On 4/11/22 12:06, Matthew Auld wrote:
On 11/04/2022 10:56, Thomas Hellström wrote:
Hi, Matthew
On 4/11/22 10:56, Matthew Auld wrote:
If we hit the sync case, like when skipping clearing for kernel internal objects, or when falling back to cpu clearing, like in i915, we end up trying to add a NULL fence, but with some recent changes in this area this now just results in NULL deref in dma_resv_add_fence:
<1>[ 5.466383] BUG: kernel NULL pointer dereference, address: 0000000000000008 <1>[ 5.466384] #PF: supervisor read access in kernel mode <1>[ 5.466385] #PF: error_code(0x0000) - not-present page <6>[ 5.466386] PGD 0 P4D 0 <4>[ 5.466387] Oops: 0000 [#1] PREEMPT SMP NOPTI <4>[ 5.466389] CPU: 5 PID: 267 Comm: modprobe Not tainted 5.18.0-rc2-CI-CI_DRM_11481+ #1 <4>[ 5.466391] RIP: 0010:dma_resv_add_fence+0x63/0x260 <4>[ 5.466395] Code: 38 85 c0 0f 84 df 01 00 00 0f 88 e8 01 00 00 83 c0 01 0f 88 df 01 00 00 8b 05 35 89 10 01 49 8d 5e 68 85 c0 0f 85 45 01 00 00 <48> 8b 45 08 48 3d c0 a5 0a 82 0f 84 5c 01 00 00 48 3d 60 a5 0a 82 <4>[ 5.466396] RSP: 0018:ffffc90000e974f8 EFLAGS: 00010202 <4>[ 5.466397] RAX: 0000000000000001 RBX: ffff888123e88b28 RCX: 00000000ffffffff <4>[ 5.466398] RDX: 0000000000000001 RSI: ffffffff822e4f50 RDI: ffffffff8233f087 <4>[ 5.466399] RBP: 0000000000000000 R08: ffff8881313dbc80 R09: 0000000000000001 <4>[ 5.466399] R10: 0000000000000001 R11: 00000000da354294 R12: 0000000000000000 <4>[ 5.466400] R13: ffff88810927dc58 R14: ffff888123e88ac0 R15: ffff88810a88d600 <4>[ 5.466401] FS: 00007f5fa1193540(0000) GS:ffff88845d880000(0000) knlGS:0000000000000000 <4>[ 5.466402] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4>[ 5.466402] CR2: 0000000000000008 CR3: 0000000106dd6003 CR4: 00000000003706e0 <4>[ 5.466403] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 <4>[ 5.466404] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 <4>[ 5.466404] Call Trace: <4>[ 5.466405] <TASK> <4>[ 5.466406] ttm_bo_move_accel_cleanup+0x62/0x270 [ttm] <4>[ 5.466411] ? i915_rsgt_from_buddy_resource+0x185/0x1e0 [i915] <4>[ 5.466529] i915_ttm_move+0xfd/0x430 [i915] <4>[ 5.466833] ? dma_resv_reserve_fences+0x4e/0x320 <4>[ 5.466836] ? ttm_bo_add_move_fence.constprop.20+0xf7/0x140 [ttm] <4>[ 5.466841] ttm_bo_handle_move_mem+0xa1/0x140 [ttm] <4>[ 5.466845] ttm_bo_validate+0xee/0x160 [ttm] <4>[ 5.466849] __i915_ttm_get_pages+0x4f/0x210 [i915] <4>[ 5.466976] i915_ttm_get_pages+0xad/0x140 [i915] <4>[ 5.467094] ____i915_gem_object_get_pages+0x32/0xf0 [i915] <4>[ 5.467210] __i915_gem_object_get_pages+0x89/0xa0 [i915] <4>[ 5.467323] i915_vma_get_pages+0x114/0x1d0 [i915] <4>[ 5.467446] i915_vma_pin_ww+0xd3/0xa90 [i915] <4>[ 5.467570] i915_vma_pin.constprop.10+0x119/0x1b0 [i915] <4>[ 5.467700] ? __mutex_unlock_slowpath+0x3e/0x2b0 <4>[ 5.467704] intel_alloc_initial_plane_obj.isra.6+0x1a9/0x390 [i915] <4>[ 5.467833] intel_crtc_initial_plane_config+0x83/0x340 [i915]
In the ttm_bo_move_sync_cleanup() case it seems we only really care about calling ttm_bo_wait_free_node(), so let's instead just call that directly.
Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com Cc: Christian König christian.koenig@amd.com Cc: Lucas De Marchi lucas.demarchi@intel.com Cc: Nirmoy Das nirmoy.das@linux.intel.com
drivers/gpu/drm/ttm/ttm_bo_util.c | 15 +++++++++++++++ include/drm/ttm/ttm_bo_driver.h | 11 +++-------- 2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index bc5190340b9c..1cbfb00c1d65 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -572,6 +572,21 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo, } EXPORT_SYMBOL(ttm_bo_move_accel_cleanup); +void ttm_bo_move_sync_cleanup(struct ttm_buffer_object *bo, + struct ttm_resource *new_mem) +{ + struct ttm_device *bdev = bo->bdev; + struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type); + int ret;
+ ret = ttm_bo_wait_free_node(bo, man->use_tt); + if (WARN_ON(ret)) + return;
+ ttm_bo_assign_mem(bo, new_mem); +} +EXPORT_SYMBOL(ttm_bo_move_sync_cleanup);
I don't think this will help in the case where we call ttm_bo_move_accel_cleanup() with a NULL fence....
Hmm, do you know if that case actually exists? I thought the only current user passing fence == NULL was ttm_bo_move_sync_cleanup().
Yes, indeed, you're right. Not sure if any other driver hits that, though.
/Thomas