---
id: CVE-2026-46017
title: 'mm: fix deferred split queue races during migration'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm: fix deferred split queue races during migration

  migrate_folio_move() records the deferred split queue state from src and
  replays it on dst.  Replaying it after rem…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    cbf75cf212ee6e499abc1757fb4b5ae6d70ed0aa
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    3bac01168982ec3e3bf87efdc1807c7933590a85
  - Linux < 7.0.4
  - Linux (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:05:11.945193Z'
published: '2026-05-27'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:13:32.093Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-46017'
references:
  - url: 'https://git.kernel.org/stable/c/cbf75cf212ee6e499abc1757fb4b5ae6d70ed0aa'
  - url: 'https://git.kernel.org/stable/c/3bac01168982ec3e3bf87efdc1807c7933590a85'
tags:
  - cve.org
epss: 0.00105
epssPercentile: 0.01055
ingestedAt: '2026-11-06T16:57:43.350Z'
---

## Overview

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

mm: fix deferred split queue races during migration

migrate_folio_move() records the deferred split queue state from src and
replays it on dst.  Replaying it after remove_migration_ptes(src, dst, 0)
makes dst visible before it is requeued, so a concurrent rmap-removal path
can mark dst partially mapped and trip the WARN in deferred_split_folio().

Move the requeue before remove_migration_ptes() so dst is back on the
deferred split queue before it becomes visible again.

Because migration still holds dst locked at that point, teach
deferred_split_scan() to requeue a folio when folio_trylock() fails. 
Otherwise a fully mapped underused folio can be dequeued by the shrinker
and silently lost from split_queue.

[ziy@nvidia.com: move the comment]

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cbf75cf212ee6e499abc1757fb4b5ae6d70ed0aa`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3bac01168982ec3e3bf87efdc1807c7933590a85`
- `Linux < 7.0.4`
- `Linux (all versions)`

## Remediation

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