CVE-2021-46970

In the Linux kernel, the following vulnerability has been resolved: bus:
mhi: pci_generic: Remove WQ_MEM_RECLAIM flag from state workqueue A recent
change created a dedicated workqueue for the state-change work with
WQ_HIGHPRI (no strong reason for that) and WQ_MEM_RECLAIM flags, but the
state-change work (mhi_pm_st_worker) does not guarantee forward progress
under memory pressure, and will even wait on various memory allocations
when e.g. creating devices, loading firmware, etc… The work is then not
part of a memory reclaim path… Moreover, this causes a warning in
check_flush_dependency() since we end up in code that flushes a non-reclaim
workqueue: [ 40.969601] workqueue: WQ_MEM_RECLAIM
mhi_hiprio_wq:mhi_pm_st_worker [mhi] is flushing !WQ_MEM_RECLAIM
events_highpri:flush_backlog [ 40.969612] WARNING: CPU: 4 PID: 158 at
kernel/workqueue.c:2607 check_flush_dependency+0x11c/0x140 [ 40.969733]
Call Trace: [ 40.969740] __flush_work+0x97/0x1d0 [ 40.969745] ?
wake_up_process+0x15/0x20 [ 40.969749] ? insert_work+0x70/0x80 [ 40.969750]
? __queue_work+0x14a/0x3e0 [ 40.969753] flush_work+0x10/0x20 [ 40.969756]
rollback_registered_many+0x1c9/0x510 [ 40.969759]
unregister_netdevice_queue+0x94/0x120 [ 40.969761]
unregister_netdev+0x1d/0x30 [ 40.969765] mhi_net_remove+0x1a/0x40 [mhi_net]
[ 40.969770] mhi_driver_remove+0x124/0x250 [mhi] [ 40.969776]
device_release_driver_internal+0xf0/0x1d0 [ 40.969778]
device_release_driver+0x12/0x20 [ 40.969782] bus_remove_device+0xe1/0x150 [
40.969786] device_del+0x17b/0x3e0 [ 40.969791]
mhi_destroy_device+0x9a/0x100 [mhi] [ 40.969796] ?
mhi_unmap_single_use_bb+0x50/0x50 [mhi] [ 40.969799]
device_for_each_child+0x5e/0xa0 [ 40.969804] mhi_pm_st_worker+0x921/0xf50
[mhi]