CVE-2026-89753

Received Received - Intake

RCU Tasks Stall in Linux Kernel Memory Reclaim

Publication date: 2026-09-11

Last updated on: 2026-09-14

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: mm/vmscan: report RCU-tasks quiescent states in shrink_lruvec() I am seeing some rcu_tasks stalls in the Meta fleet during reclaim. INFO: rcu_tasks detected stalls on tasks: 0000000088620d09: .. nvcsw: 6735/6735 holdout: 1 idle_cpu: -1/8 task:GlobalCPUThread state:R running task pid:2552016 tgid:2524552 Call Trace: shrink_lruvec mem_cgroup_iter shrink_node do_try_to_free_pages try_to_free_pages __alloc_frozen_pages_noprof alloc_pages_noprof pte_alloc_one __pte_alloc handle_mm_fault Nothing promises direct reclaim returns in bounded time, and the scan loop in shrink_lruvec() only calls cond_resched(), which is a no-op on PREEMPTION kernels. Involuntary preemption is not a Tasks-RCU quiescent state, so the reclaiming task never reports one and becomes a holdout. Upgrade it to cond_resched_tasks_rcu_qs(), which reports a quiescent state even when cond_resched() does nothing. PS: This has been discussed in [1]

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-11

Last Modified

2026-09-14

Generated

2026-10-02

AI Q&A

2026-09-12

EPSS Evaluated

2026-10-01

NVD

CVE-2026-89753

EUVD

EUVD-2026-76665

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves RCU-tasks stalls during memory reclaim. The issue occurs in the shrink_lruvec() function where tasks fail to report quiescent states to the RCU-tasks subsystem. This happens because cond_resched() does not report a quiescent state on PREEMPTION kernels, causing tasks to become holdouts and stall the system.

Detection Guidance

This vulnerability manifests as RCU-tasks stalls during memory reclaim operations. Monitor kernel logs for messages like 'rcu_tasks detected stalls on tasks' or check for tasks stuck in 'shrink_lruvec' or 'GlobalCPUThread' states. Use 'dmesg | grep -i rcu_tasks' to detect stalls. Check for high latency in memory reclaim with 'vmstat 1' and look for processes in uninterruptible sleep state with 'ps aux | grep D'.

Impact Analysis

This vulnerability can lead to system stalls or delays during memory reclamation processes. It may cause performance degradation or unresponsiveness in systems running affected Linux kernels, particularly those with high memory pressure or frequent reclaim operations.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It involves RCU-tasks stalls in the Linux kernel during memory reclaim operations, which may cause system delays but does not inherently violate data protection or privacy requirements.

Mitigation Strategies

Upgrade the Linux kernel to a version containing the fix for this issue. The patch replaces cond_resched() with cond_resched_tasks_rcu_qs() in shrink_lruvec(). Apply kernel updates from your distribution vendor immediately. If immediate upgrade is not possible, monitor systems closely for RCU-tasks stalls and consider reducing memory pressure by optimizing applications or adding resources.

Hi! I’m here to help you understand CVE-2026-89753. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70