collector: add tainted collector for /proc/sys/kernel/tainted by arunsrini3082 · Pull Request #3745 · prometheus/node_exporter

arunsrini3082 · 2026-07-15T07:43:12Z

Summary

Add a tainted collector that exposes kernel taint flags from
/proc/sys/kernel/tainted as Prometheus metrics.

This revives the idea originally proposed in #1567. The review feedback
from that PR has been addressed:

Parsing is moved to the prometheus/procfs library (companion PR:
procfs: add KernelTainted() to parse /proc/sys/kernel/tainted procfs#844)
Metric uses labels instead of one metric per bit:
node_kernel_tainted{bit="14", flag="L"} 1

Metrics

node_kernel_tainted{bit="14", flag="L"} 0
node_kernel_tainted{bit="12", flag="O"} 1

One series per known taint bit (20 total), value 0 or 1.
Disabled by default — enable with --collector.tainted.

Dependencies

⚠️ This PR depends on prometheus/procfs#844 being merged first.
The go.mod procfs version will be bumped before merging once
that PR is released.

Reference

https://www.kernel.org/doc/html/latest/admin-guide/tainted-kernels.html

arunsrini3082 · 2026-07-18T07:32:24Z

Both procfs PRs are now merged:

#844 — KernelTainted() implementation
#847 — fix linux build tag (was !windows, caused crossbuild failures on OpenBSD/NetBSD/DragonFly/Solaris)

No new procfs release has been cut yet, so I've temporarily pinned go.mod to the merged commit pseudo-version to unblock CI. Will update to the proper release tag once available.

arunsrini3082 · 2026-07-28T10:41:52Z

Built and tested in our environment. All 20 taint flags are correctly exposed:

vasudeva.sk:~/kernel_taints$ curl -s 0:9100/metrics | grep node_kernel_tainted
# HELP node_kernel_tainted Taint flags set on the running Linux kernel, as reported by /proc/sys/kernel/tainted. Value is 1 if the flag is set, 0 otherwise. See https://www.kernel.org/doc/html/latest/admin-guide/tainted-kernels.html for flag meanings.
# TYPE node_kernel_tainted gauge
node_kernel_tainted{bit="0",flag="P"} 0
node_kernel_tainted{bit="1",flag="F"} 0
node_kernel_tainted{bit="2",flag="S"} 0
node_kernel_tainted{bit="3",flag="R"} 0
node_kernel_tainted{bit="4",flag="M"} 0
node_kernel_tainted{bit="5",flag="B"} 0
node_kernel_tainted{bit="6",flag="U"} 0
node_kernel_tainted{bit="7",flag="D"} 0
node_kernel_tainted{bit="8",flag="A"} 0
node_kernel_tainted{bit="9",flag="W"} 0
node_kernel_tainted{bit="10",flag="C"} 0
node_kernel_tainted{bit="11",flag="I"} 0
node_kernel_tainted{bit="12",flag="O"} 0
node_kernel_tainted{bit="13",flag="E"} 0
node_kernel_tainted{bit="14",flag="L"} 0
node_kernel_tainted{bit="15",flag="K"} 0
node_kernel_tainted{bit="16",flag="X"} 0
node_kernel_tainted{bit="17",flag="T"} 0
node_kernel_tainted{bit="18",flag="N"} 0
node_kernel_tainted{bit="19",flag="J"} 0

This is on a clean kernel (all flags 0). The collector is working as expected.

nicolastakashi · 2026-08-07T15:11:29Z

 	github.com/prometheus/common v0.70.0
 	github.com/prometheus/exporter-toolkit v0.17.1
-	github.com/prometheus/procfs v0.21.1
+	github.com/prometheus/procfs v0.21.2-0.20260717070424-0cd18237af6e


blocking: this pins procfs to an untagged pseudo-version (v0.21.2-0.20260717070424-0cd18237af6e). Rebase onto master and point to a tagged release once one includes #844/#847. Can't merge on an untagged commit.

Waiting on procfs release for #844/#847; will update go.mod once tagged.

arunsrini3082 · 2026-08-08T06:07:48Z

Blocked on a tagged procfs release for KernelTainted() (#844) and the linux build-tag fix (#847).

Tracking: prometheus/procfs#859

Will update go.mod to the tagged release once published.

nicolastakashi · 2026-08-15T20:03:17Z

@arunsrini3082 can you check failing ci?

arunsrini3082 · 2026-08-16T06:22:18Z

@arunsrini3082 can you check failing ci?

