---
id: CVE-2026-90183
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  blk-iolatency: clear delay state when freeing policy data

  io.latency can throttle a group which has no latency target of its own.
  When a sibling misses its target, che…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  blk-iolatency: clear delay state when freeing policy data

  io.latency can throttle a group which has no latency target of its own.
  When a sibling misses its target, che…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= d70675121546c35feaceebf7ed9caed8716640f3 <
    02f1b90ab33ef99c89dd96a385b432ff57abc64d
  - >-
    Linux >= d70675121546c35feaceebf7ed9caed8716640f3 <
    8935bf22c0a0db517a7f72f7097300e05dd852f5
  - Linux 4.19
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:12.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90183'
references:
  - url: 'https://git.kernel.org/stable/c/02f1b90ab33ef99c89dd96a385b432ff57abc64d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8935bf22c0a0db517a7f72f7097300e05dd852f5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.866Z'
epss: 0.00189
epssPercentile: 0.08808
---

## Overview

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

blk-iolatency: clear delay state when freeing policy data

io.latency can throttle a group which has no latency target of its own.
When a sibling misses its target, check_scale_change() scales down its
peers, and a peer that reaches queue depth one gets blkcg_use_delay()
called on it on every further scale-down, even with min_lat_nsec == 0.

iolatency_pd_offline() resets the target through
iolatency_set_min_lat_nsec(), which clears the delay only on a nonzero
to zero transition, so it never clears such a peer.  Freeing the policy
data then leaves blkg->use_delay set and blkcg->congestion_count
elevated with nothing left that can drop it.

blk_cgroup_congested() then returns true for every task in that cgroup
and its descendants for as long as the cgroup lives: page_cache_sync_ra()
cuts readahead to a single page, page_cache_async_ra() skips it
altogether, and __folio_throttle_swaprate() takes swap_avail_lock and
schedules a throttle on anonymous folio allocation.

Clear the delay in iolatency_pd_free().  By then bio-held blkg
references have drained, or the queue is frozen for policy
deactivation, so check_scale_change() cannot re-arm it.  The free
callback can also see policy data which was never attached to a blkg,
hence the pd->blkg check.

## Remediation

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