# 21.04 with mainline kernel strange random "crash" not logged

**URL:** <https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038>\
**Category:** General\
**Created:** [June 7, 2021, 8:47am UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038 "2021-06-07T08:47:10Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![zilexa](https://avatars.discourse-cdn.com/v4/letter/z/bbe5ce/32.png) [@zilexa](https://discourse.ubuntubudgie.org/u/zilexa)\
**Post date:** [June 7, 2021, 8:47am UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/1 "2021-06-07T08:47:10Z")

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I am sure this is out of scope, but before I downgrade the kernel I would like to see if anyone can shed some light on this:

I have a Lenovo S540 IdeaPad, Ryzen 4800u. After installing clean 21.04, there were still some issues with the backlight buttons: whenever I change it, the screen becomes dark first. Minor issue. Also, on standby the battery drain is substantial (15% in 8 hours).

I read AMD has added improved Ryzen support to 5.12, so I updated to the latest non-rc: 5.12.8.

I didn’t really test 21.04, I immediately updated the kernel. Battery drain in standby is about 8% now, adjusting backlight works as expected. Bootlog only shows a few ACPI red warnings/errors.

Unfortunately, completely randomly, this happens:

1. my screen goes black for a second, Budgie UI homescreen is shown, all my open apps are no longer open. but my panel is white instead of black.
2. I create a screenshot but it cannot be saved anywhere, it seems /home is inaccessible.
3. After a few seconds more, see the second screenshot. This keeps scrolling non stop until I do a hard-shutdown with physical button.

 ![Screenshot_20210607-103315_Gallery](https://canada1.discourse-cdn.com/flex035/uploads/ubuntubudgie/original/2X/7/7877aa867219101ca268f045a257fdfafa1db097.jpeg)

 ![20210603_222256](https://canada1.discourse-cdn.com/flex035/uploads/ubuntubudgie/original/2X/e/e2cacaeb28c89b4c74d75f9f27a3d131e58d83cd.jpeg)

I assume this is related to me using a different kernel. It almost seems as if the (BTRFS) filesystem gets locked somehow. Not sure what triggers it.

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**Author:** ![fossfreedom](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.ubuntubudgie.org/fossfreedom/32/1405_2.png) [@fossfreedom](https://discourse.ubuntubudgie.org/u/fossfreedom)\
**Post date:** [June 7, 2021, 8:53am UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/2 "2021-06-07T08:53:19Z")

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Not sure on your specifics - but you maybe missing some firmware [https://bugs.launchpad.net/ubuntu/+source/linux-firmware/+bug/1922350](https://bugs.launchpad.net/ubuntu/+source/linux-firmware/+bug/1922350)

I’m waiting for this one to be resolved on my ryzen 7 series - brightness issues affects me.

Note - the above bug will only be fixed (when it comes) for the standard kernels - not the mainline.

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**Author:** ![zilexa](https://avatars.discourse-cdn.com/v4/letter/z/bbe5ce/32.png) [@zilexa](https://discourse.ubuntubudgie.org/u/zilexa)\
**Post date:** [June 7, 2021, 8:58am UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/3 "2021-06-07T08:58:11Z")

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I think I better stick with the standard kernel of 21.04 in that case and just be a little patient until an update presents itself 🙂

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**Author:** ![zilexa](https://avatars.discourse-cdn.com/v4/letter/z/bbe5ce/32.png) [@zilexa](https://discourse.ubuntubudgie.org/u/zilexa)\
**Post date:** [June 8, 2021, 6:22am UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/4 "2021-06-08T06:22:58Z")

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I first went back to the previous kernel, still had the same issue, screen flashes, Panel becomes white and no files can be read or written. I tried to open /var/log/syslog: input output error

When the journal stuff starts scrolling I can’t do much.

I did a clean 21.04 install… to my surprise that didn’t change a thing. I am going back to 20.10 now, as the issue didn’t show up with that version.

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**Author:** ![fossfreedom](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.ubuntubudgie.org/fossfreedom/32/1405_2.png) [@fossfreedom](https://discourse.ubuntubudgie.org/u/fossfreedom)\
**Post date:** [June 8, 2021, 6:56am UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/5 "2021-06-08T06:56:03Z")

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Is this because you are using btfrs? What happens if you use out of the box ext4?

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**Author:** ![zilexa](https://avatars.discourse-cdn.com/v4/letter/z/bbe5ce/32.png) [@zilexa](https://discourse.ubuntubudgie.org/u/zilexa)\
**Post date:** [June 8, 2021, 12:05pm UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/6 "2021-06-08T12:05:23Z")

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I always use btrfs since 20.04. Haven’t seen this issue before. But I think I found the culprit.  
By default, after installing Ubuntu-Budgie with btrfs filesystem, `/swapfile` is created. But since BTRFS does not allow a swapfile on a subvolume just like that (it could be snapshotted) and without CoW turned off, this will result in a warning/error and the swapfile will not be used. Most users won’t notice.

A few weeks ago I got an old Intel NUC with only 4GB RAM so I thought it would be wise to enable swap. I Googled and learned you have to create a seperate subvolume for it, mount it via fstab and apply `chattr +C` to disable CoW. So I did all that and it seems that system is working fine, while swapping.

