE_SIZE); j++, t++) { rdev->gart.pages_entry[t] = rdev->dummy_page.entry; @@ -301,7 +301,7 @@ int radeon_gart_bind(struct radeon_devic p = t / (PAGE_SIZE / RADEON_GPU_PAGE_SIZE);
for (i = 0; i < pages; i++, p++) { - rdev->gart.pages[p] = pagelist[i]; + /* rdev->gart.pages[p] = pagelist[i]; */ page_base = dma_addr[i]; for (j = 0; j < (PAGE_SIZE / RADEON_GPU_PAGE_SIZE); j++, t++) { page_entry = radeon_gart_get_page_entry(page_base, flags); --- a/drivers/gpu/drm/radeon/radeon_ttm.c +++ b/drivers/gpu/drm/radeon/radeon_ttm.c @@ -360,6 +360,8 @@ static int radeon_ttm_tt_pin_userptr(str
if (current->mm != gtt->usermm) return -EPERM; + if (!ttm->pages) + return -EPERM;
if (gtt->userflags & RADEON_GEM_USERPTR_ANONONLY) { /* check that we only pin down anonymous memory