Recently I had to switch to nouveau due to a problem with the official nvidia
drivers, and I have been experiencing ramdom gui freezes.

I usually can connect via ssh and reboot the machine.

lspci is:
01:00.0 VGA compatible controller: NVIDIA Corporation GF108 [GeForce GT 730]
(rev a1)                                            

The relevant logs I get are these:
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
...
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 7 kernel messages
Oct 12 12:16:43 phoenix kernel: PFIFO_READ/
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 6 kernel messages
Oct 12 12:16:43 phoenix kernel: BAR/PFIFO_READ/FB reason: PT_NOT_PRESENT
Oct 12 12:16:43 phoenix systemd-journal[395]: Missed 5 kernel messages
Oct 12 12:16:43 phoenix kernel: nouveau E[     PFB][0000:01:00.0] trapped read
at 0x0000005080 on channel 0x0007fed0 [unknown] BA
...