Hi Christian,
Please refer to follow log, when it enter to amdgpu_device_gpu_recover function, the bad job 000000005086879e is freeing in function amdgpu_job_free_cb at the same time, because of the hardware fence signal. But amdgpu_device_gpu_recover goes faster, at this case, the s_fence is already freed, but job is not freed in time. Then this issue occurs.
[ 449.792189] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring sdma0 timeout, signaled seq=2481, emitted seq=2483
[ 449.793202] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* Process information: process pid 0 thread pid 0, s_job:000000005086879e
[ 449.794163] amdgpu 0000:00:08.0: GPU reset begin!
[ 449.794175] Emily:amdgpu_job_free_cb,Process information: process pid 0 thread pid 0, s_job:000000005086879e
[ 449.794221] Emily:amdgpu_job_free_cb,Process information: process pid 0 thread pid 0, s_job:0000000066eb74ab
[ 449.794222] Emily:amdgpu_job_free_cb,Process information: process pid 0 thread pid 0, s_job:00000000d4438ad9
[ 449.794255] Emily:amdgpu_job_free_cb,Process information: process pid 0 thread pid 0, s_job:00000000b6d69c65
[ 449.794257] Emily:amdgpu_job_free_cb,Process information: process pid 0 thread pid 0, s_job:00000000ea85e922
[ 449.794287] Emily:amdgpu_job_free_cb,Process information: process pid 0 thread pid 0, s_job:00000000ed3a5ac6
[ 449.794366] BUG: unable to handle kernel NULL pointer dereference at 00000000000000c0
[ 449.800818] PGD 0 P4D 0
[ 449.801040] Oops: 0000 [#1] SMP PTI
[ 449.801338] CPU: 3 PID: 55 Comm: kworker/3:1 Tainted: G OE 4.18.0-15-generic #16~18.04.1-Ubuntu
[ 449.802157] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 449.802944] Workqueue: events drm_sched_job_timedout [amd_sched]
[ 449.803488] RIP: 0010:amdgpu_device_gpu_recover+0x1da/0xb60 [amdgpu]
[ 449.804020] Code: dd ff ff 49 39 c5 48 89 55 a8 0f 85 56 ff ff ff 45 85 e4 0f 85 a1 00 00 00 48 8b 45 b0 48 85 c0 0f 84 60 01 00 00 48 8b 40 10 <48> 8b 98 c0 00 00 00 48 85 db 0f 84 4c 01 00 00 48 8b 43 48 a8 01
[ 449.805593] RSP: 0018:ffffb4c7c08f7d68 EFLAGS: 00010286
[ 449.806032] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 449.806625] RDX: ffffb4c7c08f5ac0 RSI: 0000000fffffffe0 RDI: 0000000000000246
[ 449.807224] RBP: ffffb4c7c08f7de0 R08: 00000068b9d54000 R09: 0000000000000000
[ 449.807818] R10: 0000000000000000 R11: 0000000000000148 R12: 0000000000000000
[ 449.808411] R13: ffffb4c7c08f7da0 R14: ffff8d82b8525d40 R15: ffff8d82b8525d40
[ 449.809004] FS: 0000000000000000(0000) GS:ffff8d82bfd80000(0000) knlGS:0000000000000000
[ 449.809674] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 449.810153] CR2: 00000000000000c0 CR3: 000000003cc0a001 CR4: 00000000003606e0
[ 449.810747] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 449.811344] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 449.811937] Call Trace:
[ 449.812206] amdgpu_job_timedout+0x114/0x140 [amdgpu]
[ 449.812635] drm_sched_job_timedout+0x44/0x90 [amd_sched]
[ 449.813139] ? amdgpu_cgs_destroy_device+0x10/0x10 [amdgpu]
[ 449.813609] ? drm_sched_job_timedout+0x44/0x90 [amd_sched]
[ 449.814077] process_one_work+0x1fd/0x3f0
[ 449.814417] worker_thread+0x34/0x410
[ 449.814728] kthread+0x121/0x140
[ 449.815004] ? process_one_work+0x3f0/0x3f0
[ 449.815374] ? kthread_create_worker_on_cpu+0x70/0x70
[ 449.815799] ret_from_fork+0x35/0x40
>-----Original Message-----
>From: Koenig, Christian <Christian.Koenig@xxxxxxx>
>Sent: Friday, November 8, 2019 5:43 PM
>To: Deng, Emily <Emily.Deng@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>Subject: Re: [PATCH] drm/amdgpu: Fix the null pointer issue for tdr
>
>Am 08.11.19 um 10:39 schrieb Deng, Emily:
>> Sorry, please take your time.
