Hi Satheesh, > > Currently the kernel detects if its running on a shared lpar platform > > and requests home node associativity before the scheduler sched_domains > > are setup. However between the time NUMA setup is initialized and the > > request for home node associativity, workqueue initializes its per node > > cpumask. The per node workqueue possible cpumask may turn invalid > > after home node associativity resulting in weird situations like > > workqueue possible cpumask being a subset of workqueue online cpumask. > > Env: > HW: Power8 > Host/Guest Kernel: 5.3.0-rc5-00172-g13e3f1076e29 (linux master + this series) > Qemu: 4.0.90 (v4.1.0-rc3) > > Guest Config: > .. > <vcpu placement='static' current='2'>4</vcpu> > ... > <kernel>/home/kvmci/linux/vmlinux</kernel> > <cmdline>root=/dev/sda2 rw console=tty0 console=ttyS0,115200 > init=/sbin/init initcall_debug numa=debug crashkernel=1024M > selinux=0</cmdline> > ... > <topology sockets='1' cores='2' threads='2'/> > <numa> > <cell id='0' cpus='0-1' memory='2097152' unit='KiB'/> > <cell id='1' cpus='2-3' memory='2097152' unit='KiB'/> > </numa> > > Event: > vcpu hotplug > > [root@atest-guest ~]# [ 41.447170] random: crng init done > [ 41.448153] random: 7 urandom warning(s) missed due to ratelimiting > [ 51.727256] VPHN hcall succeeded. Reset polling... > [ 51.826301] adding cpu 2 to node 1 > [ 51.856238] WARNING: workqueue cpumask: online intersect > possible > intersect > [ 51.916297] VPHN hcall succeeded. Reset polling... > [ 52.036272] adding cpu 3 to node 1 >
Thanks for testing. The fix for this patch series was to make sure per node workqueue possible cpus is updated correctly at boot. However Node hotplug on KVM guests and dlpar on PowerVM lpars aren't covered by this patch series. On systems that support shared processor, the associativity of the possible cpus is not known at boot time. Hence we will not be able to update the per node workquque possible cpumask. -- Thanks and Regards Srikar Dronamraju
