[PATCH v2] drm/amdkfd: don't use dqm lock during device reset/suspend/resume
Yang, Philip
Philip.Yang at amd.com
Tue Oct 22 20:04:39 UTC 2019
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
> 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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