---
id: CVE-2026-45919
title: 'sched/rt: Skip currently executing CPU in rto_next_cpu()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sched/rt: Skip currently executing CPU in rto_next_cpu()

  CPU0 becomes overloaded when hosting a CPU-bound RT task, a non-CPU-bound
  RT task, and a CFS task stuck in ker…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    d57d0746276a88ea43a2cc62b849fd8a95e32e41
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    3b3c672a66db3de3b40f8a7057864bc1f874ede3
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    16ca9f3117e9a294646c897daf08a5ab546c711b
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    8ad5577b2d4acfd83f03d97a0aece2d18aac5f07
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    a6a73403733e86748421f2eeaf028c85683ef896
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    52aeb1e07ec223caf212f036817976c98d2aa250
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    9f25edc5a20cb52a5abbf25f0724bb4732b81801
  - >-
    Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 <
    94894c9c477e53bcea052e075c53f89df3d2a33e
  - Linux cb1831a83e54cd3269a2420fce81c4fd8ae6f667
  - Linux 1c37ff78298a6b6063649123356a312e1cce12ca
  - Linux f17c786b28a3060a566a170c2cf3bd7441fc30a3
  - Linux >= 4.4.103 < 4.5
  - Linux >= 4.9.66 < 4.10
  - Linux >= 4.14.3 < 4.15
  - Linux 4.15
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T15:44:31.654477Z'
published: '2026-05-27'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T15:53:12.903Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-45919'
references:
  - url: 'https://git.kernel.org/stable/c/d57d0746276a88ea43a2cc62b849fd8a95e32e41'
  - url: 'https://git.kernel.org/stable/c/3b3c672a66db3de3b40f8a7057864bc1f874ede3'
  - url: 'https://git.kernel.org/stable/c/16ca9f3117e9a294646c897daf08a5ab546c711b'
  - url: 'https://git.kernel.org/stable/c/8ad5577b2d4acfd83f03d97a0aece2d18aac5f07'
  - url: 'https://git.kernel.org/stable/c/a6a73403733e86748421f2eeaf028c85683ef896'
  - url: 'https://git.kernel.org/stable/c/52aeb1e07ec223caf212f036817976c98d2aa250'
  - url: 'https://git.kernel.org/stable/c/9f25edc5a20cb52a5abbf25f0724bb4732b81801'
  - url: 'https://git.kernel.org/stable/c/94894c9c477e53bcea052e075c53f89df3d2a33e'
tags:
  - cve.org
epss: 0.0013
epssPercentile: 0.02691
ingestedAt: '2026-11-06T16:57:43.386Z'
---

## Overview

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

sched/rt: Skip currently executing CPU in rto_next_cpu()

CPU0 becomes overloaded when hosting a CPU-bound RT task, a non-CPU-bound
RT task, and a CFS task stuck in kernel space. When other CPUs switch from
RT to non-RT tasks, RT load balancing (LB) is triggered; with
HAVE_RT_PUSH_IPI enabled, they send IPIs to CPU0 to drive the execution
of rto_push_irq_work_func. During push_rt_task on CPU0,
if next_task->prio < rq->donor->prio, resched_curr() sets NEED_RESCHED
and after the push operation completes, CPU0 calls rto_next_cpu().
Since only CPU0 is overloaded in this scenario, rto_next_cpu() should
ideally return -1 (no further IPI needed).

However, multiple CPUs invoking tell_cpu_to_push() during LB increments
rd->rto_loop_next. Even when rd->rto_cpu is set to -1, the mismatch between
rd->rto_loop and rd->rto_loop_next forces rto_next_cpu() to restart its
search from -1. With CPU0 remaining overloaded (satisfying rt_nr_migratory
&& rt_nr_total > 1), it gets reselected, causing CPU0 to queue irq_work to
itself and send self-IPIs repeatedly. As long as CPU0 stays overloaded and
other CPUs run pull_rt_tasks(), it falls into an infinite self-IPI loop,
which triggers a CPU hardlockup due to continuous self-interrupts.

The trigging scenario is as follows:

         cpu0                      cpu1                    cpu2
                                pull_rt_task
                              tell_cpu_to_push
                 <------------irq_work_queue_on
rto_push_irq_work_func
       push_rt_task
    resched_curr(rq)                                   pull_rt_task
    rto_next_cpu                                     tell_cpu_to_push
                      <-------------------------- atomic_inc(rto_loop_next)
rd->rto_loop != next
     rto_next_cpu
   irq_work_queue_on
rto_push_irq_work_func

Fix redundant self-IPI by filtering the initiating CPU in rto_next_cpu().
This solution has been verified to effectively eliminate spurious self-IPIs
and prevent CPU hardlockup scenarios.

## Affected

- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < d57d0746276a88ea43a2cc62b849fd8a95e32e41`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 3b3c672a66db3de3b40f8a7057864bc1f874ede3`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 16ca9f3117e9a294646c897daf08a5ab546c711b`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 8ad5577b2d4acfd83f03d97a0aece2d18aac5f07`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < a6a73403733e86748421f2eeaf028c85683ef896`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 52aeb1e07ec223caf212f036817976c98d2aa250`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 9f25edc5a20cb52a5abbf25f0724bb4732b81801`
- `Linux >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 94894c9c477e53bcea052e075c53f89df3d2a33e`
- `Linux cb1831a83e54cd3269a2420fce81c4fd8ae6f667`
- `Linux 1c37ff78298a6b6063649123356a312e1cce12ca`
- `Linux f17c786b28a3060a566a170c2cf3bd7441fc30a3`
- `Linux >= 4.4.103 < 4.5`
- `Linux >= 4.9.66 < 4.10`
- `Linux >= 4.14.3 < 4.15`
- `Linux 4.15`

## Remediation

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