Description of problem: A customer (AltioStar, this is related to bz1886312) asked for clarifications about lru-add-drain kthread. They were worried that it might cause latency spikes on isolated cpus, as its affinity cannot be restricted to non-isolated cpus. Investigation showed that, on RT kernel, this kthread is allocated (by the workqueue subsystem), but never actually used since RT kernel doesn't use workqueues to perform remote_lru_add_drain. Even though there is practically no harm in creating such kthread, it would be good to remove it as it creates confusion (at least). Version-Release number of selected component (if applicable): kernel-rt-3.10.0-1160.7.1.rt56.1140.el7
Fix posted http://post-office.corp.redhat.com/archives/kernel-rt-team/2020-November/msg00005.html
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Important: kernel-rt security and bug fix update), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2021:2316