/srv/irclogs.ubuntu.com/2015/09/03/#ubuntu-kernel.txt

hallynapw: sforshee: so "recently" eric did the patches so that if you mount something over part of /proc, an unpriv user (in userns) can't uncover the mounted part.  can't umount the cover, can't mount a new instance02:54
hallyni didn't really think it was something people did...  more importantly it causes trouble for nested unprivileged containers.  since lxcfs files are mounted over procfiles, unpriv user can't then create a container02:56
hallynhow would you feel about a sysctl to turn that off?02:56
hallyn(it's done only for proc and sysfs near as i can tell)02:56
hallynmaybe i'll see how eric feels about that upstream02:57
hallynhm, though what i'm seeingdoesn't *really* make sense...03:00
hallynhm, maybe there should be an added check for sb equivalence03:06
hallynprobably doesn't make him feel as cozy...03:07
hallynheh, can't do that.  no sb yet03:11
hallynwell let's instrument for one more debug kernel03:22
stgraberhallyn: one thing that worries me there is that those fixes are in stable, so that effectively broke or will break all of our users... admitedly I'm probably the biggest user of userns nesting, but still, I can't be the only one.04:25
stgraberadding a sysctl may be fine, but we'd have to SRU a lxc packaging change to all supported releases to turn said sysctl on (and do so conditionally depending on kernel version as some won't have it)04:26
stgraberanyway, going to bed now04:26
=== gerald is now known as Guest25706
Tehdastehdas_I'm trying to report a kernel bug using "ubuntu-bug linux" as instructed in https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies . The first instruction after that is "The submitter should provide as much information as possible in the bug description". Where do I write this bug description? The first thing Apport asks me after launching it is "Send the report? | Cancel / Send"11:19
jpdsTehdastehdas_: That's after you send it11:21
Tehdastehdas_Oh11:21
Tehdastehdas_I wonder how many other users stopped there...11:23
tewardyou'd be surprised how many people run `ubuntu-bug` for other packages and just don't put information in either11:23
Tehdastehdas_maybe they have browser trouble11:24
Tehdastehdas_Success: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/149179711:35
ubot5Ubuntu bug 1491797 in linux (Ubuntu) "Shuts down when supposed to suspend as a reaction to self-caused overheat, session lost" [Undecided,New]11:35
jpdsTehdastehdas_: Did you configure the system to suspend on overheat?11:37
apwwe have a configuration option for that11:38
apwfrom what i can see the kernel is seeing the machine hit a critical temperature milestone and bailing to avoid dammage, that seems appropriate11:38
jpdsYeah, it doesn't sound like it's being "foolish"11:39
Tehdastehdas_But why not suspend as default?11:39
jpdsTehdastehdas_: I can't actually think of a situation where any of my machines have overheated11:40
Tehdastehdas_Sure, but just google "laptop overheating"11:40
jpdsAnd if it was a server room where the aircon failed... I'd rather the machines turned completely off really11:40
Tehdastehdas_How do I configure the system to suspend on overheat?11:41
Tehdastehdas_Also, how do I change the temperature limit, because sometimes bios crashes the machine first11:42
jpdsTehdastehdas_: Only reason I can think of where a laptop would overheat is a blocked fan?11:42
jpdsAt that point... you should clean the fan11:43
Tehdastehdas_Nope, the hardware has been disassembled, and everything was fine. Then I drilled extra holes to the bottom.11:43
apwTehdastehdas_, the temperature limits come from the bios tables iirc11:44
apwand normally the bios is in charge of the fans and the kernel just finds out about alerts from the bios11:44
Tehdastehdas_Using xsensors I can see that the fan runs 3500 rpm right before the crash, while maximum rpm is 500011:44
apwyep and the lenovo bios fan control has been criticised often in the older machines particularly for not spinning up quick enough11:45
Tehdastehdas_Another slow fan Lenovo bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/75168911:46
ubot5Ubuntu bug 751689 in linux (Ubuntu Precise) "[Lenovo Thinkpad x201s] Overheat due to slow fans when on 'auto'" [Critical,Confirmed]11:46
apwindeed cking (not here atm) did a very good write up of the issue, how the huristics in the bios fail to react fast enough11:46
Tehdastehdas_In my case the temperature can stay at 90 C for an hour, and the fan won't go faster than 3500 rpm11:47
Tehdastehdas_It's quiet though, that's nice11:48
Tehdastehdas_Soo, how about making the kernel throttle instead of overheat, and suspend at 97 C instead of shut down at 100 C?11:51
Tehdastehdas_by throttling I meant pausing processes to reduce heat production11:53
jpdsTehdastehdas_: Have you tried installing cpufrequtils and changing the governor of the CPUs?11:58
jpds(Not suggesting that that would solve the problem)11:59
apwTehdastehdas_, really it should not sit at that temp for a long time, ugg, those bios' are broke12:00
apwanyhow, i'll ask someone to have a peek later when they are on12:00
Tehdastehdas_yes, the bios is broken, but the kernel has many opportunities to remedy the situation, and it wastes them12:02
Tehdastehdas_I don't have the skills to trigger cpufrequtils at a certain temperature12:07
Tehdastehdas_Besides, that's the kernel's job in my opinion12:07
jpdsTehdastehdas_: It doesn't trigger, it runs the whole time12:10
Tehdastehdas_so it runs slowly all the time12:10
apwTehdastehdas_, the problem is the bios says to the kernel "do not do this i have it in hand", so the kernel goes about its business and later the bios says "OI YOU ITS TOO HOT STOP NOW" so it does12:11
Tehdastehdas_so the kernel should detect the faulty bios from the temperature/rpm -mismatch, and take control?12:13
apwi am not sure i can know in advance trivially, and once we get the "alert stop" i am not sure we can take control and switch to suspend12:14
apwthat said i thought that on these broken lenovos there was a lenovo specific fan control thing you could use12:14
apwwhich would take it out of auto, switching from bios to userspace control of the fans12:14
Tehdastehdas_I tried it a couple of years ago, but couldn't make it work, don't remember why12:17
Tehdastehdas_Surely it is the kernel's decision to shut down (and not suspend), as it logs the decision12:18
apwTehdastehdas_, not necessarily, that just means it got told it had to shutdown, that the bios said we are about to explode may mean we have no right to then ask the bios to suspend12:19
Tehdastehdas_hibernate then, that's not the bios's business?12:20
apwexcept that is a multi-second event we may not be give that long, i would think the contract with the bios is "stop, and make it quick else i will turn off under you"12:21
apwnot getting into this situation is better, and likely user control of fans is appropriate give this is patently a broken bios12:22
apwbut, anyhow, we had someone do a lot of work on this in the day, on an x201 iirc which that bug claims, and he ought to have the background on whats what12:22
Tehdastehdas_many seconds yes, as is shutting down12:23
apwTehdastehdas_, so ... i see in the bug you mentioned there is a suggestion to run thinkfan with a specific config, have you tried that at all?12:25
apwcomment #14112:26
Tehdastehdas_long time ago, didn't work, don't know why12:26
Tehdastehdas_still, I think it's the kernel's job, because users aren't that skilled12:27
apwif userspace can fix it, that can be automated such that it is simple for owners of the affected hw in all likleyhood12:28
apwthe kernel is not really the right place to handle such complex heuristics as they differ for each and every broken bios12:28
ogra_didnt the thermal handling switch to userspace with themald recently ? 12:28
apwand it would have a heap of junk that most people have12:28
apwogra_, a point indeed12:28
apwTehdastehdas_, what series are you running12:28
ogra_(at least for intel CPUs)12:28
apwogra_, it _is_ possible that that might be able to stave off doom in this case12:29
ogra_yeah12:29
ogra_or that thermald didnt get installed by update-manager 12:29
Tehdastehdas_series? is it not in the bug report?12:29
ogra_(which would be a serious update.manager bug indeed)12:30
Tehdastehdas_synaptic says thermald is not installed12:31
ogra_on what release are you ? 12:31
Tehdastehdas_14.0412:31
apwTehdastehdas_, it might be in the bug report, but it would have been easier to tell me than tell me its in the bug report12:31
ogra_iirc it is required from vivid on 12:31
ogra_ah12:31
apwok then the latest is available in vivid, as the linx-lts-vivid backport is there12:32
Tehdastehdas_but I don't recognize the word "series" in this context12:32
apwso ... i would suggest you try switching to the lts-vivid hwe kernel which will pull in and use thermald as well12:32
ogra_right, something in the hwe stack needs to pull it in apparently 12:32
apwsorry my bad, that is what launchpad calls a release12:32
apwTehdastehdas_, so like install linux-generic-lts-vivid and and then reboot, and see if things are any better12:33
apwTehdastehdas_, and if you do, regardless of whether it works, mention we suggested and your tried it, and what the result was12:34
Tehdastehdas_got it, rebooting12:38
Tehdastehdas_apw, installed it and rebooted - still max. 3500 rpm after several minutes at 95 C12:58
Tehdastehdas_am I supposed to add this information to the bug report?12:59
apwand cat /proc/version_signature says you have a 3.19 kernel and is thermald running12:59
apwand yes if you are running the new version and its there, writing that in the bug helps12:59
Tehdastehdas_it says Ubuntu 3.19.0-26.28~14.04.1-generic 3.19.8-ckt413:00
apwok thats good, so it is the new version13:00
apwps -ef | grep thermal13:00
apwdoes that say thermald is running13:00
Tehdastehdas_thermald --no-daemon --dbus-enable13:01
apwTehdastehdas_, ok record all that in the bug, and i'll ask someone to have a look when they are in13:08
Tehdastehdas_commented the bug report accordingly13:14
apwTehdastehdas_, thanks13:29
MikeCamelterrible newb qu: anyone got a good way to add a patched file to a source (dkms) deb file?  file-roller fail...19:29
FrauHaseHi19:33
MikeCamelHI19:33
FrauHaseIs there a chance to disable IPv4-support (for a IPv6-only network)?19:34
apwFrauHase, i'd say i normally just configure without ipv4 addresses19:35
apwwe have a coulpe of people who run ipv6 only networks, and things work modulo the internet not being very accessible v6 only19:35
stgraberyou can totally fix that by having your gateway do DNS64 and NAT64 for you19:36
apwstgraber, right but you need to be you to have the patience for all that19:36
FrauHaseactually, its for a test environment with no access to internet ... 19:36
apwbut it does work pretty well i think i heard you say19:36
stgraberthough then you'll still find a few random software (mostly perl) who don't even know what INET6 are and that will break (sent a dozen or so patches to various upstreams for that)19:36
stgraberand some things like google hangouts and my chromecast who are broken for different reasons (the first being some weird server-side bug on their end, the latter being because they don't bother to do IPv6 multicast)19:37
* apw watches stgraber take on the ipv6 world single handed :)19:38
FrauHaseguess I'll do as apw suggests ... just hoped for a more safe way to only have IPv6 talking on the net ...19:41
=== JanC_ is now known as JanC

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