CVE-2026-89753

/// Technical 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

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References