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.
It's possible that some of these issues are fixed with newer software, but ultimately I believe KDE likes to use multiple GL contexts from multiple threads at the same time, while nouveau does not like it when you do that. Until KDE started doing it, this was exceedingly rare. I believe they've since thrown wrenches into their internal logic to disable the threading, not sure.
Thanks for the comment, I'll setup another KDE Neon in virtualbox with the Nouveau driver, make sure I've still got the problem then wait for the latest KDE update and see if things have improved. For my main system (used for work) I need something stable so am using the Nvidia driver for the time being until things improve. I really like kmail and have used it for years so don't really want to switch to Thunderbird which I guess is a possible option for some.
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