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@xxxxxxx>
> Signed-off-by: Philip Yang <Philip.Yang@xxxxxxx>
Three more comments inline. With those comments addressed, this patch is
Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
> ---
> 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.
> 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.
> +
> 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.
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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