On 11/8/19 5:35 AM, Koenig, Christian wrote:
> Hi Emily,
>
> exactly that can't happen. See here:
>
>> /* Don't destroy jobs while the timeout worker is running */
>> if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
>> !cancel_delayed_work(&sched->work_tdr))
>> return NULL;
> We never free jobs while the timeout working is running to prevent
> exactly that issue.
I don't think this protects us if drm_sched_cleanup_jobs is called for
scheduler which didn't experience a timeout, in
amdgpu_device_gpu_recover we access sched->ring_mirror_list for all the
schedulers on a device so this condition above won't protect us. What in
fact could help maybe is my recent patch 541c521 drm/sched: Avoid job
cleanup if sched thread is parked. because we do park each of the
scheduler threads during tdr job before trying to access
sched->ring_mirror_list.
Emily - did you see this problem with that patch in place ? I only
pushed it yesterday.
Andrey
>
> Regards,
> Christian.
>
> Am 08.11.19 um 11:32 schrieb Deng, Emily:
>> Hi Christian,
>> The drm_sched_job_timedout-> amdgpu_job_timedout call amdgpu_device_gpu_recover. I mean the main scheduler free the jobs while in amdgpu_device_gpu_recover, and before calling drm_sched_stop.
>>
>> Best wishes
>> Emily Deng
>>
>>
>>
>>> -----Original Message-----
>>> From: Koenig, Christian <Christian.Koenig@xxxxxxx>
>>> Sent: Friday, November 8, 2019 6:26 PM
>>> To: Deng, Emily <Emily.Deng@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>>> Subject: Re: [PATCH] drm/amdgpu: Fix the null pointer issue for tdr
>>>
>>> Hi Emily,
>>>
>>> well who is calling amdgpu_device_gpu_recover() in this case?
>>>
>>> When it's not the scheduler we shouldn't have a guilty job in the first place.
>>>
>>> Regards,
>>> Christian.
>>>
>>> Am 08.11.19 um 11:22 schrieb Deng, Emily:
>>>> Hi Chrisitan,
>>>> No, I am with the new branch and also has the patch. Even it are freed by
>>> main scheduler, how we could avoid main scheduler to free jobs while enter
>>> to function amdgpu_device_gpu_recover?
>>>> Best wishes
>>>> Emily Deng
>>>>
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: Koenig, Christian <Christian.Koenig@xxxxxxx>
>>>>> Sent: Friday, November 8, 2019 6:15 PM
>>>>> To: Deng, Emily <Emily.Deng@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
>>>>> Subject: Re: [PATCH] drm/amdgpu: Fix the null pointer issue for tdr
>>>>>
>>>>> Hi Emily,
>>>>>
>>>>> in this case you are on an old code branch.
>>>>>
>>>>> Jobs are freed now by the main scheduler thread and only if no
>>>>> timeout handler is running.
>>>>>
>>>>> See this patch here:
>>>>>> commit 5918045c4ed492fb5813f980dcf89a90fefd0a4e
>>>>>> Author: Christian König <christian.koenig@xxxxxxx>
>>>>>> Date: Thu Apr 18 11:00:21 2019 -0400
>>>>>>
>>>>>> drm/scheduler: rework job destruction
>>>>> Regards,
>>>>> Christian.
>>>>>
>>>>> Am 08.11.19 um 11:11 schrieb Deng, Emily:
>>>>>> 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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