{"id":"CVE-2026-68421","title":"sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()\n\nput_prev_task_scx() warns when a runnable task drops to a lower sched_class\nwithout SCX_OPS_ENQ_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < 6267ebee9f2f3e26f4968bf6dc29d350620fa320","Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < 2907e9d0f05b506dfd58aec589a23042a56ef36b","Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < e2f188cdbf8312289532c36eb4e9eb1c9544d43a","Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da","Linux 6.12"],"published":"2026-08-10","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:44:06.128Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68421","references":[{"url":"https://git.kernel.org/stable/c/6267ebee9f2f3e26f4968bf6dc29d350620fa320"},{"url":"https://git.kernel.org/stable/c/2907e9d0f05b506dfd58aec589a23042a56ef36b"},{"url":"https://git.kernel.org/stable/c/e2f188cdbf8312289532c36eb4e9eb1c9544d43a"},{"url":"https://git.kernel.org/stable/c/b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da"}],"tags":["cve.org"],"epss":0.00192,"epssPercentile":0.08372,"ingestedAt":"2026-10-21T12:48:53.598Z","slug":"CVE-2026-68421","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()\n\nput_prev_task_scx() warns when a runnable task drops to a lower sched_class\nwithout SCX_OPS_ENQ_LAST, on the assumption that balance_one() would have\nkept it running. Core scheduling breaks that: a forced-idle SMT sibling\nreschedules through the core_pick fast path in pick_next_task(), which skips\npick_task_scx() and thus balance_one(), so a runnable task can drop to idle\nwith ENQ_LAST unset.\n\nGate the warning on sched_cpu_cookie_match(): a cookie mismatch means core\nscheduling forced the idle, while a match (or core scheduling off) still\ncatches a genuine missing-ENQ_LAST drop.\n\n## Affected\n\n- `Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < 6267ebee9f2f3e26f4968bf6dc29d350620fa320`\n- `Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < 2907e9d0f05b506dfd58aec589a23042a56ef36b`\n- `Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < e2f188cdbf8312289532c36eb4e9eb1c9544d43a`\n- `Linux >= 7c65ae81ea86a6ed8086e1a5651acd766187f19b < b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da`\n- `Linux 6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}