It depends on what you mean by "handle". If amdgpu_cs_submit_raw were to
return ECANCELED, the correct error message would be printed.
We don't do any of the "trying to continue" business because back when
we last discussed that we said that it wasn't such a great idea, and to
be honest, it really isn't a great idea for normal applications. For the
X server / compositor it could be valuable though.
Cheers,
Nicolai
On 09.10.2017 15:57, Olsak, Marek wrote:
> Mesa does not handle -ECANCELED. It only returns -ECANCELED from the
> Mesa winsys layer if the CS ioctl wasn't called (because the context is
> already lost and so the winsys doesn't submit further CS ioctls).
>
>
> When the CS ioctl fails for the first time, the kernel error is returned
> and the context is marked as "lost".
>
> The next command submission is automatically dropped by the winsys and
> it returns -ECANCELED.
>
>
> Marek
>
> ------------------------------------------------------------------------
> *From:* Haehnle, Nicolai
> *Sent:* Monday, October 9, 2017 2:58:02 PM
> *To:* Koenig, Christian; Liu, Monk; Nicolai Hähnle;
> amd-gfx at lists.freedesktop.org; Olsak, Marek
> *Cc:* Li, Bingley
> *Subject:* Re: [PATCH 5/5] drm/amd/sched: signal and free remaining
> fences in amd_sched_entity_fini
> On 09.10.2017 14:33, Christian König wrote:
>> Am 09.10.2017 um 13:27 schrieb Nicolai Hähnle:
>>> On 09.10.2017 13:12, Christian König wrote:
>>>>>
>>>>>> Nicolai, how hard would it be to handle ENODEV as failure for all
>>>>>> currently existing contexts?
>>>>>
>>>>> Impossible? "All currently existing contexts" is not a well-defined
>>>>> concept when multiple drivers co-exist in the same process.
>>>>
>>>> Ok, let me refine the question: I assume there are resources "shared"
>>>> between contexts like binary shader code for example which needs to
>>>> be reuploaded when VRAM is lost.
>>>>
>>>> How hard would it be to handle that correctly?
>>>
>>> Okay, that makes more sense :)
>>>
>>> With the current interface it's still pretty difficult, but if we
>>> could get a new per-device query ioctl which returns a "VRAM loss
>>> counter", it would be reasonably straight-forward.
>>
>> The problem with the VRAM lost counter is that this isn't save either.
>> E.g. you could have an application which uploads shaders, a GPU reset
>> happens and VRAM is lost and then the application creates a new context
>> and makes submission with broken shader binaries.
>
> Hmm. Here's how I imagined we'd be using a VRAM lost counter:
>
> int si_shader_binary_upload(...)
> {
> Â Â Â ...
> Â Â Â shader->bo_vram_lost_counter = sscreen->vram_lost_counter;
> Â Â Â shader->bo = pipe_buffer_create(...);
> Â Â Â ptr = sscreen->b.ws->buffer_map(shader->bo->buf, ...);
> Â Â Â ... copies ...
> Â Â Â sscreen->b.ws->buffer_unmap(shader->bo->buf);
> }
>
> int si_shader_select(...)
> {
> Â Â Â ...
> Â Â Â r = si_shader_select_with_key(ctx->sscreen, state, ...);
> Â Â Â if (r) return r;
>
> Â Â Â if (state->current->bo_vram_lost_counter !=
> Â Â Â Â Â Â Â ctx->sscreen->vram_lost_counter) {
> Â Â Â Â Â Â ... re-upload sequence ...
> Â Â Â }
> }
>
> (Not shown: logic that compares ctx->vram_lost_counter with
> sscreen->vram_lost_counter and forces a re-validation of all state
> including shaders.)
>
> That should cover this scenario, shouldn't it?
