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*** Bug 1897329 has been marked as a duplicate of this bug. ***
Comment 4David Hildenbrand
2020-11-16 09:04:08 UTC
Memory hotunplug can severely affect the performance of a running system.
drain_pages() will have to schedule work on all CPUs, to make sure the PCP is fully drained on that CPU. Soon, it will disable the PCP completely while offlining.
Are we sure we want to even allow that for RT kernels? Are there known users?