drm/amd/sched: fix deadlock caused by unsignaled fences of deleted jobs
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: [<ffffffffbc5e6722>] dma_fence_default_wait+0x112/0x250 [<ffffffffbc5e6399>] dma_fence_wait_timeout+0x39/0xf0 [<ffffffffbc5e82d2>] reservation_object_wait_timeout_rcu+0x1c2/0x300 [<ffffffffc03ce56f>] ttm_bo_cleanup_refs_and_unlock+0xff/0x1a0 [ttm] [<ffffffffc03cf1ea>] ttm_mem_evict_first+0xba/0x1a0 [ttm] [<ffffffffc03cf611>] ttm_bo_mem_space+0x341/0x4c0 [ttm] [<ffffffffc03cfc54>] ttm_bo_validate+0xd4/0x150 [ttm] [<ffffffffc03cffbd>] ttm_bo_init_reserved+0x2ed/0x420 [ttm] [<ffffffffc042f523>] amdgpu_bo_create_restricted+0x1f3/0x470 [amdgpu] [<ffffffffc042f9fa>] amdgpu_bo_create+0xda/0x220 [amdgpu] [<ffffffffc04349ea>] amdgpu_gem_object_create+0xaa/0x140 [amdgpu] [<ffffffffc0434f97>] amdgpu_gem_create_ioctl+0x97/0x120 [amdgpu] [<ffffffffc037ddba>] drm_ioctl+0x1fa/0x480 [drm] [<ffffffffc041904f>] amdgpu_drm_ioctl+0x4f/0x90 [amdgpu] [<ffffffffbc23db33>] do_vfs_ioctl+0xa3/0x5f0 [<ffffffffbc23e0f9>] SyS_ioctl+0x79/0x90 [<ffffffffbc864ffb>] entry_SYSCALL_64_fastpath+0x1e/0xad [<ffffffffffffffff>] 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 <nicolai.haehnle@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Reviewed-by: Andres Rodriguez <andresx7@gmail.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
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