>
> Oh... I see one problem. But it should be easy to fix: when creating a
> new amdgpu context, Mesa needs to query the vram lost counter. So then
> the sequence of events would be either:
>
> - VRAM lost counter starts at 0
> - Mesa uploads a shader binary
> - Unrelated GPU reset happens, kernel increments VRAM lost counter to 1
> - Mesa creates a new amdgpu context, queries the VRAM lost counter --> 1
> - si_screen::vram_lost_counter is updated to 1
> - Draw happens on the new context --> si_shader_select will catch the
> VRAM loss
>
> Or:
>
> - VRAM lost counter starts at 0
> - Mesa uploads a shader binary
> - Mesa creates a new amdgpu context, VRAM lost counter still 0
> - Unrelated GPU reset happens, kernel increments VRAM lost counter to 1
> - Draw happens on the new context and proceeds normally
> ...
> - Mesa flushes the CS, and the kernel will return an error code because
> the device VRAM lost counter is different from the amdgpu context VRAM
> lost counter
>
>
>> So I would still vote for a separate IOCTL to reset the VRAM lost state
>> which is called *before" user space starts to reupload
>> shader/descriptors etc...
>
> The question is: is that separate IOCTL per-context or per-fd? If it's
> per-fd, then it's not compatible with multiple drivers. If it's
> per-context, then I don't see how it helps. Perhaps you could explain?
>
>
> Â > This way you also catch the case when another reset happens while you
> Â > re-upload things.
>
> My assumption would be that the re-upload happens *after* the new amdgpu
> context is created. Then the repeat reset should be caught by the kernel
> when we try to submit a CS on the new context (this is assuming that the
> kernel context's vram lost counter is initialized properly when the
> context is created):
>
> - Mesa prepares upload, sets shader->bo_vram_lost_counter to 0
> - Mesa uploads a shader binary
> - While doing this, a GPU reset happens[0], kernel increments device
> VRAM lost counter to 1
> - Draw happens with the new shader, Mesa proceeds normally
> ...
> - On flush / CS submit, the kernel detects the VRAM lost state and
> returns an error to Mesa
>
> [0] Out of curiosity: What happens on the CPU side if the PCI / full
> ASIC reset method is used? Is there a time window where we could get a SEGV?
>
>
> [snip]
>>> BTW, I still don't like ENODEV. It seems more like the kind of error
>>> code you'd return with hot-pluggable GPUs where the device can
>>> physically disappear...
>>
>> Yeah, ECANCELED sounds like a better alternative. But I think we should
>> still somehow note the fatality of loosing VRAM to userspace.
>>
>> How about ENODATA or EBADFD?
>
> According to the manpage, EBADFD is "File descriptor in bad state.".
> Sounds fitting :)
>
> Cheers,
> Nicolai
>
>
>>
>> Regards,
>> Christian.
>>
>>>
>>> Cheers,
>>> Nicolai
>>>
>>>
>>>>
>>>> Regards,
>>>> Christian.
>>>>
>>>> Am 09.10.2017 um 13:04 schrieb Nicolai Hähnle:
>>>>> On 09.10.2017 12:59, Christian König wrote:
>>>>>> Nicolai, how hard would it be to handle ENODEV as failure for all
>>>>>> currently existing contexts?
>>>>>
>>>>> Impossible? "All currently existing contexts" is not a well-defined
>>>>> concept when multiple drivers co-exist in the same process.
>>>>>
>>>>> And what would be the purpose of this? If it's to support VRAM loss,
>>>>> having a per-context VRAM loss counter would enable each context to
>>>>> signal ECANCELED separately.
>>>>>
>>>>> Cheers,
>>>>> Nicolai
>>>>>
>>>>>
>>>>>>
>>>>>> Monk, would it be ok with you when we return ENODEV only for
>>>>>> existing context when VRAM is lost and/or we have a strict mode GPU
>>>>>> reset? E.g. newly created contexts would continue work as they should.
>>>>>>
>>>>>> Regards,
>>>>>> Christian.
