[PATCH v2] drm/amdkfd: don't use dqm lock during device reset/suspend/resume
Yang, Philip
Philip.Yang at amd.com
Tue Oct 22 19:52:27 UTC 2019
On 2019-10-22 2:44 p.m., Kuehling, Felix wrote:
> On 2019-10-22 14:28, 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.
>>
>> 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>
>
> Three more comments inline. With those comments addressed, this patch is
>
> Reviewed-by: Felix Kuehling <Felix.Kuehling 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;
>> -
>
> Is this part of the change still needed? I remember that this sequence
> was a bit tricky with some potential race condition when Shaoyun was
> working on it. This may have unintended side effects.
>
>
Revert this change to be safe, it is not needed and not clear if there
are side effects.
>> 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;
>
> Add a WARN here as well. When the scheduler is not running the queues
> should already be evicted.
>
Done
>
>> +
>> 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;
>
> Add a WARN here as well. This should not happen while we're suspended.
>
Done.
> Regards,
> Felix
>
>> +
>> 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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