Hi, When running cyclictest on latest preempt-rt kernel I met the following the WARNING. It only happens when "taskset -c 0" and "-c 1"(CLOCK_REALTIME) is specified in the command line. After bisecting, it seems this happens since v4.13-rt1. Is this possibly a bug? taskset -c 0 cyclictest -p 80 -i 1000 -l 10000 -c 1 -q [ 164.505613] WARNING: CPU: 0 PID: 864 at /linux-rt-devel/kernel/rcu/tree_plugin.h:309 rcu_note_context_switch+0x56/0x500 [ 164.505614] Modules linked in: [ 164.505617] CPU: 0 PID: 864 Comm: cyclictest Not tainted 4.18.7-rt5-preempt-rt #1 [ 164.505617] Hardware name: Intel Corporation Broadwell Client platform/Basking Ridge, BIOS BDW-E2R1.86C.0118.R01.1503110618 03/11/2015 [ 164.505619] RIP: 0010:rcu_note_context_switch+0x56/0x500 [ 164.505619] Code: 25 c0 4d 01 00 45 84 e4 8b 83 e4 03 00 00 0f 85 04 01 00 00 8b bb e0 03 00 00 85 ff 0f 85 f6 00 00 00 85 c0 0f 8e ee 00 00 00 <0f> 0b 80 bb e8 03 00 00 00 0f 85 f5 [ 164.505641] RSP: 0018:ffffb035c11ffde0 EFLAGS: 00010002 [ 164.505643] RAX: 0000000000000001 RBX: ffff97462c1b0000 RCX: 0000000000000001 [ 164.505643] RDX: 0000000000000000 RSI: ffffffffb019568c RDI: 0000000000000000 [ 164.505644] RBP: ffffb035c11ffe08 R08: ffff97462c1b03d0 R09: 0000000000000000 [ 164.505645] R10: ffff97462c1b03d0 R11: ffff97462c1b03b0 R12: 0000000000000000 [ 164.505646] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 164.505647] FS: 00007fee8978a700(0000) GS:ffff97463b000000(0000) knlGS:0000000000000000 [ 164.505648] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 164.505649] CR2: 00007fee84000010 CR3: 0000000064326001 CR4: 00000000003606f0 [ 164.505649] Call Trace: [ 164.505653] __schedule+0x9a/0x6e0 [ 164.505655] schedule+0x4c/0xf0 [ 164.505657] hrtimer_wait_for_timer+0x67/0xa0 [ 164.505658] ? wait_woken+0x80/0x80 [ 164.505660] timer_wait_for_callback+0x42/0x50 [ 164.505662] __se_sys_timer_delete+0x56/0x130 [ 164.505663] __x64_sys_timer_delete+0x12/0x20 [ 164.505665] do_syscall_64+0x55/0x110 [ 164.505667] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 164.505669] RIP: 0033:0x7fee8996d1d3 [ 164.505669] Code: d7 48 8b 7c 24 08 eb af 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 b8 e2 00 00 00 53 48 89 fb 48 83 ec 08 8b 7f 04 0f 05 <48> 3d 00 f0 ff ff 77 65 89 c5 85 c0 [ 164.505691] RSP: 002b:00007fee89789860 EFLAGS: 00000206 ORIG_RAX: 00000000000000e2 [ 164.505692] RAX: ffffffffffffffda RBX: 00007fee84000b20 RCX: 00007fee8996d1d3 [ 164.505693] RDX: 000000005ba3a7f0 RSI: 00000000000f4240 RDI: 0000000000000000 [ 164.505694] RBP: 000055f8ac9e22b0 R08: 0000000000014f8c R09: 0000000000000001 [ 164.505694] R10: 0000000024d2fa0e R11: 0000000000000206 R12: 00007fee897898f0 [ 164.505695] R13: 0000000000000000 R14: 000055f8ac9e2300 R15: 000055f8ac9e22b0 [ 164.505697] ---[ end trace 0000000000000002 ]--- Zhe