Only DragonFly fails, and it fails at the dependency installation step (sudo exit code 100) before any tests run. FreeBSD, OpenBSD, NetBSD, Solaris, and Darwin/MacOS all pass. This is a DragonFly VM runner issue on AnyVM.org, not related to this PR. The tainted collector has //go:build linux so it doesn't affect any BSD target anyway.

ArthurSens

Looks like documentation is missing in our README, could you add it to the list?

And looks like we're still waiting for the procfs release 😬

arunsrini3082 · 2026-08-22T13:31:06Z

Looks like documentation is missing in our README, could you add it to the list?

And looks like we're still waiting for the procfs release 😬

Review feedback addressed: procfs.FS cached on collector, matching !notainted build tag, README updated for node_kernel_tainted.

Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

Co-authored-by: Cursor <cursoragent@cursor.com> Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

Store procfs.FS on the collector instead of opening it each scrape. Add matching !notainted build tag on the implementation file. Document the tainted collector and node_kernel_tainted metrics in README. Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

ArthurSens

whoops, I forgot to add the comment in the previous review

Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

ArthurSens

LGTM, we just need a procfs release now :)

dongjiang1989 · 2026-09-04T07:19:29Z

procfs release v0.22.0. @arunsrini3082 Please rebase it

Signed-off-by: Arun Srinivasan <arunpiter@gmail.com>

Fixes build and BSD e2e failures caused by stale dependency versions left over from a bad merge. Signed-off-by: Arun S <arun.srinivasan@flipkart.com> Co-authored-by: Cursor <cursoragent@cursor.com>

arunsrini3082 · 2026-09-04T09:26:41Z

procfs release v0.22.0. @arunsrini3082 Please rebase it

Thanks. and it's up for the review. Please do the needful.

@ArthurSens @dongjiang1989 @nicolastakashi

ArthurSens · 2026-10-15T17:46:17Z

Thanks and sorry for dropping the ball on this one!

arunsrini3082 force-pushed the kernel-tainted branch from cc89def to fca75e8 Compare July 16, 2026 06:01

nicolastakashi reviewed Aug 7, 2026

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arunsrini3082 mentioned this pull request Aug 8, 2026

Release request: tag v0.21.2 (includes KernelTainted from #844/#847) prometheus/procfs#859

Closed

arunsrini3082 force-pushed the kernel-tainted branch from ffe6a29 to b26e9a2 Compare August 9, 2026 15:54

arunsrini3082 requested a review from nicolastakashi August 21, 2026 05:18

nicolastakashi approved these changes Aug 21, 2026

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ArthurSens reviewed Aug 22, 2026

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Comment thread collector/tainted_linux.go Outdated

Comment thread collector/tainted_linux_test.go

Arun S and others added 5 commits August 22, 2026 19:02

collector: add tainted collector for /proc/sys/kernel/tainted

8ec12fa

Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

go.mod: bump procfs to pick up KernelTainted() (prometheus#844)

72962a5

Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

go.mod: bump procfs to pick up linux build tag fix (prometheus#847)

19cd78d

Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

collector/tainted: use year-less copyright header

7747d62

Co-authored-by: Cursor <cursoragent@cursor.com> Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

arunsrini3082 force-pushed the kernel-tainted branch from 0d9a365 to f6a97bb Compare August 22, 2026 13:33

ArthurSens requested changes Aug 22, 2026

View reviewed changes

ArthurSens reviewed Aug 22, 2026

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Comment thread README.md Outdated

README: drop tainted collector section, keep table entry only

70a06b1

Signed-off-by: Arun S <arun.srinivasan@flipkart.com>

arunsrini3082 requested a review from ArthurSens August 23, 2026 02:54

ArthurSens approved these changes Aug 25, 2026

View reviewed changes

arunsrini3082 and others added 2 commits September 4, 2026 14:34

Merge branch 'master' into kernel-tainted

a8b67d8

Signed-off-by: Arun Srinivasan <arunpiter@gmail.com>

go.mod: align with master after merge (procfs v0.22.0, toolkit v0.19.0)

422f8bc

Fixes build and BSD e2e failures caused by stale dependency versions left over from a bad merge. Signed-off-by: Arun S <arun.srinivasan@flipkart.com> Co-authored-by: Cursor <cursoragent@cursor.com>

arunsrini3082 added 2 commits September 22, 2026 10:34

Merge branch 'master' into kernel-tainted

060078a

Merge branch 'master' into kernel-tainted

75996c1

ArthurSens merged commit 37ec35f into prometheus:master Oct 15, 2026
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arunsrini3082 commented Jul 15, 2026

Summary

Metrics

Dependencies

Reference

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