CVE-2026-68421: sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()
In the Linux kernel, the following vulnerability has been resolved:
schedext: Don't warn on core-sched forced idle in putprevtaskscx()
putprevtaskscx() warns when a runnable task drops to a lower schedclass without SCXOPSENQLAST, on the assumption that balanceone() would have kept it running. Core scheduling breaks that: a forced-idle SMT sibling reschedules through the corepick fast path in picknexttask(), which skips picktaskscx() and thus balanceone(), so a runnable task can drop to idle with ENQLAST unset.
Gate the warning on schedcpucookiematch(): a cookie mismatch means core scheduling forced the idle, while a match (or core scheduling off) still catches a genuine missing-ENQLAST drop.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-68421?
The severity of CVE-2026-68421 is rated as risk level 2.
What does CVE-2026-68421 affect?
CVE-2026-68421 affects the Linux kernel's scheduling mechanism.
How do I fix CVE-2026-68421?
To fix CVE-2026-68421, update to the patched version of the Linux kernel that addresses this vulnerability.
What is the nature of CVE-2026-68421?
CVE-2026-68421 addresses an issue with warnings on core-sched forced idle in the function put_prev_task_scx() in the Linux kernel.
When was CVE-2026-68421 published?
CVE-2026-68421 was published on August 10, 2026.