[PATCH 1/2] drm/amdgpu:resolv deadlock between reset and cs_ioctl v4.

andrey andrey.grodzovsky at amd.com
Tue Oct 10 03:31:26 UTC 2017



On 2017-10-09 04:34 AM, Christian K├Ânig wrote:
> Am 06.10.2017 um 20:20 schrieb Andrey Grodzovsky:
>> From: Monk Liu <Monk.Liu at amd.com>
>>
>> need to unreserve ttm bo before "cs_add_fence" and "entity_push_job"
>> otherwise there will be deadlock between "recover_vram_from_shadow"
>> and previous two routines on the ttm bo's resv lock.
>>
>> v2:
>> Add per ctx mutex.
>>
>> v3:
>> Rellocate mutex aquisition into amdgpu_cs_parser_init and muex release
>> into amdgpu_cs_parser_fini to avoid nested locking lockup.
>> Add rollback code for amdgpu_ctx_add_fence in case of error or signal
>> interruption.
>>
>> v4:
>> Refactor amdgpu_cs_ib_vm_chunk and amdgpu_cs_ib_fill to enable
>> old fence waiting before reservation lock is aquired.
>>
>> Change-Id: Ia209beab5036bfc2c38cbf18324fa3efd4bab1cf
>> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h     |   1 +
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c  | 164 
>> ++++++++++++++++++--------------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c |   4 +
>>   3 files changed, 100 insertions(+), 69 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> index 53d8df3..baa2953 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> @@ -724,6 +724,7 @@ struct amdgpu_ctx {
>>       struct dma_fence    **fences;
>>       struct amdgpu_ctx_ring    rings[AMDGPU_MAX_RINGS];
>>       bool preamble_presented;
>> +    struct mutex        lock;
>>   };
>>     struct amdgpu_ctx_mgr {
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 9f1202a..0fa1bc7 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -89,6 +89,9 @@ static int amdgpu_cs_parser_init(struct 
>> amdgpu_cs_parser *p, void *data)
>>           goto free_chunk;
>>       }
>>   +
>> +    mutex_lock(&p->ctx->lock);
>> +
>>       /* get chunks */
>>       chunk_array_user = u64_to_user_ptr(cs->in.chunks);
>>       if (copy_from_user(chunk_array, chunk_array_user,
>> @@ -715,28 +718,21 @@ static int amdgpu_cs_sync_rings(struct 
>> amdgpu_cs_parser *p)
>>   /**
>>    * cs_parser_fini() - clean parser states
>>    * @parser:    parser structure holding parsing context.
>> - * @error:    error number
>> - *
>> - * If error is set than unvalidate buffer, otherwise just free memory
>> - * used by parsing context.
>>    **/
>> -static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser, 
>> int error,
>> -                  bool backoff)
>> +static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser *parser)
>
> You can now drop this change and keep the logic as it is since we 
> moved the wait before taking the reservation locks.

By "this change" here and in the comment later bellow I guess you mean 
the original change by Monk about moving ttm_eu_fence_buffer_objects to 
before amd_sched_entity_push_job ? In that case I am not sure how we can 
drop it since the wait we moved in the second patch was the one for the 
old fence while Monk's change was about the wait happening when the 
kfifo is full. Isn't reverting his change will just put us again in the 
original deadlock of blocking on full kfifo while holding the 
reservation lock during gpu reset with VRAM recovery ?

