Incorrect Synchronization Affecting kernel-zfcpdump-modules-extra package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.19% (10th percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELZFCPDUMPMODULESEXTRA-19830634
  • published16 Sept 2026
  • disclosed11 Sept 2026

Introduced: 11 Sep 2026

NewCVE-2026-89756  (opens in a new tab)
CWE-821  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-zfcpdump-modules-extra.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-zfcpdump-modules-extra package and not the kernel-zfcpdump-modules-extra package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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

mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()

migrate_pages_batch() unmaps each folio before moving it, and every unmap runs the mmu_notifier invalidate callbacks. On KVM hosts try_to_migrate() ends up in kvm_mmu_notifier_invalidate_range_start() -> tdp_mmu_zap_leafs(), which is expensive, so unmapping a large batch keeps the CPU busy for a long time.

The loop already calls cond_resched(), but on PREEMPTION kernels that is a no-op, and involuntary preemption is not a Tasks-RCU quiescent state.

A long batch therefore never reports a quiescent state, and the migrating task (e.g. kcompactd) becomes a Tasks-RCU holdout, stalling the Tasks-RCU grace period for minutes, which is common at Meta fleet:

INFO: rcu_tasks detected stalls on tasks: 0000000055349ecc: .. nvcsw: 1157401/1157401 holdout: 1 idle_cpu: -1/56 task:kcompactd0 state:R running task Call Trace: tdp_mmu_zap_leafs tdp_mmu_next_root gfn_to_pfn_cache_invalidate_start kvm_mmu_notifier_invalidate_range_start __mmu_notifier_invalidate_range_start try_to_migrate_one try_to_migrate migrate_pages_batch migrate_pages compact_zone compact_node kcompactd kthread

Use cond_resched_tasks_rcu_qs() so a quiescent state is reported even when cond_resched() does nothing.

This has also been discussed at [1]

CVSS Base Scores

version 3.1