# CVE-2026-45919: sched/rt: Skip currently executing CPU in rto_next_cpu()

Status: published. Published: 2026-05-27. Updated: 2026-11-06.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < d57d0746276a88ea43a2cc62b849fd8a95e32e41 (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < 3b3c672a66db3de3b40f8a7057864bc1f874ede3 (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < 16ca9f3117e9a294646c897daf08a5ab546c711b (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < 8ad5577b2d4acfd83f03d97a0aece2d18aac5f07 (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < a6a73403733e86748421f2eeaf028c85683ef896 (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < 52aeb1e07ec223caf212f036817976c98d2aa250 (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < 9f25edc5a20cb52a5abbf25f0724bb4732b81801 (affected, git); ≥ 4bdced5c9a2922521e325896a7bbbf0132c94e56; < 94894c9c477e53bcea052e075c53f89df3d2a33e (affected, git); cb1831a83e54cd3269a2420fce81c4fd8ae6f667 (affected, git); 1c37ff78298a6b6063649123356a312e1cce12ca (affected, git); f17c786b28a3060a566a170c2cf3bd7441fc30a3 (affected, git); ≥ 4.4.103; < 4.5 (affected, semver); ≥ 4.9.66; < 4.10 (affected, semver); ≥ 4.14.3; < 4.15 (affected, semver). Source: CNA: Linux
- Linux / Linux: 4.15 (affected); ≥ 0; < 4.15 (unaffected, semver); ≥ 5.10.252; ≤ 5.10.* (unaffected, semver); ≥ 5.15.202; ≤ 5.15.* (unaffected, semver); ≥ 6.1.165; ≤ 6.1.* (unaffected, semver); ≥ 6.6.128; ≤ 6.6.* (unaffected, semver); ≥ 6.12.75; ≤ 6.12.* (unaffected, semver); ≥ 6.18.14; ≤ 6.18.* (unaffected, semver); ≥ 6.19.4; ≤ 6.19.* (unaffected, semver); ≥ 7.0; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.13% as of 2026-11-06; percentile 2.69%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/d57d0746276a88ea43a2cc62b849fd8a95e32e41 (CNA: Linux)

- https://git.kernel.org/stable/c/3b3c672a66db3de3b40f8a7057864bc1f874ede3 (CNA: Linux)

- https://git.kernel.org/stable/c/16ca9f3117e9a294646c897daf08a5ab546c711b (CNA: Linux)

- https://git.kernel.org/stable/c/8ad5577b2d4acfd83f03d97a0aece2d18aac5f07 (CNA: Linux)

- https://git.kernel.org/stable/c/a6a73403733e86748421f2eeaf028c85683ef896 (CNA: Linux)

- https://git.kernel.org/stable/c/52aeb1e07ec223caf212f036817976c98d2aa250 (CNA: Linux)

- https://git.kernel.org/stable/c/9f25edc5a20cb52a5abbf25f0724bb4732b81801 (CNA: Linux)

- https://git.kernel.org/stable/c/94894c9c477e53bcea052e075c53f89df3d2a33e (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-45919; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-45919; retrieved 2026-11-06; source updated Not reported

Revision: 162f2b354bbf0e91b5176d6364473bec1ee77902fbb39df1e732c1eddda50b8b

Canonical: https://y2.dev/cve/CVE-2026-45919

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