---
id: CVE-2026-98079
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  btrfs: zstd: fix lost wakeup when waiting for a workspace

  A writer can sleep forever in zstd_get_workspace() even though a workspace
  is free
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  btrfs: zstd: fix lost wakeup when waiting for a workspace

  A writer can sleep forever in zstd_get_workspace() even though a workspace
  is free.  When zstd_alloc_workspac…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 <
    d8f57049521948df5f50797141472fbbed3b0723
  - >-
    Linux >= 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 <
    0de9f31d447ae71ab08c7850a321682f8d2907c3
  - >-
    Linux >= 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 <
    2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7
  - Linux 5.1
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:37.307'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98079'
references:
  - url: 'https://git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.836Z'
---

## Overview

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

btrfs: zstd: fix lost wakeup when waiting for a workspace

A writer can sleep forever in zstd_get_workspace() even though a workspace
is free.  When zstd_alloc_workspace() fails, the task is queued on
zwsm->wait and schedules unconditionally, never re-testing the pool.
zstd_put_workspace() publishes the workspace and then calls cond_wake_up(),
which only wakes when a sleeper is already visible, so a workspace returned
between the failed allocation and prepare_to_wait() wakes nobody.  The
window is wide: zstd_alloc_workspace() goes through kvmalloc() and may
enter reclaim.

Only a max level workspace triggers the wakeup and one is deliberately kept
allocated as the fallback every waiter waits for, so once its wakeup is
lost the writer stays in TASK_UNINTERRUPTIBLE until some other task happens
to return one.  Re-check the pool after prepare_to_wait() has published the
waiter, and use the workspace if one turned up.

## Remediation

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