kern/56868: nouveau kills fifo channel, X server crashes

[mrg%eterna.com.au@localhost]

>Number:         56868
>Category:       kern
>Synopsis:       nouveau kills fifo channel, X server crashes
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 07 05:55:01 +0000 2022
>Originator:     matthew green
>Release:        NetBSD 9.99.97
>Organization:
people's front against (bozotic) www (softwar foundation)
>Environment:
Machine: amd64
>Description:

	twice with a nvidia geforce 730 i've had X server crash after some
	uptime (several days).

	the kernel messages from this time:

   nouveau0: autoconfiguration error: error: gr: TRAP ch 2 [007fb82000 user]
   nouveau0: autoconfiguration error: error: gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 2000e [OOR_ADDR]
   nouveau0: autoconfiguration error: error: gr: TRAP ch 2 [007fb82000 user]
   nouveau0: autoconfiguration error: error: gr: GPC0/TPC0/MP trap: global 00000000 [] warp 3f0009 [ILLEGAL_INSTR_ENCODING]
   nouveau0: autoconfiguration error: error: gr: TRAP ch 2 [007fb82000 user]
   nouveau0: autoconfiguration error: error: gr: GPC0/TPC0/MP trap: global 00000004 [MULTIPLE_WARP_ERRORS] warp 000e [OOR_ADDR]
   nouveau0: autoconfiguration error: error: fifo: fault 00 [READ] at 0000000005392000 engine 00 [GR] client 01 [GPC0/T1_0] reason 02 [PTE] on channel 2 [007fb82000 user]
   nouveau0: notice: fifo: channel 2: killed
   nouveau0: warn: user: channel 2 killed!
   nouveau0: notice: fifo: runlist 0: scheduled for recovery
   nouveau0: notice: fifo: engine 0: scheduled for recovery
   nouveau0: autoconfiguration error: error: gr: TRAP ch 2 [007fb82000 user]
   nouveau0: autoconfiguration error: error: gr: GPC0/TPC0/TEX: 80000041

the Xorg log file has nothing useful from the crash moment, but the
console has some messages not in the log:

   nouveau: kernel rejected pushbuf: Operation not supported by device
   nouveau: ch2: kref 0 pushes 1 bufs 10 relocs 0
   [ ... larger log here i have pictures of is necessary .. ]
   assertion "kref" failed: file ".../libdrm/dist/nouveau/pushbuf.c", line 730, ...

>How-To-Repeat:
	
	use nouveau in -current with a GT 730.

>Fix: