Ubuntu – After upgrade to Kubuntu 18.04, System wakes up immediately after suspend. Bug

18.04kernelsuspendwakeup

I recently upgraded to Kubuntu 18.04 (therefor to kernel 4.15.0-23).
I can't suspend my computer anymore. However, booting on a previous kernel version still lets me suspend my computer.

This is what exactly happens when I hit on 'Suspend':
System goes black, suspends (led blinking), awake by itself 1-2 seconds later.

Would you think there's an issue in the kernel? Is there any config/conflict issue ?

Thanks for your help!

Cheers,

Here are the logs:

journalctl -b | grep sleep

juil. 07 16:15:25 user-ubuntu NetworkManager[1016]: <info>  [1530972925.7995] manager: sleep: sleep requested (sleeping: no  enabled: yes)
juil. 07 16:15:25 user-ubuntu NetworkManager[1016]: <info>  [1530972925.7996] device (wlp2s0): state change: disconnected -> unmanaged (reason 'sleeping', sys-iface-state: 'managed')
juil. 07 16:15:26 user-ubuntu systemd-sleep[6022]: Suspending system...
juil. 07 16:15:31 user-ubuntu kernel: ACPI: Preparing to enter system sleep state S3
juil. 07 16:15:31 user-ubuntu kernel:  cache: parent cpu1 should not be sleeping
juil. 07 16:15:31 user-ubuntu kernel:  cache: parent cpu2 should not be sleeping
juil. 07 16:15:31 user-ubuntu kernel:  cache: parent cpu3 should not be sleeping
juil. 07 16:15:31 user-ubuntu kernel: ACPI: Waking up from system sleep state S3
juil. 07 16:15:31 user-ubuntu systemd-sleep[6022]: System resumed.
juil. 07 16:15:31 user-ubuntu systemd[1]: sleep.target: Unit not needed anymore. Stopping.
juil. 07 16:15:31 user-ubuntu systemd-logind[995]: Operation 'sleep' finished.
juil. 07 16:15:31 user-ubuntu NetworkManager[1016]: <info>  [1530972931.6845] manager: sleep: wake requested (sleeping: yes  enabled: yes)

journalctl -b | grep suspend

juil. 07 16:15:26 user-ubuntu kernel: PM: suspend entry (deep)
juil. 07 16:15:31 user-ubuntu kernel: Suspending console(s) (use no_console_suspend to debug)
juil. 07 16:15:31 user-ubuntu kernel: PM: suspend exit
juil. 07 16:15:31 user-ubuntu systemd[1]: suspend.target: Unit not needed anymore. Stopping.

Best Answer

Got it!

My USB wifi dongle seemed to wake my system up.

Step 1: check what is allowed to wake up your system:

Open a terminal:

sudo nano /proc/acpi/wakeup

Step 2: understand the results:

Screenshot of /proc/acpi/wakeup content - step 1

The list shows what device can awake your computer.

Here: EHC1 - EHC2 - XHC

Step 3: Block the device that wake up your computer:

Disable EHC1 in your terminal with:

echo EHC1 | sudo tee /proc/acpi/wakeup

Suspend your computer. If it still awakes, try

echo EHC2 | sudo tee /proc/acpi/wakeup

Note: EHC2 instead of EHC1. You can also try with XHC)

Note: above command is a kind of toggle. If you use it 2 times in a row, it will turn off EHC1, then turn it back on

Step 4: Confirm it worked

Here, it was EHC2 that woke up my computer (my USB wifi dongle). Now, it's disabled, it cannot awake my computer, and it stays suspended.

Screenshot of /proc/acpi/wakeup content - step 2

Related Solutions

Ubuntu – Kernel suspends too quickly, upon resume continues suspend tasks

After reviewing all the information I can find, I've come to the conclusion that you are affected by this kernel bug. which has affected numerous systems including Asus, Dell, HP, Lenovo, etc. This bug which will be marked for expiration in 47 days if no further activity occurs, is extremely hot, scoring 412 on the bug heat score and is reported as affecting 86 people at this moment. I recommend that you subscribe to it and provide any kernel related info that you can to help clarify the issue so that it remains open and the devs can squash it.