Thanks,
Andrey

>
>>   {
>>       unsigned i;
>>   -    if (error && backoff)
>> -        ttm_eu_backoff_reservation(&parser->ticket,
>> -                       &parser->validated);
>> -
>>       for (i = 0; i < parser->num_post_dep_syncobjs; i++)
>>           drm_syncobj_put(parser->post_dep_syncobjs[i]);
>>       kfree(parser->post_dep_syncobjs);
>>         dma_fence_put(parser->fence);
>>   -    if (parser->ctx)
>> +    if (parser->ctx) {
>> +        mutex_unlock(&parser->ctx->lock);
>>           amdgpu_ctx_put(parser->ctx);
>> +    }
>>       if (parser->bo_list)
>>           amdgpu_bo_list_put(parser->bo_list);
>>   @@ -843,7 +839,72 @@ static int amdgpu_cs_ib_vm_chunk(struct 
>> amdgpu_device *adev,
>>       struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
>>       struct amdgpu_vm *vm = &fpriv->vm;
>>       struct amdgpu_ring *ring = p->job->ring;
>> -    int i, r;
>> +    int i, j, r;
>> +
>> +    for (i = 0, j = 0; i < p->nchunks && j < p->job->num_ibs; i++) {
>> +
>> +        struct amdgpu_cs_chunk *chunk;
>> +        struct amdgpu_ib *ib;
>> +        struct drm_amdgpu_cs_chunk_ib *chunk_ib;
>> +
>> +        chunk = &p->chunks[i];
>> +        ib = &p->job->ibs[j];
>> +        chunk_ib = (struct drm_amdgpu_cs_chunk_ib *)chunk->kdata;
>> +
>> +        if (chunk->chunk_id != AMDGPU_CHUNK_ID_IB)
>> +                    continue;
>> +
>> +        if (p->job->ring->funcs->parse_cs) {
>> +            struct amdgpu_bo_va_mapping *m;
>> +            struct amdgpu_bo *aobj = NULL;
>> +            uint64_t offset;
>> +            uint8_t *kptr;
>> +
>> +            r = amdgpu_cs_find_mapping(p, chunk_ib->va_start,
>> +                           &aobj, &m);
>> +            if (r) {
>> +                DRM_ERROR("IB va_start is invalid\n");
>> +                return r;
>> +            }
>> +
>> +            if ((chunk_ib->va_start + chunk_ib->ib_bytes) >
>> +                (m->last + 1) * AMDGPU_GPU_PAGE_SIZE) {
>> +                DRM_ERROR("IB va_start+ib_bytes is invalid\n");
>> +                return -EINVAL;
>> +            }
>> +
>> +            /* the IB should be reserved at this point */
>> +            r = amdgpu_bo_kmap(aobj, (void **)&kptr);
>> +            if (r) {
>> +                return r;
>> +            }
>> +
>> +            offset = m->start * AMDGPU_GPU_PAGE_SIZE;
>> +            kptr += chunk_ib->va_start - offset;
>> +
>> +            r =  amdgpu_ib_get(adev, vm, chunk_ib->ib_bytes, ib);
>> +            if (r) {
>> +                DRM_ERROR("Failed to get ib !\n");
>> +                return r;
>> +            }
>> +
>> +            memcpy(ib->ptr, kptr, chunk_ib->ib_bytes);
>> +            amdgpu_bo_kunmap(aobj);
>> +        } else {
>> +            r =  amdgpu_ib_get(adev, vm, 0, ib);
>> +            if (r) {
>> +                DRM_ERROR("Failed to get ib !\n");
>> +                return r;
>> +            }
>> +
>> +        }
>> +
>> +        ib->gpu_addr = chunk_ib->va_start;
>> +        ib->length_dw = chunk_ib->ib_bytes / 4;
>> +        ib->flags = chunk_ib->flags;
>
> Please keep the calls to amdgpu_ib_get() inside amdgpu_cs_ib_fill().
>
>> +        j++;
>> +
>> +    }
>>         /* Only for UVD/VCE VM emulation */
>>       if (ring->funcs->parse_cs) {
>> @@ -868,19 +929,15 @@ static int amdgpu_cs_ib_vm_chunk(struct 
>> amdgpu_device *adev,
>>   static int amdgpu_cs_ib_fill(struct amdgpu_device *adev,
>>                    struct amdgpu_cs_parser *parser)
>>   {
>> -    struct amdgpu_fpriv *fpriv = parser->filp->driver_priv;
>> -    struct amdgpu_vm *vm = &fpriv->vm;
>>       int i, j;
>>       int r, ce_preempt = 0, de_preempt = 0;
>>         for (i = 0, j = 0; i < parser->nchunks && j < 
>> parser->job->num_ibs; i++) {
>>           struct amdgpu_cs_chunk *chunk;
>> -        struct amdgpu_ib *ib;
>>           struct drm_amdgpu_cs_chunk_ib *chunk_ib;
>>           struct amdgpu_ring *ring;
>>             chunk = &parser->chunks[i];
>> -        ib = &parser->job->ibs[j];
>>           chunk_ib = (struct drm_amdgpu_cs_chunk_ib *)chunk->kdata;
>>             if (chunk->chunk_id != AMDGPU_CHUNK_ID_IB)
>> @@ -917,54 +974,6 @@ static int amdgpu_cs_ib_fill(struct 
>> amdgpu_device *adev,
>>             parser->job->ring = ring;
>>   -        if (ring->funcs->parse_cs) {
>> -            struct amdgpu_bo_va_mapping *m;
>> -            struct amdgpu_bo *aobj = NULL;
>> -            uint64_t offset;
>> -            uint8_t *kptr;
>> -
>> -            r = amdgpu_cs_find_mapping(parser, chunk_ib->va_start,
>> -                           &aobj, &m);
>> -            if (r) {
>> -                DRM_ERROR("IB va_start is invalid\n");
