# CVE-2026-89566: jbd2: check need_resched() when skipping busy checkpoint buffers

> A flaw in the Linux kernel's jbd2 journaling code can cause soft lockups or RCU stalls under memory pressure, leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-100688, BELL-CVE-2026-89566, DEBIAN-CVE-2026-89566, GHSA-p6jx-2fv3-6j26, UBUNTU-CVE-2026-89566

## What is CVE-2026-89566?

CVE-2026-89566 is a denial of service vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

jbd2: check need_resched() when skipping busy checkpoint buffers

journal_shrink_one_cp_list() skips busy checkpoint buffers when called
with JBD2_SHRINK_BUSY_SKIP.  The continue statement on this path also
skips the need_resched() check at the end of the loop body.

Consequently, when a checkpoint list contains mostly busy buffers, the
shrinker can walk the entire list while holding journal->j_list_lock,
even when a reschedule has been requested.  Large checkpoint lists under
memory pressure can therefore cause long lock hold times and leave other
CPUs spinning on j_list_lock, resulting in soft lockups or RCU stalls.

Route the busy-buffer path through the need_resched() check so that the
shrinker can release j_list_lock and reschedule promptly, restoring
parity with the clean-buffer path, which already checks need_resched().
This does not change which checkpoint buffers are eligible for removal.

## Which versions are affected by CVE-2026-89566?


## How do I fix CVE-2026-89566?

Apply the vendor's patch.

## Is CVE-2026-89566 being exploited?

There is no known exploitation of CVE-2026-89566 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89566 and fix it if it is affected.

What it is: CVE-2026-89566 is a denial of service vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-89566 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89566/ (Markdown: https://insights.sbomify.com/CVE-2026-89566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89566
- OSV: https://osv.dev/vulnerability/CVE-2026-89566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89566/
Summaries are generated and may contain mistakes; the official description above is the record.