>>>>>>
>>>>>> Am 09.10.2017 um 12:49 schrieb Nicolai Hähnle:
>>>>>>> Hi Monk,
>>>>>>>
>>>>>>> Yes, you're right, we're only using ECANCELED internally. But as a
>>>>>>> consequence, Mesa would already handle a kernel error of ECANCELED
>>>>>>> on context loss correctly :)
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Nicolai
>>>>>>>
>>>>>>> On 09.10.2017 12:35, Liu, Monk wrote:
>>>>>>>> Hi Christian
>>>>>>>>
>>>>>>>> You reject some of my patches that returns -ENODEV, with the
>>>>>>>> cause that MESA doesn't do the handling on -ENODEV
>>>>>>>>
>>>>>>>> But if Nicolai can confirm that MESA do have a handling on
>>>>>>>> -ECANCELED, then we need to overall align our error code, on
>>>>>>>> detail below IOCTL can return error code:
>>>>>>>>
>>>>>>>> Amdgpu_cs_ioctl
>>>>>>>> Amdgpu_cs_wait_ioctl
>>>>>>>> Amdgpu_cs_wait_fences_ioctl
>>>>>>>> Amdgpu_info_ioctl
>>>>>>>>
>>>>>>>>
>>>>>>>> My patches is:
>>>>>>>> return -ENODEV on cs_ioctl if the context is detected guilty,
>>>>>>>> also return -ENODEV on cs_wait|cs_wait_fences if the fence is
>>>>>>>> signaled but with error -ETIME,
>>>>>>>> also return -ENODEV on info_ioctl so UMD can query if gpu reset
>>>>>>>> happened after the process created (because for strict mode we
>>>>>>>> block process instead of context)
>>>>>>>>
>>>>>>>>
>>>>>>>> according to Nicolai:
>>>>>>>>
>>>>>>>> amdgpu_cs_ioctl *can* return -ECANCELED, but to be frankly
>>>>>>>> speaking, kernel part doesn't have any place with "-ECANCELED" so
>>>>>>>> this solution on MESA side doesn't align with *current* amdgpu
>>>>>>>> driver,
>>>>>>>> which only return 0 on success or -EINVALID on other error but
>>>>>>>> definitely no "-ECANCELED" error code,
>>>>>>>>
>>>>>>>> so if we talking about community rules we shouldn't let MESA
>>>>>>>> handle -ECANCELED , we should have a unified error code
>>>>>>>>
>>>>>>>> + Marek
>>>>>>>>
>>>>>>>> BR Monk
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: Haehnle, Nicolai
>>>>>>>> Sent: 2017å¹´10æ??9æ?¥ 18:14
>>>>>>>> To: Koenig, Christian <Christian.Koenig at amd.com>; Liu, Monk
>>>>>>>> <Monk.Liu at amd.com>; Nicolai Hähnle <nhaehnle at gmail.com>;
>>>>>>>> amd-gfx at lists.freedesktop.org
>>>>>>>> Subject: Re: [PATCH 5/5] drm/amd/sched: signal and free remaining
>>>>>>>> fences in amd_sched_entity_fini
>>>>>>>>
>>>>>>>> On 09.10.2017 10:02, Christian König wrote:
>>>>>>>>>> For gpu reset patches (already submitted to pub) I would make
>>>>>>>>>> kernel
>>>>>>>>>> return -ENODEV if the waiting fence (in cs_wait or wait_fences
>>>>>>>>>> IOCTL)
>>>>>>>>>> founded as error, that way UMD would run into robust extension
>>>>>>>>>> path
>>>>>>>>>> and considering the GPU hang occurred,
>>>>>>>>> Well that is only closed source behavior which is completely
>>>>>>>>> irrelevant for upstream development.
>>>>>>>>>
>>>>>>>>> As far as I know we haven't pushed the change to return -ENODEV
>>>>>>>>> upstream.
>>>>>>>>
>>>>>>>> FWIW, radeonsi currently expects -ECANCELED on CS submissions and
>>>>>>>> treats those as context lost. Perhaps we could use the same error
>>>>>>>> on fences?
>>>>>>>> That makes more sense to me than -ENODEV.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Nicolai
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Regards,
>>>>>>>>> Christian.
>>>>>>>>>
>>>>>>>>> Am 09.10.2017 um 08:42 schrieb Liu, Monk:
>>>>>>>>>> Christian
>>>>>>>>>>
>>>>>>>>>>> It would be really nice to have an error code set on
>>>>>>>>>>> s_fence->finished before it is signaled, use
>>>>>>>>>>> dma_fence_set_error()
>>>>>>>>>>> for this.
