Linux Kernel Vulnerability in CPU Scheduling by IBM

CVE-2025-40163

What is CVE-2025-40163?

A vulnerability in the Linux kernel's CPU scheduling system has been identified, affecting the dl_server functionality. During operations to remove a CPU, if the dl_server hrtimer is enqueued shortly before the CPU is taken offline, a kernel warning may occur. This issue was reported through the IBM CI tool when executing the CPU removal command via drmgr. To resolve this issue, it is necessary to ensure that the dl_server is properly stopped before the CPU is marked as offline, preventing the hrtimer from firing and causing unexpected kernel warnings.

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