From 5c79e8d34f987f4fdddd6e152845f18d4aecbfde Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= Date: Thu, 28 Sep 2017 11:57:32 +0200 Subject: [PATCH 1961/4131] drm/amd/sched: fix deadlock caused by unsignaled fences of deleted jobs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Highly concurrent Piglit runs can trigger a race condition where a pending SDMA job on a buffer object is never executed because the corresponding process is killed (perhaps due to a crash). Since the job's fences were never signaled, the buffer object was effectively leaked. Worse, the buffer was stuck wherever it happened to be at the time, possibly in VRAM. The symptom was user space processes stuck in interruptible waits with kernel stacks like: [] dma_fence_default_wait+0x112/0x250 [] dma_fence_wait_timeout+0x39/0xf0 [] reservation_object_wait_timeout_rcu+0x1c2/0x300 [] ttm_bo_cleanup_refs_and_unlock+0xff/0x1a0 [ttm] [] ttm_mem_evict_first+0xba/0x1a0 [ttm] [] ttm_bo_mem_space+0x341/0x4c0 [ttm] [] ttm_bo_validate+0xd4/0x150 [ttm] [] ttm_bo_init_reserved+0x2ed/0x420 [ttm] [] amdgpu_bo_create_restricted+0x1f3/0x470 [amdgpu] [] amdgpu_bo_create+0xda/0x220 [amdgpu] [] amdgpu_gem_object_create+0xaa/0x140 [amdgpu] [] amdgpu_gem_create_ioctl+0x97/0x120 [amdgpu] [] drm_ioctl+0x1fa/0x480 [drm] [] amdgpu_drm_ioctl+0x4f/0x90 [amdgpu] [] do_vfs_ioctl+0xa3/0x5f0 [] SyS_ioctl+0x79/0x90 [] entry_SYSCALL_64_fastpath+0x1e/0xad [] 0xffffffffffffffff Note: The correctness of this change depends on the earlier commit "drm/amd/sched: move adding finish callback to amd_sched_job_begin" v2: set an error on the finished fence Signed-off-by: Nicolai Hähnle Reviewed-by: Christian König Reviewed-by: Andres Rodriguez Conflicts: drivers/gpu/drm/amd/scheduler/gpu_scheduler.c Change-Id: I5c0955c44a83db23bd74282e1ae6e0bfd6e71b93 --- drivers/gpu/drm/amd/scheduler/gpu_scheduler.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c index 4693be2..37e8b8d 100644 --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c @@ -227,9 +227,15 @@ void amd_sched_entity_fini(struct amd_gpu_scheduler *sched, */ kthread_park(sched->thread); kthread_unpark(sched->thread); - while (kfifo_out(&entity->job_queue, &job, sizeof(job))) + while (kfifo_out(&entity->job_queue, &job, sizeof(job))) { + struct amd_sched_fence *s_fence = job->s_fence; + amd_sched_fence_scheduled(s_fence); + dma_fence_set_error(&s_fence->finished, -ESRCH); + amd_sched_fence_finished(s_fence); + dma_fence_put(&s_fence->finished); sched->ops->free_job(job); - + } + } kfifo_free(&entity->job_queue); } -- 2.7.4