[Bug 2165732] Re: [UBUNTU 24.04] kernel: CPU hotplug unsupported by CPUMF

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2165732 Title: [UBUNTU 24.04] kernel: CPU hotplug unsupported by CPUMF Status in Ubuntu on IBM z Systems: New Status in linux package in Ubuntu: New Status in linux source package in Noble: New Bug description: Description: kernel: CPU hotplug unsupported by CPUMF Symptom: The kernel crashes with a panic when CPU hotplug add is triggered during execution of command 'perf stat -- <command>' on LPAR. z/VM is not affected. Problem: CPU hotplug add does not allocate memory and does not initialise per-CPU variables required by the PMU device driver. Reproduction: Run the following commands # echo 0 > /sys/devices/system/cpu/cpu1/online # perf stat -e cycles -i -- stress-ng -t10s --matrix X # sleep 1 # echo 1 > /sys/devices/system/cpu/cpu1/online Solution: Install CPU hotplug handler function to support CPU hotplug add and delete operations. Upstream-ID: ddd52d6c635a2dc628a238c637d928425b0e3f53 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/2165732/+subscriptions