/srv/irclogs.ubuntu.com/2018/01/12/#ubuntu-kernel.txt

tsimonq2.ir00:00
tsimonq2whoops00:00
threshjsalisbury, thank you.  I wont be able to test them until this Sunday, sadly.05:32
tomreyngood morning. do yuo think this https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1690085 and the linked kernel.org bug are actually the same? i would think they are actually unrelated issues.06:12
ubot5Launchpad bug 1690085 in linux (Ubuntu) "Ryzen 1800X freeze - rcu_sched detected stalls on CPUs/tasks" [High,Confirmed]06:12
tomreynalso, do you think the ubuntu bug could be ubuntu specific, or could be worked around in ubuntu? the workaround discussed in this bug report seems reliable to me.06:13
tomreynin my experience diabling ALSR is not necessary, and i would think CONFIG_RCU_NOCB_CPU is an acceptable compromise (for this cpou type)06:16
tomreyngot disconnected, so i'll type it again:06:25
tomreyngood morning. do yuo think this https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1690085 and the linked kernel.org bug are actually the same? i would think they are actually unrelated issues because one of these occurs only in high load (bugzilla.linux.org), the other only in low load (bugs.launchpad.net) situations.06:26
ubot5Launchpad bug 1690085 in linux (Ubuntu) "Ryzen 1800X freeze - rcu_sched detected stalls on CPUs/tasks" [High,Confirmed]06:26
tomreynalso, do you think the ubuntu bug could be ubuntu specific, or could be worked around in ubuntu? the workaround discussed in this bug report seems reliable to me.06:26
tomreynin my experience diabling ALSR is not necessary, and i would think CONFIG_RCU_NOCB_CPU is an acceptable compromise (for this cpou type)06:26
alkisgOn 16.04 a school reports that it cannot boot with vmlinuz-4.13.0-26-generic, is there an even newer kernel that they could try?08:44
apwalkisg, there is a -28, but i would be supprised if that sorts any boot issues, not impossible, but supprising08:53
alkisgapw, thank you... I'll also try with some from the mainline then08:54
=== himcesjf_ is now known as him-cesjf
apwalkisg, do you get anything other than reports of "doesn't boot", and sort of diagnostics someone might be able to look at ?08:55
alkisgapw: unfortunately the school IT teachers don't have a lot of linux exprertise, so I would have to travel there (e.g. half an hour drive) and do it myself... I'm doing that of course when the need is great, but usually not when an easy workaround exists08:57
apwalkisg, we have never (as a linux community) entirely sensible about making the diagnostics easy for an end-user to report08:58
apwalkisg, we did (in the pub over beer) talk about encoding panic stacks as QR codes and showing those08:58
alkisgI have set up a very easy way for user-initiated vnc access, but of course that part only works when it boots08:58
alkisgI've also worked once with a kvm/ip switch that gave me remote access even before the computer boots, but it's too costly for wide deployment08:59
alkisgQR codes sound amazing08:59
alkisgAnother trick I'm using is: "boot from a live cd. apt install x11vnc kvm; x11vnc -connect srv1-dide.ioa.sch.gr; kvm -m 1024 /dev/sda"09:01
alkisgSo if they can boot from a live cd and the problem is reproducible under kvm, I can see it remotely09:01
apwlike that one09:02
f_galkisg: what was the last kernel which did boot? 4.13 has a bug with some SCSI controllers that panic on b oot09:32
alkisgf_g: the 4.10.something kernel that 16.04 had09:32
alkisg(before the 4.13 bump)09:32
f_gas do 4.12, 4.14 and I think 4.15. I saw some patches flying around on LKML that might solve it, Debian's 4.9 and our downstream 4.13 just reverted the buggy commit for now09:33
alkisgI can get the exact number if needed09:33
alkisg 4.10.0-42 afaik09:33
f_galkisg: see https://bugs.launchpad.net/ubuntu/+source/linux/+bug/172651909:35
ubot5Launchpad bug 1726519 in linux (Ubuntu Bionic) "Unable to handle kernel NULL pointer dereference at isci_task_abort_task" [High,In progress]09:35
f_gmost systems failing to boot 4.13 that I have seen were that one09:36
f_gand a simple revert fixes it09:36
f_gjust added the likely upstream fix as well as a comment, but AFAICT it has not been merged upstream yet.09:39
f_ghttps://patchwork.kernel.org/patch/10154587/ in case you want to test it yourself ;)09:39
f_galkisg jsalisbury ^^09:40
alkisgf_g: thanks, that would explain why I can't reproduce it in a VM09:55
