[PATCH] drm/ttm: stop passing NULL fence in ttm_bo_move_sync_cleanup
Matthew Auld
matthew.auld at intel.com
Mon Apr 11 10:06:56 UTC 2022
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 at intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>> Cc: Christian König <christian.koenig at amd.com>
>> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>> Cc: Nirmoy Das <nirmoy.das at 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().
>
> Perhaps we need to fix it there.
>
> /Thomas
>
>
>
>> +
>> /**
>> * ttm_bo_pipeline_gutting - purge the contents of a bo
>> * @bo: The buffer object
>> diff --git a/include/drm/ttm/ttm_bo_driver.h
>> b/include/drm/ttm/ttm_bo_driver.h
>> index 059a595e14e5..897b88f0bd59 100644
>> --- a/include/drm/ttm/ttm_bo_driver.h
>> +++ b/include/drm/ttm/ttm_bo_driver.h
>> @@ -245,7 +245,7 @@ int ttm_bo_move_accel_cleanup(struct
>> ttm_buffer_object *bo,
>> struct ttm_resource *new_mem);
>> /**
>> - * ttm_bo_move_accel_cleanup.
>> + * ttm_bo_move_sync_cleanup.
>> *
>> * @bo: A pointer to a struct ttm_buffer_object.
>> * @new_mem: struct ttm_resource indicating where to move.
>> @@ -253,13 +253,8 @@ int ttm_bo_move_accel_cleanup(struct
>> ttm_buffer_object *bo,
>> * Special case of ttm_bo_move_accel_cleanup where the bo is guaranteed
>> * by the caller to be idle. Typically used after memcpy buffer moves.
>> */
>> -static inline void ttm_bo_move_sync_cleanup(struct ttm_buffer_object
>> *bo,
>> - struct ttm_resource *new_mem)
>> -{
>> - int ret = ttm_bo_move_accel_cleanup(bo, NULL, true, false, new_mem);
>> -
>> - WARN_ON(ret);
>> -}
>> +void ttm_bo_move_sync_cleanup(struct ttm_buffer_object *bo,
>> + struct ttm_resource *new_mem);
>> /**
>> * ttm_bo_pipeline_gutting.
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