>
>Have you seen my other response a bit below?
>
>I can't follow how it would be possible for job->s_fence to be NULL without
>the job also being freed.
>
>So it looks like this patch is just papering over some bigger issues.
>
>Regards,
>Christian.
>
>>
>> Best wishes
>> Emily Deng
>>
>>
>>
>>> -----Original Message-----
>>> From: Koenig, Christian <Christian.Koenig@xxxxxxx>
>>> Sent: Friday, November 8, 2019 5:08 PM
>>> To: Deng, Emily <Emily.Deng@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>>> Subject: Re: [PATCH] drm/amdgpu: Fix the null pointer issue for tdr
>>>
>>> Am 08.11.19 um 09:52 schrieb Deng, Emily:
>>>> Ping.....
>>> You need to give me at least enough time to wake up :)
>>>
>>>>
>>>> Best wishes
>>>> Emily Deng
>>>>
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
>>>>> Deng, Emily
>>>>> Sent: Friday, November 8, 2019 10:56 AM
>>>>> To: Koenig, Christian <Christian.Koenig@xxxxxxx>; amd-
>>>>> gfx@xxxxxxxxxxxxxxxxxxxxx
>>>>> Subject: RE: [PATCH] drm/amdgpu: Fix the null pointer issue for tdr
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
>>>>>> Sent: Thursday, November 7, 2019 7:28 PM
>>>>>> To: Deng, Emily <Emily.Deng@xxxxxxx>;
>>>>>> amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>>>>>> Subject: Re: [PATCH] drm/amdgpu: Fix the null pointer issue for
>>>>>> tdr
>>>>>>
>>>>>> Am 07.11.19 um 11:25 schrieb Emily Deng:
>>>>>>> When the job is already signaled, the s_fence is freed. Then it
>>>>>>> will has null pointer in amdgpu_device_gpu_recover.
>>>>>> NAK, the s_fence is only set to NULL when the job is destroyed.
>>>>>> See drm_sched_job_cleanup().
>>>>> I know it is set to NULL in drm_sched_job_cleanup. But in one case,
>>>>> when it enter into the amdgpu_device_gpu_recover, it already in
>>>>> drm_sched_job_cleanup, and at this time, it will go to free job.
>>>>> But the amdgpu_device_gpu_recover sometimes is faster. At that
>>>>> time, job is not freed, but s_fence is already NULL.
>>> No, that case can't happen. See here:
>>>
>>>> drm_sched_job_cleanup(s_job);
>>>>
>>>> amdgpu_ring_priority_put(ring, s_job->s_priority);
>>>> dma_fence_put(job->fence);
>>>> amdgpu_sync_free(&job->sync);
>>>> amdgpu_sync_free(&job->sched_sync);
>>>> kfree(job);
>>> The job itself is freed up directly after freeing the reference to the s_fence.
>>>
>>> So you are just papering over a much bigger problem here. This patch
>>> is a clear NAK.
>>>
>>> Regards,
>>> Christian.
>>>
>>>>>> When you see a job without an s_fence then that means the problem
>>>>>> is somewhere else.
>>>>>>
>>>>>> Regards,
>>>>>> Christian.