f_galkisg: it's entirely possible it's some other HW-related issue though. but if you need to go there to investigate, I'd recommend having a build with the cherry-pick and one with the revert handy to test :P10:29
f_gthe Spectre/IBRS/IBPB commits in the pti branch have been picked from upstream's pti tip? or straight from LKML? or ... ?11:18
apwthey are patches we receieved from Intel, they are not likely the final solution11:58
f_gapw: thanks for the info. it seems like the first round is getting finalized for upstream inclusion and might make it into -rc8, if it does will you rebase the non-s390 stuff to match what lands upstream?12:20
apwf_g, will have to see what lands, if it is reptoline without ibrs (which i assume it is) it will depend how hard it is to merge them, as upstram will put ibrs on the top next12:21
apwf_g, in large part it is effort and risk against timescales 12:22
f_gtip/pti is currently retpoline only12:23
apwright, and there is some concern that reptoline in its current form is not sufficient, so we ahve to err on the side of safe and slow12:24
apwwe are following along, and assuming we will go that way as soon as humanly sensible12:24
f_gright. thanks!12:25
apwthough google appears to be of the opinion the westmere escapes are highly unlikely, and likely can be fixed by improving reptoline ...12:26
jsalisburyf_g, alkisg I built a test kernel with the patch posted here:12:48
jsalisburyhttps://marc.info/?l=linux-scsi&m=15155732490791412:48
jsalisburyThe test kernel can be downloaded from:12:48
jsalisburyhttp://kernel.ubuntu.com/~jsalisbury/lp174263012:48
jsalisburyCan you test this kernel and see if it resolves this bug?12:48
=== Trevinho_ is now known as Trevinho
gpiccoliHi, I was reading: https://help.ubuntu.com/community/UbuntuStudio/RealTimeKernel14:07
gpiccoliIt shows a table with multiple flavours of kernel, like -lowlatency, -rt and -generic. Thne it mentions "the first 3 above are provided through official Ubutu archives", meaning -generic, -preempt and -rt14:08
gpiccoliI could only find -generic and -lowlatency though; is the information obsolete?14:09
gpiccoliIt could be edited in order to be more accurate, if it's the case.14:09
gpiccolitnx in advance for any clarification!14:09
alkisgjsalisbury: I don't have any amd64 school installation to test with, they're all i386... :/14:10
jsalisburyalkisg, I'll build a 32 bit kernel for you and let you know when it's ready.14:15
alkisgjsalisbury: thank you14:15
alkisgI'll go to the school and test on Monday then, when it opens14:16
jsalisburyalkisg, There is an i386 version of the test kernel available now.  It can be downloaded from:15:19
jsalisburyhttp://kernel.ubuntu.com/~jsalisbury/lp1742630/i38615:19
alkisgjsalisbury: thank you, I can test this on Monday15:19
jsalisburyalkisg, great, thanks!15:20
VulcanRidrQuick question. I have noticed in the recent past that kernel upgrades do not seem to be writing a /run/reboot-required. Is this an intentional thing? Is there a new method of knowing the system needs a reboot? I'm working mostly on 14.04 boxes.16:55
TJ-VulcanRidr: is unattended-upgrades package installed?17:01
VulcanRidrTJ-: It is.17:01
VulcanRidrroot@unkarplutt:~# ls -l /run/reboot-required17:04
VulcanRidrls: cannot access /run/reboot-required: No such file or directory17:04
VulcanRidrroot@unkarplutt:~# dpkg -l unattended-upgrades17:04
VulcanRidrDesired=Unknown/Install/Remove/Purge/Hold17:04
VulcanRidr| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend17:04
VulcanRidr|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)17:04
VulcanRidr||/ Name           Version      Architecture Description17:04
VulcanRidr+++-==============-============-============-==================================17:04
VulcanRidrii  unattended-upg 0.82.1ubuntu all          automatic installation of security17:04
TJ-VulcanRidr: hmmm, because for u-u that marker file is touched by the script /etc/kernel/postinst.d/unattended-upgrades17:06
VulcanRidrHrmmm...So where did that file go?17:08
TJ-VulcanRidr: is it missing ?17:08
TJ-do "dpkg -L unattended-upgrades" check if it is in the 14.04 package; I checked on 16.0417:09
VulcanRidrTJ-: It sure isn't in there.17:15
VulcanRidrThat explains a lot...17:15
VulcanRidrIt is on the 16.04 box I checked, but it is certainly not on the 14.04 box.17:17

Generated by irclog2html.py 2.7 by Marius Gedminas - find it at mg.pov.lt!