[PATCH 1/1] drm/amdkfd: Process notifier release callback don't take mutex
Felix Kuehling
felix.kuehling at amd.com
Mon Jul 11 18:54:00 UTC 2022
On 2022-07-07 17:23, Philip Yang wrote:
> Move process queues cleanup to deferred work kfd_process_wq_release, to
> avoid potential deadlock circular locking warning:
>
> WARNING: possible circular locking dependency detected
> the existing dependency chain (in reverse order) is:
> -> #2
> ((work_completion)(&svms->deferred_list_work)){+.+.}-{0:0}:
> __flush_work+0x343/0x4a0
> svm_range_list_lock_and_flush_work+0x39/0xc0
> svm_range_set_attr+0xe8/0x1080 [amdgpu]
> kfd_ioctl+0x19b/0x600 [amdgpu]
> __x64_sys_ioctl+0x81/0xb0
> do_syscall_64+0x34/0x80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> -> #1 (&info->lock#2){+.+.}-{3:3}:
> __mutex_lock+0xa4/0x940
> amdgpu_amdkfd_gpuvm_acquire_process_vm+0x2e3/0x590
> kfd_process_device_init_vm+0x61/0x200 [amdgpu]
> kfd_ioctl_acquire_vm+0x83/0xb0 [amdgpu]
> kfd_ioctl+0x19b/0x600 [amdgpu]
> __x64_sys_ioctl+0x81/0xb0
> do_syscall_64+0x34/0x80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> -> #0 (&process->mutex){+.+.}-{3:3}:
> __lock_acquire+0x1365/0x23d0
> lock_acquire+0xc9/0x2e0
> __mutex_lock+0xa4/0x940
> kfd_process_notifier_release+0x96/0xe0 [amdgpu]
> __mmu_notifier_release+0x94/0x210
> exit_mmap+0x35/0x1f0
> mmput+0x63/0x120
> svm_range_deferred_list_work+0x177/0x2c0 [amdgpu]
> process_one_work+0x2a4/0x600
> worker_thread+0x39/0x3e0
> kthread+0x16d/0x1a0
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock((work_completion)(&svms->deferred_list_work));
> lock(&info->lock#2);
> lock((work_completion)(&svms->deferred_list_work));
> lock(&process->mutex);
>
> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
> drivers/gpu/drm/amd/amdkfd/kfd_process.c | 21 +++++++++------------
> 1 file changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index fc38a4d81420..3c9cf9bdb63f 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -1115,6 +1115,15 @@ static void kfd_process_wq_release(struct work_struct *work)
> struct kfd_process *p = container_of(work, struct kfd_process,
> release_work);
>
> + kfd_process_dequeue_from_all_devices(p);
> + pqm_uninit(&p->pqm);
> +
> + /* Signal the eviction fence after user mode queues are
> + * destroyed. This allows any BOs to be freed without
> + * triggering pointless evictions or waiting for fences.
> + */
> + dma_fence_signal(p->ef);
> +
> kfd_process_remove_sysfs(p);
> kfd_iommu_unbind_process(p);
>
> @@ -1179,20 +1188,8 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn,
> cancel_delayed_work_sync(&p->eviction_work);
> cancel_delayed_work_sync(&p->restore_work);
>
> - mutex_lock(&p->mutex);
> -
> - kfd_process_dequeue_from_all_devices(p);
> - pqm_uninit(&p->pqm);
> -
> /* Indicate to other users that MM is no longer valid */
> p->mm = NULL;
> - /* Signal the eviction fence after user mode queues are
> - * destroyed. This allows any BOs to be freed without
> - * triggering pointless evictions or waiting for fences.
> - */
> - dma_fence_signal(p->ef);
> -
> - mutex_unlock(&p->mutex);
>
> mmu_notifier_put(&p->mmu_notifier);
> }
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