>>>>>>>>>> For gpu reset patches (already submitted to pub) I would make
>>>>>>>>>> kernel
>>>>>>>>>> return -ENODEV if the waiting fence (in cs_wait or wait_fences
>>>>>>>>>> IOCTL)
>>>>>>>>>> founded as error, that way UMD would run into robust extension
>>>>>>>>>> path
>>>>>>>>>> and considering the GPU hang occurred,
>>>>>>>>>>
>>>>>>>>>> Don't know if this is expected for the case of normal process
>>>>>>>>>> being
>>>>>>>>>> killed or crashed like Nicolai hit ... since there is no gpu
>>>>>>>>>> hang hit
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> BR Monk
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On
>>>>>>>>>> Behalf Of Christian K?nig
>>>>>>>>>> Sent: 2017å¹´9æ??28æ?¥ 23:01
>>>>>>>>>> To: Nicolai Hähnle <nhaehnle at gmail.com>;
>>>>>>>>>> amd-gfx at lists.freedesktop.org
>>>>>>>>>> Cc: Haehnle, Nicolai <Nicolai.Haehnle at amd.com>
>>>>>>>>>> Subject: Re: [PATCH 5/5] drm/amd/sched: signal and free remaining
>>>>>>>>>> fences in amd_sched_entity_fini
>>>>>>>>>>
>>>>>>>>>> Am 28.09.2017 um 16:55 schrieb Nicolai Hähnle:
>>>>>>>>>>> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>>>>>>>>>>>
>>>>>>>>>>> Highly concurrent Piglit runs can trigger a race condition
>>>>>>>>>>> where a
>>>>>>>>>>> pending SDMA job on a buffer object is never executed because the
>>>>>>>>>>> corresponding process is killed (perhaps due to a crash).
>>>>>>>>>>> Since the
>>>>>>>>>>> job's fences were never signaled, the buffer object was
>>>>>>>>>>> effectively
>>>>>>>>>>> leaked. Worse, the buffer was stuck wherever it happened to be at
>>>>>>>>>>> the time, possibly in VRAM.
>>>>>>>>>>>
>>>>>>>>>>> The symptom was user space processes stuck in interruptible waits
>>>>>>>>>>> with kernel stacks like:
>>>>>>>>>>>
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffbc5e6722>] dma_fence_default_wait+0x112/0x250
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffbc5e6399>] dma_fence_wait_timeout+0x39/0xf0
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffbc5e82d2>]
>>>>>>>>>>> reservation_object_wait_timeout_rcu+0x1c2/0x300
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc03ce56f>]
>>>>>>>>>>> ttm_bo_cleanup_refs_and_unlock+0xff/0x1a0
>>>>>>>>>>> [ttm]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc03cf1ea>] ttm_mem_evict_first+0xba/0x1a0 [ttm]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc03cf611>] ttm_bo_mem_space+0x341/0x4c0 [ttm]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc03cfc54>] ttm_bo_validate+0xd4/0x150 [ttm]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc03cffbd>] ttm_bo_init_reserved+0x2ed/0x420
>>>>>>>>>>> [ttm]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc042f523>]
>>>>>>>>>>> amdgpu_bo_create_restricted+0x1f3/0x470
>>>>>>>>>>> [amdgpu]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc042f9fa>] amdgpu_bo_create+0xda/0x220 [amdgpu]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc04349ea>] amdgpu_gem_object_create+0xaa/0x140
>>>>>>>>>>> [amdgpu]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc0434f97>] amdgpu_gem_create_ioctl+0x97/0x120
>>>>>>>>>>> [amdgpu]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc037ddba>] drm_ioctl+0x1fa/0x480 [drm]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffc041904f>] amdgpu_drm_ioctl+0x4f/0x90 [amdgpu]
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffbc23db33>] do_vfs_ioctl+0xa3/0x5f0
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffbc23e0f9>] SyS_ioctl+0x79/0x90
