sched/deadline: Stop dl_server before CPU goes offline

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Summary

CVECVE-2025-40163
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-11-12 11:15:46 UTC
Updated2026-06-01 17:16:36 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: sched/deadline: Stop dl_server before CPU goes offline IBM CI tool reported kernel warning[1] when running a CPU removal operation through drmgr[2]. i.e "drmgr -c cpu -r -q 1" WARNING: CPU: 0 PID: 0 at kernel/sched/cpudeadline.c:219 cpudl_set+0x58/0x170 NIP [c0000000002b6ed8] cpudl_set+0x58/0x170 LR [c0000000002b7cb8] dl_server_timer+0x168/0x2a0 Call Trace: [c000000002c2f8c0] init_stack+0x78c0/0x8000 (unreliable) [c0000000002b7cb8] dl_server_timer+0x168/0x2a0 [c00000000034df84] __hrtimer_run_queues+0x1a4/0x390 [c00000000034f624] hrtimer_interrupt+0x124/0x300 [c00000000002a230] timer_interrupt+0x140/0x320 Git bisects to: commit 4ae8d9aa9f9d ("sched/deadline: Fix dl_server getting stuck") This happens since: - dl_server hrtimer gets enqueued close to cpu offline, when kthread_park enqueues a fair task. - CPU goes offline and drmgr removes it from cpu_present_mask. - hrtimer fires and warning is hit. Fix it by stopping the dl_server before CPU is marked dead. [1]: https://lore.kernel.org/all/[email protected]/ [2]: https://github.com/ibm-power-utilities/powerpc-utils/tree/next/src/drmgr [sshegde: wrote the changelog and tested it]

Risk And Classification

EPSS: 0.000240000 probability, percentile 0.070050000 (date 2026-06-04)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 030167dcadf50a9f9dac4de6fa4c34f4f7afeed7 d7fd56ed5e07e053a5eea6112d61fcaded653b87 git Not specified
CNA Linux Linux affected 4ae8d9aa9f9dc7137ea5e564d79c5aa5af1bc45c ab6c0f158508bb16d483add70b73a73f95651c33 git Not specified
CNA Linux Linux affected 4ae8d9aa9f9dc7137ea5e564d79c5aa5af1bc45c ee6e44dfe6e50b4a5df853d933a96bdff5309e6e git Not specified
CNA Linux Linux affected 6.17 Not specified
CNA Linux Linux unaffected 6.17 semver Not specified
CNA Linux Linux unaffected 6.17.5 6.17.* semver Not specified
CNA Linux Linux unaffected 6.18 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/ab6c0f158508bb16d483add70b73a73f95651c33 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d7fd56ed5e07e053a5eea6112d61fcaded653b87 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ee6e44dfe6e50b4a5df853d933a96bdff5309e6e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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