>> -                return r;
>> -            }
>> -
>> -            if ((chunk_ib->va_start + chunk_ib->ib_bytes) >
>> -                (m->last + 1) * AMDGPU_GPU_PAGE_SIZE) {
>> -                DRM_ERROR("IB va_start+ib_bytes is invalid\n");
>> -                return -EINVAL;
>> -            }
>> -
>> -            /* the IB should be reserved at this point */
>> -            r = amdgpu_bo_kmap(aobj, (void **)&kptr);
>> -            if (r) {
>> -                return r;
>> -            }
>> -
>> -            offset = m->start * AMDGPU_GPU_PAGE_SIZE;
>> -            kptr += chunk_ib->va_start - offset;
>> -
>> -            r =  amdgpu_ib_get(adev, vm, chunk_ib->ib_bytes, ib);
>> -            if (r) {
>> -                DRM_ERROR("Failed to get ib !\n");
>> -                return r;
>> -            }
>> -
>> -            memcpy(ib->ptr, kptr, chunk_ib->ib_bytes);
>> -            amdgpu_bo_kunmap(aobj);
>> -        } else {
>> -            r =  amdgpu_ib_get(adev, vm, 0, ib);
>> -            if (r) {
>> -                DRM_ERROR("Failed to get ib !\n");
>> -                return r;
>> -            }
>> -
>> -        }
>> -
>> -        ib->gpu_addr = chunk_ib->va_start;
>> -        ib->length_dw = chunk_ib->ib_bytes / 4;
>> -        ib->flags = chunk_ib->flags;
>>           j++;
>>       }
>>   @@ -1160,14 +1169,26 @@ static int amdgpu_cs_submit(struct 
>> amdgpu_cs_parser *p,
>>         amdgpu_cs_post_dependencies(p);
>>   +
>> +    /* hook sched fence to all BOs' reservation in validated list
>> +     * and unreserve them.
>> +     *
>> +     * we unreserve at here is because otherwise
>> +     * there'll be deadlock between ctx_add_fence/sched_entity_push_job
>> +     * and gpu_reset routine's recover_bo_from_shadow on PD/PTEs' 
>> ttm bo lock
>> +     */
>> +    ttm_eu_fence_buffer_objects(&p->ticket, &p->validated, p->fence);
>> +
>> +
>>       cs->out.handle = amdgpu_ctx_add_fence(p->ctx, ring, p->fence);
>> +
>> +
>
> Please drop that change. It isn't necessary any more after you moved 
> the waiting outside of the BO lock.
>
> Dito for most of the other changes as well.
>
> Regards,
> Christian.
>
>>       job->uf_sequence = cs->out.handle;
>>       amdgpu_job_free_resources(job);
>>         trace_amdgpu_cs_ioctl(job);
>>       amd_sched_entity_push_job(&job->base);
>>   -    ttm_eu_fence_buffer_objects(&p->ticket, &p->validated, p->fence);
>>       amdgpu_mn_unlock(p->mn);
>>         return 0;
>> @@ -1189,6 +1210,7 @@ int amdgpu_cs_ioctl(struct drm_device *dev, 
>> void *data, struct drm_file *filp)
>>         parser.adev = adev;
>>       parser.filp = filp;
>> +    fpriv = filp->driver_priv;
>>         r = amdgpu_cs_parser_init(&parser, data);
>>       if (r) {
>> @@ -1196,6 +1218,10 @@ int amdgpu_cs_ioctl(struct drm_device *dev, 
>> void *data, struct drm_file *filp)
>>           goto out;
>>       }
>>   +    r = amdgpu_cs_ib_fill(adev, &parser);
>> +    if (r)
>> +        goto out;
>> +
>>       r = amdgpu_cs_parser_bos(&parser, data);
>>       if (r) {
>>           if (r == -ENOMEM)
>> @@ -1206,9 +1232,6 @@ int amdgpu_cs_ioctl(struct drm_device *dev, 
>> void *data, struct drm_file *filp)
>>       }
>>         reserved_buffers = true;
>> -    r = amdgpu_cs_ib_fill(adev, &parser);
>> -    if (r)
>> -        goto out;
>>         r = amdgpu_cs_dependencies(adev, &parser);
>>       if (r) {
>> @@ -1226,7 +1249,10 @@ int amdgpu_cs_ioctl(struct drm_device *dev, 
>> void *data, struct drm_file *filp)
>>       r = amdgpu_cs_submit(&parser, cs);
>>     out:
>> -    amdgpu_cs_parser_fini(&parser, r, reserved_buffers);
>> +    if (r && reserved_buffers)
>> +        ttm_eu_backoff_reservation(&parser.ticket, &parser.validated);
>> +
>> +    amdgpu_cs_parser_fini(&parser);
>>       return r;
>>   }
>>   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> index a11e443..c073a68 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> @@ -39,6 +39,8 @@ static int amdgpu_ctx_init(struct amdgpu_device 
>> *adev, struct amdgpu_ctx *ctx)
>>       if (!ctx->fences)
>>           return -ENOMEM;
>>   +    mutex_init(&ctx->lock);
>> +
>>       for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
>>           ctx->rings[i].sequence = 1;
>>           ctx->rings[i].fences = &ctx->fences[amdgpu_sched_jobs * i];
>> @@ -96,6 +98,8 @@ static void amdgpu_ctx_fini(struct amdgpu_ctx *ctx)
>>                         &ctx->rings[i].entity);
>>         amdgpu_queue_mgr_fini(adev, &ctx->queue_mgr);
>> +
>> +    mutex_destroy(&ctx->lock);
>>   }
>>     static int amdgpu_ctx_alloc(struct amdgpu_device *adev,
>
>



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