# CVE-2026-89753: mm/vmscan: report RCU-tasks quiescent states in shrink_lruvec()

> A missing RCU quiescent state report in Linux kernel memory reclaim can cause RCU stalls and system hangs, requiring a kernel patch.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100839, BELL-CVE-2026-89753, DEBIAN-CVE-2026-89753, GHSA-vf4v-9g5v-367g, UBUNTU-CVE-2026-89753

## What is CVE-2026-89753?

CVE-2026-89753 is a denial of service vulnerability in Linux, published on 11 Sep 2026. 

### Official description

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

mm/vmscan: report RCU-tasks quiescent states in shrink_lruvec()

I am seeing some rcu_tasks stalls in the Meta fleet during reclaim.

  INFO: rcu_tasks detected stalls on tasks:
	0000000088620d09: .. nvcsw: 6735/6735 holdout: 1 idle_cpu: -1/8
	task:GlobalCPUThread state:R  running task  pid:2552016 tgid:2524552
  Call Trace:
   shrink_lruvec
   mem_cgroup_iter
   shrink_node
   do_try_to_free_pages
   try_to_free_pages
   __alloc_frozen_pages_noprof
   alloc_pages_noprof
   pte_alloc_one
   __pte_alloc
   handle_mm_fault

Nothing promises direct reclaim returns in bounded time, and the scan loop
in shrink_lruvec() only calls cond_resched(), which is a no-op on
PREEMPTION kernels.  Involuntary preemption is not a Tasks-RCU quiescent
state, so the reclaiming task never reports one and becomes a holdout.

Upgrade it to cond_resched_tasks_rcu_qs(), which reports a quiescent state
even when cond_resched() does nothing.

PS: This has been discussed in [1]

## Which versions are affected by CVE-2026-89753?


## How do I fix CVE-2026-89753?

Apply the vendor's patch.

## Is CVE-2026-89753 being exploited?

There is no known exploitation of CVE-2026-89753 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89753 and fix it if it is affected.

What it is: CVE-2026-89753 is a denial of service vulnerability in Linux, published on 11 Sep 2026. 
Exploitation: There is no known exploitation of CVE-2026-89753 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-2026-89753/ (Markdown: https://insights.sbomify.com/CVE-2026-89753/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89753
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89753
- OSV: https://osv.dev/vulnerability/CVE-2026-89753

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89753/
Summaries are generated and may contain mistakes; the official description above is the record.