# CVE-2026-89986: mm/mempolicy: fix sleeping allocation in alloc_pages_bulk_weighted_interleave()

> A kernel bug causes a sleeping allocation in atomic context, leading to system crashes or instability when specific memory policies are active.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-89986, DEBIAN-CVE-2026-89986, GHSA-f5rq-g72v-q29m, UBUNTU-CVE-2026-89986

## What is CVE-2026-89986?

CVE-2026-89986 is a high-severity denial of service vulnerability in Linux, published on 16 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:

mm/mempolicy: fix sleeping allocation in alloc_pages_bulk_weighted_interleave()

syzbot reported a sleeping function called from invalid context splat in
bucket_table_alloc().

When rhashtable_insert_slow() rehashes the table under rcu_read_lock(), it
calls bucket_table_alloc(..., GFP_ATOMIC | __GFP_NOWARN).  If the bucket
table allocation uses vmalloc, __vmalloc_node_range_noprof() invokes
vm_area_alloc_pages() -> alloc_pages_bulk_mempolicy_noprof() with the
passed GFP_ATOMIC flags.

If the current task has an MPOL_WEIGHTED_INTERLEAVE mempolicy,
alloc_pages_bulk_weighted_interleave() is called and currently hardcodes
GFP_KERNEL when allocating the temporary weights array, triggering a
might_alloc() splat in atomic/RCU contexts.

Pass the gfp flags (masked with GFP_RECLAIM_MASK to strip page-allocator
zone modifiers like __GFP_HIGHMEM) received by
alloc_pages_bulk_weighted_interleave() to kmalloc() instead of hardcoding
GFP_KERNEL.  Since the weights buffer is immediately initialized in full,
kmalloc() is sufficient.

## Which versions are affected by CVE-2026-89986?


## How do I fix CVE-2026-89986?

Apply the vendor's patch.

## Is CVE-2026-89986 being exploited?

There is no known exploitation of CVE-2026-89986 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89986 and fix it if it is affected.

What it is: CVE-2026-89986 is a high-severity denial of service vulnerability in Linux, published on 16 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-2026-89986 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-2026-89986/ (Markdown: https://insights.sbomify.com/CVE-2026-89986/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89986
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89986
- OSV: https://osv.dev/vulnerability/CVE-2026-89986

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89986/
Summaries are generated and may contain mistakes; the official description above is the record.