[PATCH v2] drm/amdkfd: don't use dqm lock during device reset/suspend/resume
Grodzovsky, Andrey
Andrey.Grodzovsky at amd.com
Tue Oct 22 20:19:13 UTC 2019
On 10/22/19 4:04 PM, Yang, Philip wrote:
>
> On 2019-10-22 3:36 p.m., Grodzovsky, Andrey wrote:
>> On 10/22/19 3:19 PM, Yang, Philip wrote:
>>> On 2019-10-22 2:40 p.m., Grodzovsky, Andrey wrote:
>>>> On 10/22/19 2:38 PM, Grodzovsky, Andrey wrote:
>>>>> On 10/22/19 2:28 PM, Yang, Philip wrote:
>>>>>> If device reset/suspend/resume failed for some reason, dqm lock is
>>>>>> hold forever and this causes deadlock. Below is a kernel backtrace when
>>>>>> application open kfd after suspend/resume failed.
>>>>>>
>>>>>> Instead of holding dqm lock in pre_reset and releasing dqm lock in
>>>>>> post_reset, add dqm->device_stopped flag which is modified in
>>>>>> dqm->ops.start and dqm->ops.stop. The flag doesn't need lock protection
>>>>>> because write/read are all inside dqm lock.
>>>>>>
>>>>>> For HWS case, map_queues_cpsch and unmap_queues_cpsch checks
>>>>>> device_stopped flag before sending the updated runlist.
>>>>> Is there a chance of race condition here where dqm->device_stopped
>>>>> returns true for some operation (e.g.map_queues_cpsch) but just as it
>>>>> proceeds GPU reset starts ?
>>>>>
>>>>> Andrey
>>>> Correction -
>>>>
>>>> dqm->device_stopped returns FALSE
>>>>
>>> No race condition here, dqm->device_stopped is set to FALSE in
>>> kgd2kfd_post_reset -> dqm->ops.start(), which the last step of
>>> amdgpu_device_gpu_recover, so it's safe to do map_queue_cpsch.
>>>
>>> Regards,
>>> Philip
>> Sorry - i was confused by the commit description vs. body - in the
>> description it's called device_stopped flag while in the body it's
>> sched_running - probably the description needs to be fixed.
>>
> Thanks, commit description is updated.
>
>> So i mean the switch true->false when GPU reset just begins - you get an
>> IOCTL to map a queue (if i understood KFD code correctly), check
>> dqm->sched_running == true and continue, what if right then GPU reset
>> started due to some issue like job timeout or user triggered reset -
>> dqm->sched_running becomes false but you already past that checkpoint in
>> the IOCTL, no ?
>>
> map a queue is done under dqm lock, to send the updated runlist to HWS,
> then relase dqm lock. GPU reset start pre_reset will unmap all queues
> first under dqm lock, then set dqm->sched_running to false, release dqm
> lock, and then continue to reset HW. dqm lock guarantee the two
> operations are serialized.
>
> Philip
I see now that it's ok.
Andrey
>
>> Andrey
>>
>>>> Andrey
>>>>
>>>>>> v2: For no-HWS case, when device is stopped, don't call
>>>>>> load/destroy_mqd for eviction, restore and create queue, and avoid
>>>>>> debugfs dump hdqs.
>>>>>>
>>>>>> Backtrace of dqm lock deadlock:
>>>>>>
>>>>>> [Thu Oct 17 16:43:37 2019] INFO: task rocminfo:3024 blocked for more
>>>>>> than 120 seconds.