I added these steps to my postinstall script that I run after a clean install, used it on my Ryzen laptop (with 16GB ram). When I used it, the issues began. Since I have cleaned up that post-install script a lot and made lots of modifications, I wasn’t sure what the issue could be. It seemed to be too low-level to be caused by my script.

Today, before switching back to 20.10 or testing ext4, I thought I simply do a quick clean install again and did not run my script → all goes fine!

Then I ran my script but omitted the swapfile commands → for over 40min now, all seems fine!

This is what I do to enable swap on btrfs:

```auto
# Temporarily mount filesystem root
sudo mount -o subvolid=5 /dev/nvme0n1p2 /mnt/system
# create a root subvolume for user personal folders in the root filesystem
sudo btrfs subvolume create /mnt/system/@swap
# Just to be sure, disable CoW for the subvolume
sudo chattr +C /mnt/system/@swap

# now umount the filesystem root
sudo umount /mnt/system

# Temporarily mount @swap and finish configuration 
sudo mkdir /swap
sudo mount -o subvol=@swap /dev/nvme0n1p2 /swap

# Configure swap file
sudo chattr +C /swap
sudo touch /swap/swapfile
sudo chattr +C /swap/swapfile
sudo chmod 600 /swap/swapfile
sudo dd if=/dev/zero of=/swap/swapfile bs=1024 count=4194304
sudo mkswap /swap/swapfile
sudo swapon /swap/swapfile

# Add mount rule to fstab
UUID=... /swap btrfs defaults,noatime,subvol=@swap 0 0
/swap/swapfile none swap sw 0 0

```

I can verify with `free -mh` and it shows 4GB swap.

I will wait for a day or so, play with the laptop a bit to ensure it works fine without swap, then I will try to enable swap again with the above commands.

It is a pity Ubuntu Installer doesn’t take care of this automatically when btrfs filesystem is selected, instead creating `/swapfile` that is broken/doesn’t work. Subvolumes `@` and `@home` are created by default the installer, it could create a subvolume `@swap` as well.

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<div class="post-metadata">

**Author:** ![fossfreedom](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.ubuntubudgie.org/fossfreedom/32/1405_2.png) [@fossfreedom](https://discourse.ubuntubudgie.org/u/fossfreedom)\
**Post date:** [June 8, 2021, 12:10pm UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/7 "2021-06-08T12:10:21Z")

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> [@zilexa](#):
>
> It is a pity Ubuntu Installer doesn’t take care of this automatically when btrfs filesystem is selected

Please do file a bug report against Ubiquity for this.

This way, the developers who are now creating the new installer are notified and can take this into account for the new installer - I’m assuming here the new installer offers btrfs as a filesystem of course.

You might also want to raise a query on the new installer github as well to see if they have immediate plans to offer btrfs - or if this is a future aspiration.

> **[GitHub - canonical/ubuntu-desktop-installer: Ubuntu Desktop Installer](https://github.com/canonical/ubuntu-desktop-installer)**
>
> Ubuntu Desktop Installer. Contribute to canonical/ubuntu-desktop-installer development by creating an account on GitHub.

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<div class="post-metadata">

**Author:** ![zilexa](https://avatars.discourse-cdn.com/v4/letter/z/bbe5ce/32.png) [@zilexa](https://discourse.ubuntubudgie.org/u/zilexa)\
**Post date:** [June 8, 2021, 5:20pm UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/8 "2021-06-08T17:20:20Z")

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Bad news, even after normal clean install without setting up swap myself, I get the same issue.

It is definitely BTRFS related. If I hit ESC and some other buttons and wait long enough:

 ![20210608_182610](https://canada1.discourse-cdn.com/flex035/uploads/ubuntubudgie/original/2X/e/e3cd99a871096ea9e9310c77cbc46300386fa8f8.jpeg)

Not sure how to report this as bug.

As suggested I did report the general issue with the old and the new installer regarding the creation a swapfile, but that can’t be the cause because this error happen on 20.04 and 20.10, same laptop, while installers from both prev versions also created a swapfile.

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<div class="post-metadata">

**Author:** ![fossfreedom](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.ubuntubudgie.org/fossfreedom/32/1405_2.png) [@fossfreedom](https://discourse.ubuntubudgie.org/u/fossfreedom)\
**Post date:** [June 8, 2021, 5:38pm UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/9 "2021-06-08T17:38:32Z")

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btrfs is a kernel issue

```
ubuntu-bug linux
```

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<div class="post-metadata">

**Author:** ![fossfreedom](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.ubuntubudgie.org/fossfreedom/32/1405_2.png) [@fossfreedom](https://discourse.ubuntubudgie.org/u/fossfreedom)\
**Post date:** [June 8, 2021, 6:09pm UTC](https://discourse.ubuntubudgie.org/t/21-04-with-mainline-kernel-strange-random-crash-not-logged/5038/10 "2021-06-08T18:09:30Z")

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Note though. Since you have reproduced this across multiple versions I feel it might just be worth double checking the health of your hard-drive. It might be failing and causing btfrs to go into read only mode trying to save your files from further corruption.