In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/userq: fix indefinite fence wait during GPU reset
pre_reset only force-completes fences of MAPPED queues. A queue in any
other state (e.g. mid-eviction) keeps its last_fence pending; after a
GPU reset that fence never signals, so the eviction/suspend worker and
process teardown (amdgpu_evf_mgr_flush_suspend) wait on it forever and
wedge the machine:
INFO: task kworker/6:28 blocked for more than 120 seconds.
Workqueue: events amdgpu_eviction_fence_suspend_worker [amdgpu]
Call Trace:
dma_fence_wait_timeout+0x7e/0x130
amdgpu_userq_evict+0x67/0x140 [amdgpu]
amdgpu_eviction_fence_suspend_worker+0xd8/0x160 [amdgpu]
process_scheduled_works+0xa6/0x420
Force-complete every queue's fence regardless of state. The unmap and
mark-hung step stays gated on MAPPED, since unmapping a queue that is
not mapped is invalid.
(cherry picked from commit 9102b39fa924dcc3dc75a3137bfa9633c40b88c0)