>>>>>> [Thu Oct 17 16:43:37 2019] Not tainted
>>>>>> 5.0.0-rc1-kfd-compute-rocm-dkms-no-npi-1131 #1
>>>>>> [Thu Oct 17 16:43:37 2019] "echo 0 >
>>>>>> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>>>> [Thu Oct 17 16:43:37 2019] rocminfo D 0 3024 2947
>>>>>> 0x80000000
>>>>>> [Thu Oct 17 16:43:37 2019] Call Trace:
>>>>>> [Thu Oct 17 16:43:37 2019] ? __schedule+0x3d9/0x8a0
>>>>>> [Thu Oct 17 16:43:37 2019] schedule+0x32/0x70
>>>>>> [Thu Oct 17 16:43:37 2019] schedule_preempt_disabled+0xa/0x10
>>>>>> [Thu Oct 17 16:43:37 2019] __mutex_lock.isra.9+0x1e3/0x4e0
>>>>>> [Thu Oct 17 16:43:37 2019] ? __call_srcu+0x264/0x3b0
>>>>>> [Thu Oct 17 16:43:37 2019] ? process_termination_cpsch+0x24/0x2f0
>>>>>> [amdgpu]
>>>>>> [Thu Oct 17 16:43:37 2019] process_termination_cpsch+0x24/0x2f0
>>>>>> [amdgpu]
>>>>>> [Thu Oct 17 16:43:37 2019]
>>>>>> kfd_process_dequeue_from_all_devices+0x42/0x60 [amdgpu]
>>>>>> [Thu Oct 17 16:43:37 2019] kfd_process_notifier_release+0x1be/0x220
>>>>>> [amdgpu]
>>>>>> [Thu Oct 17 16:43:37 2019] __mmu_notifier_release+0x3e/0xc0
>>>>>> [Thu Oct 17 16:43:37 2019] exit_mmap+0x160/0x1a0
>>>>>> [Thu Oct 17 16:43:37 2019] ? __handle_mm_fault+0xba3/0x1200
>>>>>> [Thu Oct 17 16:43:37 2019] ? exit_robust_list+0x5a/0x110
>>>>>> [Thu Oct 17 16:43:37 2019] mmput+0x4a/0x120
>>>>>> [Thu Oct 17 16:43:37 2019] do_exit+0x284/0xb20
>>>>>> [Thu Oct 17 16:43:37 2019] ? handle_mm_fault+0xfa/0x200
>>>>>> [Thu Oct 17 16:43:37 2019] do_group_exit+0x3a/0xa0
>>>>>> [Thu Oct 17 16:43:37 2019] __x64_sys_exit_group+0x14/0x20
>>>>>> [Thu Oct 17 16:43:37 2019] do_syscall_64+0x4f/0x100
>>>>>> [Thu Oct 17 16:43:37 2019] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>>>>>
>>>>>> Suggested-by: Felix Kuehling <Felix.Kuehling at amd.com>
>>>>>> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>>>>>> ---
>>>>>> drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 6 +--
>>>>>> drivers/gpu/drm/amd/amdkfd/kfd_device.c | 5 --
>>>>>> .../drm/amd/amdkfd/kfd_device_queue_manager.c | 47 +++++++++++++++++--
>>>>>> .../drm/amd/amdkfd/kfd_device_queue_manager.h | 1 +
>>>>>> 4 files changed, 46 insertions(+), 13 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>>>>> index d9e36dbf13d5..40d75c39f08e 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>>>>> @@ -120,13 +120,13 @@ static int kfd_open(struct inode *inode, struct file *filep)
>>>>>> return -EPERM;
>>>>>> }
>>>>>>
>>>>>> + if (kfd_is_locked())
>>>>>> + return -EAGAIN;
>>>>>> +
>>>>>> process = kfd_create_process(filep);
>>>>>> if (IS_ERR(process))
>>>>>> return PTR_ERR(process);
>>>>>>
>>>>>> - if (kfd_is_locked())
>>>>>> - return -EAGAIN;
>>>>>> -
>>>>>> dev_dbg(kfd_device, "process %d opened, compat mode (32 bit) - %d\n",
>>>>>> process->pasid, process->is_32bit_user_mode);
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
>>>>>> index 8f4b24e84964..4fa8834ce7cb 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
>>>>>> @@ -730,9 +730,6 @@ int kgd2kfd_pre_reset(struct kfd_dev *kfd)
>>>>>> return 0;
>>>>>> kgd2kfd_suspend(kfd);
>>>>>>
>>>>>> - /* hold dqm->lock to prevent further execution*/
>>>>>> - dqm_lock(kfd->dqm);
>>>>>> -
>>>>>> kfd_signal_reset_event(kfd);
>>>>>> return 0;
