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dawnofman

Member

Registered: 2019-07-26

Posts: 140

[solved] custom-built ZFS packages taints the kernel upon loading

I just built and installed the ZFS 2.1.4-1 (against kernel 5.17.5) package myself after the zfs-linux and zfs-tools packages on the AUR and everything fine so far ... but:

modprobe zfs; ### to load the ZFS modules

lsmod;

zfs                  3936256  0
zunicode              335872  1 zfs
zzstd                 585728  1 zfs
zlua                  184320  1 zfs
zavl                   16384  1 zfs
icp                   327680  1 zfs
zcommon               102400  2 zfs,icp
znvpair               106496  2 zfs,zcommon
spl                   118784  6 zfs,icp,zzstd,znvpair,zcommon,zavl

journalctl --boot;
...
2022-05-01T00:33:14.710878-0300 noname kernel: spl: loading out-of-tree module taints kernel.
2022-05-01T00:33:14.711948-0300 noname kernel: spl: module verification failed: signature and/or required key missing - tainting kernel
2022-05-01T00:33:14.714204-0300 noname kernel: znvpair: module license 'CDDL' taints kernel.
2022-05-01T00:33:14.714305-0300 noname kernel: Disabling lock debugging due to kernel taint
2022-05-01T00:33:14.914229-0300 noname kernel: ZFS: Loaded module v2.1.4-1, ZFS pool version 5000, ZFS filesystem version 5

It taints the kernel ... is this normal for ZFS ?

EDIT: Adding some info after reading tainted kernels:

cat /proc/sys/kernel/tainted;
12289

for i in $(seq 18); do echo $(($i-1)) $(($(cat /proc/sys/kernel/tainted)>>($i-1)&1));done
0 1
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
10 0
11 0
12 1
13 1
14 0
15 0
16 0
17 0

So it is tainted because; either:

- 0 G/P 1 proprietary module was loaded
- 12 _/O 4096 externally-built (“out-of-tree”) module was loaded
- 13 _/E 8192 unsigned module was loaded

Quoting the above URL (bold text mine):

The kernel will mark itself as ‘tainted’ when something occurs that might be relevant later when investigating problems. Don’t worry too much about this, most of the time it’s not a problem to run a tainted kernel; the information is mainly of interest once someone wants to investigate some problem, as its real cause might be the event that got the kernel tainted. That’s why bug reports from tainted kernels will often be ignored by developers, hence try to reproduce problems with an untainted kernel.

Last edited by dawnofman (2022-05-02 02:01:32)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,285

Re: [solved] custom-built ZFS packages taints the kernel upon loading

Yes external modules  taint the kernel. The main thing this means for you as an user that you can generally not expect to receive support for a bug you have with a tainted kernel should you report on bugzilla.kernel.org

dawnofman

Member

Registered: 2019-07-26

Posts: 140

Re: [solved] custom-built ZFS packages taints the kernel upon loading

Yes external modules  taint the kernel. The main thing this means for you as an user that you can generally not expect to receive support for a bug you have with a tainted kernel should you report on bugzilla.kernel.org

Thanks for your clarification V1del.

Yes, I have already read the mention to not expect support from a tainted kernel.

Now let me gasp this for a minute: does this implies that everyone running ZFS out there ... are running tainted kernels then ?

Something like becoming second-class citizens when running ZFS on linux due to the taint -> unsupported issue ? (A)

In one of my previous posts, systemd-udevd:# blocked for more than # seconds ... meaning ?, someone asked me why I was running a tainted kernel and at the time I did have not the slightest idea of what a tainted kernel was. But I was running the same custom-built ZFS package, 0.8.1 back then. Now I realize that the taint in the kernel was triggered by the ZFS modules.

(A) What about ZFS as DKMS ?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,285

Re: [solved] custom-built ZFS packages taints the kernel upon loading

DKMS has no effect on any of these. DKMS just automates the build process for a given kernel, you build the same final result, which has the same stipulation as the "pre-compiled" module.

In terms of upstream kernel development you'll be a "second class citizen" but as long as the actual ZFS maintainers are maintaining the patch set you will have people doing the work and you could technically get someone with an untainted kernel to verify bugs that are outside of the filesystem for any other issues that may come up.

Last edited by V1del (2022-05-01 16:24:37)

dawnofman

Member

Registered: 2019-07-26

Posts: 140

Re: [solved] custom-built ZFS packages taints the kernel upon loading

DKMS has no effect on any of these. DKMS just automates the build process for a given kernel, you build the same final result, which has the same stipulation as the "pre-compiled" module.

In terms of upstream kernel development you'll be a "second class citizen" but as long as the actual ZFS maintainers are maintaining the patch set you will have people doing the work and you could technically get someone with an untainted kernel to verify bugs that are outside of the filesystem for any other issues that may come up.

Understood. Thanks for your reply and the clarification V1del.