>>>>>>
>>>>>>> Signed-off-by: Emily Deng <Emily.Deng@xxxxxxx>
>>>>>>> ---
>>>>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
>>>>>>> drivers/gpu/drm/scheduler/sched_main.c | 11 ++++++-----
>>>>>>> 2 files changed, 7 insertions(+), 6 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> index e6ce949..5a8f08e 100644
>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>> @@ -4075,7 +4075,7 @@ int amdgpu_device_gpu_recover(struct
>>>>>> amdgpu_device *adev,
>>>>>>> *
>>>>>>> * job->base holds a reference to parent fence
>>>>>>> */
>>>>>>> - if (job && job->base.s_fence->parent &&
>>>>>>> + if (job && job->base.s_fence && job->base.s_fence->parent
>&&
>>>>>>> dma_fence_is_signaled(job->base.s_fence->parent))
>>>>>>> job_signaled = true;
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>> b/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>> index 31809ca..56cc10e 100644
>>>>>>> --- a/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
>>>>>>> @@ -334,8 +334,8 @@ void drm_sched_increase_karma(struct
>>>>>> drm_sched_job
>>>>>>> *bad)
>>>>>>>
>>>>>>> spin_lock(&rq->lock);
>>>>>>> list_for_each_entry_safe(entity, tmp, &rq-
>>entities,
>>>>>> list) {
>>>>>>> - if (bad->s_fence->scheduled.context
>==
>>>>>>> - entity->fence_context) {
>>>>>>> + if (bad->s_fence && (bad->s_fence-
>>>>>>> scheduled.context ==
>>>>>>> + entity->fence_context)) {
>>>>>>> if (atomic_read(&bad-
>>karma) >
>>>>>>> bad->sched->hang_limit)
>>>>>>> if (entity->guilty)
>>>>>>> @@ -376,7 +376,7 @@ void drm_sched_stop(struct
>drm_gpu_scheduler
>>>>>> *sched, struct drm_sched_job *bad)
>>>>>>> * This iteration is thread safe as sched thread is stopped.
>>>>>>> */
>>>>>>> list_for_each_entry_safe_reverse(s_job, tmp, &sched-
>>>>>>> ring_mirror_list, node) {
>>>>>>> - if (s_job->s_fence->parent &&
>>>>>>> + if (s_job->s_fence && s_job->s_fence->parent &&
>>>>>>> dma_fence_remove_callback(s_job->s_fence-
>>parent,
>>>>>>> &s_job->cb)) {
>>>>>>> atomic_dec(&sched->hw_rq_count); @@ -
>395,7
>>>>> +395,8 @@ void
>>>>>>> drm_sched_stop(struct drm_gpu_scheduler
>>>>>> *sched, struct drm_sched_job *bad)
>>>>>>> *
>>>>>>> * Job is still alive so fence refcount at least 1
>>>>>>> */
>>>>>>> - dma_fence_wait(&s_job->s_fence->finished,
>false);
>>>>>>> + if (s_job->s_fence)
>>>>>>> + dma_fence_wait(&s_job->s_fence-
>>finished,
>>>>>> false);
>>>>>>> /*
>>>>>>> * We must keep bad job alive for later use
>during @@
>>>>>> -438,7
>>>>>>> +439,7 @@ void drm_sched_start(struct drm_gpu_scheduler *sched,
>>>>>>> +bool
>>>>>> full_recovery)
>>>>>>> * GPU recovers can't run in parallel.
>>>>>>> */
>>>>>>> list_for_each_entry_safe(s_job, tmp,
>>>>>>> &sched->ring_mirror_list,
>>>>>>> node)
>>>>>> {
>>>>>>> - struct dma_fence *fence = s_job->s_fence->parent;
>>>>>>> + struct dma_fence *fence = s_job->s_fence ? s_job-
>>s_fence-
>>>>>>> parent :
>>>>>>> +NULL;
>>>>>>>
>>>>>>> atomic_inc(&sched->hw_rq_count);
>>>>>>>
>>>>> _______________________________________________
>>>>> amd-gfx mailing list
>>>>> amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>>>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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