>>>>>> }
>>>>>> @@ -750,8 +747,6 @@ int kgd2kfd_post_reset(struct kfd_dev *kfd)
>>>>>> if (!kfd->init_complete)
>>>>>> return 0;
>>>>>>
>>>>>> - dqm_unlock(kfd->dqm);
>>>>>> -
>>>>>> ret = kfd_resume(kfd);
>>>>>> if (ret)
>>>>>> return ret;
>>>>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
>>>>>> index 81fb545cf42c..82e1c6280d13 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
>>>>>> @@ -340,6 +340,10 @@ static int create_queue_nocpsch(struct device_queue_manager *dqm,
>>>>>> mqd_mgr->init_mqd(mqd_mgr, &q->mqd, q->mqd_mem_obj,
>>>>>> &q->gart_mqd_addr, &q->properties);
>>>>>> if (q->properties.is_active) {
>>>>>> + if (!dqm->sched_running) {
>>>>>> + WARN_ONCE(1, "Load non-HWS mqd while stopped\n");
>>>>>> + goto add_queue_to_list;
>>>>>> + }
>>>>>>
>>>>>> if (WARN(q->process->mm != current->mm,
>>>>>> "should only run in user thread"))
>>>>>> @@ -351,6 +355,7 @@ static int create_queue_nocpsch(struct device_queue_manager *dqm,
>>>>>> goto out_free_mqd;
>>>>>> }
>>>>>>
>>>>>> +add_queue_to_list:
>>>>>> list_add(&q->list, &qpd->queues_list);
>>>>>> qpd->queue_count++;
>>>>>> if (q->properties.is_active)
>>>>>> @@ -458,6 +463,11 @@ static int destroy_queue_nocpsch_locked(struct device_queue_manager *dqm,
>>>>>>
>>>>>> deallocate_doorbell(qpd, q);
>>>>>>
>>>>>> + if (!dqm->sched_running) {
>>>>>> + WARN_ONCE(1, "Destroy non-HWS queue while stopped\n");
>>>>>> + return 0;
>>>>>> + }
>>>>>> +
>>>>>> retval = mqd_mgr->destroy_mqd(mqd_mgr, q->mqd,
>>>>>> KFD_PREEMPT_TYPE_WAVEFRONT_RESET,
>>>>>> KFD_UNMAP_LATENCY_MS,
>>>>>> @@ -533,6 +543,12 @@ static int update_queue(struct device_queue_manager *dqm, struct queue *q)
>>>>>> (q->properties.type == KFD_QUEUE_TYPE_COMPUTE ||
>>>>>> q->properties.type == KFD_QUEUE_TYPE_SDMA ||
>>>>>> q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) {
>>>>>> +
>>>>>> + if (!dqm->sched_running) {
>>>>>> + WARN_ONCE(1, "Update non-HWS queue while stopped\n");
>>>>>> + goto out_unlock;
>>>>>> + }
>>>>>> +
>>>>>> retval = mqd_mgr->destroy_mqd(mqd_mgr, q->mqd,
>>>>>> KFD_PREEMPT_TYPE_WAVEFRONT_DRAIN,
>>>>>> KFD_UNMAP_LATENCY_MS, q->pipe, q->queue);
>>>>>> @@ -602,6 +618,11 @@ static int evict_process_queues_nocpsch(struct device_queue_manager *dqm,
>>>>>> mqd_mgr = dqm->mqd_mgrs[get_mqd_type_from_queue_type(
>>>>>> q->properties.type)];
>>>>>> q->properties.is_active = false;
>>>>>> + dqm->queue_count--;
>>>>>> +
>>>>>> + if (!dqm->sched_running)
>>>>>> + continue;
>>>>>> +
>>>>>> retval = mqd_mgr->destroy_mqd(mqd_mgr, q->mqd,
>>>>>> KFD_PREEMPT_TYPE_WAVEFRONT_DRAIN,
>>>>>> KFD_UNMAP_LATENCY_MS, q->pipe, q->queue);
>>>>>> @@ -610,7 +631,6 @@ static int evict_process_queues_nocpsch(struct device_queue_manager *dqm,
>>>>>> * maintain a consistent eviction state
>>>>>> */
>>>>>> ret = retval;
>>>>>> - dqm->queue_count--;
>>>>>> }
>>>>>>
>>>>>> out:
>>>>>> @@ -711,6 +731,11 @@ static int restore_process_queues_nocpsch(struct device_queue_manager *dqm,
>>>>>> mqd_mgr = dqm->mqd_mgrs[get_mqd_type_from_queue_type(
>>>>>> q->properties.type)];
>>>>>> q->properties.is_active = true;
>>>>>> + dqm->queue_count++;
>>>>>> +
>>>>>> + if (!dqm->sched_running)
>>>>>> + continue;
>>>>>> +
