Created attachment 132409 [details]
syslog output when kmail causes kmail/desktop to hang

System Config, KDE Neon LTS 5.8.7, Nouveau driver 1:1.0.12-2 as described by
Ubuntu 16.04.1 LTS. Nvidia GeForce GTX570M, kmail 5.5.2.

Kmail will become unresponsive when attempting to scroll or click left on an
email. Sometimes just the controls/buttons in kmail will be unreponsive but
sometimes the whole desktop will become unreponsive and freeze, requiring a
ALT-SYSRq RSEIUB command to reboot system, ALT-F1 not working. If instead I use
the Nvidia 375 driver the problem disappears, so this problem seems to be
related to the use of the Nouveau driver. syslog reports the following errors..


Jul  2 23:02:30 nick-X681X kernel: [12787.488155] nouveau 0000:01:00.0:
kmail[8229]: Unknown handle 0x0000002c
Jul  2 23:02:30 nick-X681X kernel: [12787.488159] nouveau 0000:01:00.0:
kmail[8229]: validate_init
Jul  2 23:02:30 nick-X681X kernel: [12787.488161] nouveau 0000:01:00.0:
kmail[8229]: validate: -2
Jul  2 23:02:33 nick-X681X kernel: [12790.327435] nouveau 0000:01:00.0: gr:
TRAP ch 17 [005f1f4000 kmail[8229]]
Jul  2 23:02:33 nick-X681X kernel: [12790.327448] nouveau 0000:01:00.0: gr:
GPC0/TPC0/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327456] nouveau 0000:01:00.0: gr:
GPC0/TPC1/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327464] nouveau 0000:01:00.0: gr:
GPC0/TPC2/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327472] nouveau 0000:01:00.0: gr:
GPC0/TPC3/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327481] nouveau 0000:01:00.0: gr:
GPC1/TPC0/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327489] nouveau 0000:01:00.0: gr:
GPC1/TPC1/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327498] nouveau 0000:01:00.0: gr:
GPC1/TPC2/TEX: 80000041
Jul  2 23:02:33 nick-X681X kernel: [12790.327513] nouveau 0000:01:00.0: fifo:
read fault at 0002a0a000 engine 00 [PGRAPH] client 01 [GPC1/TEX] reason 02
[PAGE_NOT_PRESENT] on channel 17 [005f1f4000 kmail[8229]]
Jul  2 23:02:33 nick-X681X kernel: [12790.327516] nouveau 0000:01:00.0: fifo:
gr engine fault on channel 17, recovering...
Jul  2 23:03:33 nick-X681X kernel: [12850.755747] nouveau 0000:01:00.0:
kmail[8229]: failed to idle channel 17 [kmail[8229]]
Jul  2 23:03:48 nick-X681X kernel: [12865.757800] nouveau 0000:01:00.0:
kmail[8229]: failed to idle channel 17 [kmail[8229]]

It also generates a second different error on some occasions ie a FIFO read
fault at 0001afa00 engine 00 [PGRAPH] client 01 [GPC1/TEX] reason 02 [Page not
present] on channel 5.

This error tends to hang the entire desktop, hence why I have attached a photo
of the tail -f /var/log/syslog output.