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffbc864ffb>] entry_SYSCALL_64_fastpath+0x1e/0xad
>>>>>>>>>>> Â Â Â Â Â Â [<ffffffffffffffff>] 0xffffffffffffffff
>>>>>>>>>>>
>>>>>>>>>>> Signed-off-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
>>>>>>>>>>> Acked-by: Christian König <christian.koenig at amd.com>
>>>>>>>>>>> ---
>>>>>>>>>>> Â Â Â drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 7 ++++++-
>>>>>>>>>>> Â Â Â 1 file changed, 6 insertions(+), 1 deletion(-)
>>>>>>>>>>>
>>>>>>>>>>> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>>>>>>>> b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>>>>>>>> index 54eb77cffd9b..32a99e980d78 100644
>>>>>>>>>>> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>>>>>>>> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>>>>>>>>>> @@ -220,22 +220,27 @@ void amd_sched_entity_fini(struct
>>>>>>>>>>> amd_gpu_scheduler *sched,
>>>>>>>>>>> amd_sched_entity_is_idle(entity));
>>>>>>>>>>> Â Â Â Â Â Â Â amd_sched_rq_remove_entity(rq, entity);
>>>>>>>>>>> Â Â Â Â Â Â Â if (r) {
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â struct amd_sched_job *job;
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â /* Park the kernel for a moment to make sure it isn't
>>>>>>>>>>> processing
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â Â * our enity.
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â Â */
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â kthread_park(sched->thread);
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â kthread_unpark(sched->thread);
>>>>>>>>>>> -Â Â Â Â Â Â Â while (kfifo_out(&entity->job_queue, &job, sizeof(job)))
>>>>>>>>>>> +Â Â Â Â Â Â Â while (kfifo_out(&entity->job_queue, &job,
>>>>>>>>>>> sizeof(job))) {
>>>>>>>>>>> +Â Â Â Â Â Â Â Â Â Â Â struct amd_sched_fence *s_fence = job->s_fence;
>>>>>>>>>>> +Â Â Â Â Â Â Â Â Â Â Â amd_sched_fence_scheduled(s_fence);
>>>>>>>>>> It would be really nice to have an error code set on
>>>>>>>>>> s_fence->finished before it is signaled, use
>>>>>>>>>> dma_fence_set_error() for this.
>>>>>>>>>>
>>>>>>>>>> Additional to that it would be nice to note in the subject line
>>>>>>>>>> that
>>>>>>>>>> this is a rather important bug fix.
>>>>>>>>>>
>>>>>>>>>> With that fixed the whole series is Reviewed-by: Christian König
>>>>>>>>>> <christian.koenig at amd.com>.
>>>>>>>>>>
>>>>>>>>>> Regards,
>>>>>>>>>> Christian.
>>>>>>>>>>
>>>>>>>>>>> + amd_sched_fence_finished(s_fence);
>>>>>>>>>>> + dma_fence_put(&s_fence->finished);
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â sched->ops->free_job(job);
>>>>>>>>>>> +Â Â Â Â Â Â Â }
>>>>>>>>>>> Â Â Â Â Â Â Â }
>>>>>>>>>>> Â Â Â Â Â Â Â kfifo_free(&entity->job_queue);
>>>>>>>>>>> Â Â Â }
>>>>>>>>>>> Â Â Â static void amd_sched_entity_wakeup(struct dma_fence *f,
>>>>>>>>>>> struct
>>>>>>>>>>> dma_fence_cb *cb)
>>>>>>>>>>> Â Â Â {
>>>>>>>>>>> Â Â Â Â Â Â Â struct amd_sched_entity *entity =
>>>>>>>>>>> Â Â Â Â Â Â Â Â Â Â Â container_of(cb, struct amd_sched_entity, cb);
>>>>>>>>>>> Â Â Â Â Â Â Â entity->dependency = NULL;
>>>>>>>>>>
>>>>>>>>>> _______________________________________________
>>>>>>>>>> amd-gfx mailing list
>>>>>>>>>> amd-gfx at lists.freedesktop.org
>>>>>>>>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>>>>>>>>>> _______________________________________________
>>>>>>>>>> amd-gfx mailing list
>>>>>>>>>> amd-gfx at lists.freedesktop.org
>>>>>>>>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