>>>>>> retval = mqd_mgr->load_mqd(mqd_mgr, q->mqd, q->pipe,
>>>>>> q->queue, &q->properties, mm);
>>>>>> if (retval && !ret)
>>>>>> @@ -718,7 +743,6 @@ static int restore_process_queues_nocpsch(struct device_queue_manager *dqm,
>>>>>> * maintain a consistent eviction state
>>>>>> */
>>>>>> ret = retval;
>>>>>> - dqm->queue_count++;
>>>>>> }
>>>>>> qpd->evicted = 0;
>>>>>> out:
>>>>>> @@ -915,7 +939,8 @@ static int start_nocpsch(struct device_queue_manager *dqm)
>>>>>>
>>>>>> if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
>>>>>> return pm_init(&dqm->packets, dqm);
>>>>>> -
>>>>>> + dqm->sched_running = true;
>>>>>> +
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> @@ -923,7 +948,8 @@ static int stop_nocpsch(struct device_queue_manager *dqm)
>>>>>> {
>>>>>> if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
>>>>>> pm_uninit(&dqm->packets);
>>>>>> -
>>>>>> + dqm->sched_running = false;
>>>>>> +
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> @@ -1074,6 +1100,7 @@ static int start_cpsch(struct device_queue_manager *dqm)
>>>>>> dqm_lock(dqm);
>>>>>> /* clear hang status when driver try to start the hw scheduler */
>>>>>> dqm->is_hws_hang = false;
>>>>>> + dqm->sched_running = true;
>>>>>> execute_queues_cpsch(dqm, KFD_UNMAP_QUEUES_FILTER_DYNAMIC_QUEUES, 0);
>>>>>> dqm_unlock(dqm);
>>>>>>
>>>>>> @@ -1089,6 +1116,7 @@ static int stop_cpsch(struct device_queue_manager *dqm)
>>>>>> {
>>>>>> dqm_lock(dqm);
>>>>>> unmap_queues_cpsch(dqm, KFD_UNMAP_QUEUES_FILTER_ALL_QUEUES, 0);
>>>>>> + dqm->sched_running = false;
>>>>>> dqm_unlock(dqm);
>>>>>>
>>>>>> kfd_gtt_sa_free(dqm->dev, dqm->fence_mem);
>>>>>> @@ -1275,9 +1303,10 @@ static int map_queues_cpsch(struct device_queue_manager *dqm)
>>>>>> {
>>>>>> int retval;
>>>>>>
>>>>>> + if (!dqm->sched_running)
>>>>>> + return 0;
>>>>>> if (dqm->queue_count <= 0 || dqm->processes_count <= 0)
>>>>>> return 0;
>>>>>> -
>>>>>> if (dqm->active_runlist)
>>>>>> return 0;
>>>>>>
>>>>>> @@ -1299,6 +1328,8 @@ static int unmap_queues_cpsch(struct device_queue_manager *dqm,
>>>>>> {
>>>>>> int retval = 0;
>>>>>>
>>>>>> + if (!dqm->sched_running)
>>>>>> + return 0;
>>>>>> if (dqm->is_hws_hang)
>>>>>> return -EIO;
>>>>>> if (!dqm->active_runlist)
>>>>>> @@ -1903,6 +1934,12 @@ int dqm_debugfs_hqds(struct seq_file *m, void *data)
>>>>>> int pipe, queue;
>>>>>> int r = 0;
>>>>>>
>>>>>> + if (!dqm->sched_running) {
>>>>>> + seq_printf(m, " Device is stopped\n");
>>>>>> +
>>>>>> + return 0;
>>>>>> + }
>>>>>> +
>>>>>> r = dqm->dev->kfd2kgd->hqd_dump(dqm->dev->kgd,
>>>>>> KFD_CIK_HIQ_PIPE, KFD_CIK_HIQ_QUEUE,
>>>>>> &dump, &n_regs);
>>>>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
>>>>>> index 2eaea6b04cbe..a8c37e6da027 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
>>>>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
>>>>>> @@ -201,6 +201,7 @@ struct device_queue_manager {
>>>>>> bool is_hws_hang;
>>>>>> struct work_struct hw_exception_work;
>>>>>> struct kfd_mem_obj hiq_sdma_mqd;
>>>>>> + bool sched_running;
>>>>>> };
>>>>>>
>>>>>> void device_queue_manager_init_cik(
>>>>> _______________________________________________
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