Hi Jason, With v4.16-rc1 I see a low of these when running my KVM/ARM test loop: BUG: using smp_processor_id() in preemptible [00000000] code: vhost-2877/2900 caller is debug_smp_processor_id+0x1c/0x28 CPU: 0 PID: 2900 Comm: vhost-2877 Not tainted 4.16.0-rc1 #1333 Hardware name: APM X-Gene Mustang board (DT) Call trace: dump_backtrace+0x0/0x180 show_stack+0x24/0x30 dump_stack+0x8c/0xac check_preemption_disabled+0xf8/0x100 debug_smp_processor_id+0x1c/0x28 xdp_do_flush_map+0x24/0x48 tun_sendmsg+0x90/0xa0 handle_tx+0x254/0x548 handle_tx_kick+0x20/0x30 vhost_worker+0xc0/0x158 kthread+0x104/0x130 ret_from_fork+0x10/0x1c I confirmed that reverting 762c330d670e, "tuntap: add missing xdp flush", 2018-02-07 solves the problem for me. I'm not at all familiar with this part of the kernel and not sure what the proper fix is. I'd be grateful if you could take a look and I'm happy to help test etc. Thanks, -Christoffer