A likely workaround is upgrading/reverting to kernel 4.4.8 as noted here and confirmed here and here.

Work has been requested to reverse bisect the kernel but the bug is currently expired so it looks like the devs didn't get all the help they needed in determining the root cause of this behavior. Near as I can tell from perusing the bug report this problem appeared in kernel 4.4.0, was resolved in 4.4.8 and then reappeared sometime around 4.5.2 but I won't claim to be certain.

Another possible kernel upgrade workaround was reported here although I haven't found confirmation on that one.

If your using a kernel from the repository, it could be helpful if you were to launch ubuntu-bug linux from the terminal to create a new bug report providing specific information regarding your kernel/issue.

You might wish to rule out out-of-order-execution as a culprit as well. You should be able to accomplish this by disabling all but CPU0 like:

for x in /sys/devices/system/cpu/cpu*/online; do
  echo 0 >"$x"
done

You might also find this information useful in tracking down the root cause of this issue.

Sources:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1574125/

https://unix.stackexchange.com/questions/145645/disabling-cpu-cores-on-quad-core-processor-on-linux

Ubuntu – Ubuntu 18.04 error on waking up from sleep : Read-error on swap device

The Ubuntu 18.04 kernel you are currently using is missing a rather important bug fix.

The fix for this is already present in the upstream Linux kernel version 4.16.8. (The suspend bug effectively started happening in kernel version 4.15). Ubuntu only needs to cherry-pick this small patch from upstream. The bug frequently causes Xorg crashes immediately after suspend, i.e. it crashes the whole graphical login session.

Note this bug often happens without showing Read-error on swap device. Most of the time, there was no error in the kernel log. (A few times, it showed EXT4-fs error and Buffer I/O error instead). Also, these error messages could be caused by a hardware failure instead. When diagnosing this problem, please focus on other, more distinct details.

A test kernel is available at the end of this Ubuntu bug, i.e. in this comment: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1776887/comments/5

So far no-one has reported their results from suspending with the Ubuntu test kernel. ~~It might be that if someone can report success, it will encourage the Ubuntu developer to finally include the bug fix. I could be wrong though, I'm not 100% sure what's holding this up.~~

There is also a known workaround. You can avoid the crash if you configure the kernel command line to include the option scsi_mod.scan=sync.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1776887

This upstream bug has been confirmed to affect Ubuntu users[1]. As per the fix commit (below), the most frequent symptom is a crash of Xorg/Xwayland, i.e. killing the entire GUI, when a laptop is woken from system sleep. Frequency of the bug is described as once every few days[2].

[1] E.g. this user confirms the bug & very specific workaround: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1760450/comments/11

[2] E.g. this log of crashes: https://bugzilla.redhat.com/show_bug.cgi?id=1553979#c23

This is a bug in blk-core.c. It is not specific to any one hardware driver. Technically the suspend bug is triggered by the SCSI core - which is used by all SATA devices.

The commit also includes a test which quickly and reliably proves the existence of a horrifying bug.

I guess you might avoid this bug only if you have root on NVMe. The other way to not hit the Xorg crash is if you don't use all your RAM, so there's no pressure that leads to cold pages of Xorg being swapped. Also, you won't reproduce the Xorg crash if you suspend+resume immediately. (This frustrated my tests at one point, it only triggered after left the system suspended over lunch :).

Fix: "block: do not use interruptible wait anywhere"

in kernel 4.17: https://github.com/torvalds/linux/commit/1dc3039bc87ae7d19a990c3ee71cfd8a9068f428

in kernel 4.16.8: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.16.y&id=7859056bc73dea2c3714b00c83b253d4c22bf7b6

lack of fix in 4.15.0-24.26 (ubuntu 18.04): https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/tree/block/blk-core.c?id=Ubuntu-4.15.0-24.26#n856

I.e., this bug is still present in Ubuntu source package linux-4.15.0-24.26 (and 4.15.0-23.25). I attach hardware details (lspci-vnvn.log) of a system where this bug is known to happen.

Regards Alan

WORKAROUND: Use kernel parameter: scsi_mod.scan=sync

Best Answer

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