---
id: CVE-2026-98225
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem

  With cgroup.memory=nokmem, shrinker_memcg_alloc() bails out early and
  never allocates an id, so shr…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem

  With cgroup.memory=nokmem, shrinker_memcg_alloc() bails out early and
  never allocates an id, so shr…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= fafaeceb89a5e2e856ff04c2cacb6cae4a2ecb67 <
    469c12a69ab1842a9090b6c074ffedbfd9584f9c
  - >-
    Linux >= fafaeceb89a5e2e856ff04c2cacb6cae4a2ecb67 <
    932cfb25e7ce98d1f93895671ec186a3087e4f80
  - Linux 7.2
published: '2026-10-06'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T09:18:09.587'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98225'
references:
  - url: 'https://git.kernel.org/stable/c/469c12a69ab1842a9090b6c074ffedbfd9584f9c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/932cfb25e7ce98d1f93895671ec186a3087e4f80'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-06T08:50:17.438Z'
---

## Overview

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

mm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem

With cgroup.memory=nokmem, shrinker_memcg_alloc() bails out early and
never allocates an id, so shrinker->id keeps the 0 it got from the
kzalloc() in shrinker_alloc().  __list_lru_init() then copies that 0 into
lru->shrinker_id, where it looks like a valid bit index.

Nothing calls expand_shrinker_info() on nokmem either, so shrinker_nr_max
stays 0 and every memcg ends up with an empty map (map_nr_max == 0).

deferred_split_folio() hands a real memcg to __list_lru_add() regardless
of whether the lru is memcg aware, so the first THP queued in a cgroup
does set_shrinker_bit(memcg, nid, 0) and trips the bounds check:

WARNING: mm/shrinker.c:212 at set_shrinker_bit+0x7d/0x90, CPU#126
Call Trace:
 <TASK>
 deferred_split_folio+0x18c/0x220
 map_anon_folio_pmd_nopf+0xdd/0x130
 map_anon_folio_pmd_pf+0x14/0xb0
 do_huge_pmd_anonymous_page+0x1a1/0x620
 __handle_mm_fault+0xea9/0x10d0
 handle_mm_fault+0xe5/0x320
 do_user_addr_fault+0x1cc/0x870
 exc_page_fault+0x81/0x1b0
 asm_exc_page_fault+0x27/0x30
 </TASK>

Harmless, the WARN_ON_ONCE() is what keeps the out of bounds unit[] read
from happening, but the id should not look valid in the first place. 
Clear it before returning.

Two other spots could paper over this: drop the id in __list_lru_init()
when nokmem turns memcg_aware off, or make deferred_split_folio() pass
NULL like list_lru_add_obj() does.  Both leave shrinker->id lying around
for the next caller, so fix it where the id is handed out.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.