KCSAN error messages and system hang

Greetings,

I recently experimented with a KCSAN enabled kernel on -CURRENT and got the
following error messages.

CSan: Racy Access [Cpu0 Write Addr=0xfffffe000297f0c8 Size=4 PC=0xffffffff8116a31a<tdq_add>] [Cpu1 Read Addr=0xfffffe000297f0c8 Size=4 PC=0xffffffff8116b3b8<sched_idletd>]

CSan: Racy Access [Cpu0 Read Addr=0xffffffff82314e10 Size=8 PC=0xffffffff8113a66c<binuptime>] [Cpu1 Write Addr=0xffffffff82314e10 Size=8 PC=0xffffffff8113c3a8<tc_windup>]

CSan: Racy Access [Cpu0 Write Addr=0xfffff8003eb646e8 Size=8 PC=0xffffffff811cd358<witness_lock>] [Cpu1 Write Addr=0xfffff8003eb646e8 Size=8 PC=0xffffffff811cd358<witness_lock>]

CSan: Racy Access [Cpu0 Write Addr=0xffffffff831fd0dc Size=1 PC=0xffffffff81169f38<sched_choose>] [Cpu1 Read Addr=0xffffffff831fd0dc Size=1 PC=0xffffffff811672f8<sched_pickcpu>]

CSan: Racy Access [Cpu0 Write Addr=0xffffffff831fd0dc Size=1 PC=0xffffffff81169f38<sched_choose>] [Cpu1 Read Addr=0xffffffff831fd0dc Size=1 PC=0xffffffff8116512c<cpu_search_lowest>]

CSan: Racy Access [Cpu1 Write Addr=0xfffffe0015897400 Size=8 PC=0xffffffff82bf5877<zfs_refcount_remove_many>] [Cpu0 Read Addr=0xfffffe0015897400 Size=8 PC=0xffffffff82bf545c<zfs_refcount_is_zero>]

CSan: Racy Access [Cpu1 Write Addr=0xfffff800fee000b0 Size=4 PC=0xffffffff819574b0<native_lapic_eoi>] [Cpu0 Write Addr=0xfffff800fee000b0 Size=4 PC=0xffffffff819574b0<native_lapic_eoi>]

CSan: Racy Access [Cpu0 Write Addr=0xfffff800fee00320 Size=4 PC=0xffffffff81959f1a<lapic_et_start>] [Cpu1 Write Addr=0xfffff800fee00320 Size=4 PC=0xffffffff81959f1a<lapic_et_start>]

CSan: Racy Access [Cpu1 Write Addr=0xfffff8000bb268c4 Size=4 PC=0xffffffff8168f96b<vm_object_shadow>] [Cpu0 Read Addr=0xfffff8000bb268c4 Size=4 PC=0xffffffff8166f847<vm_fault>]

CSan: Racy Access [Cpu0 Read Addr=0xffffffff831fd0c8 Size=4 PC=0xffffffff81169e81<sched_runnable>] [Cpu1 Write Addr=0xffffffff831fd0c8 Size=4 PC=0xffffffff8116a31a<tdq_add>]

CSan: Racy Access [Cpu1 Write Addr=0xfffff800fee00320 Size=4 PC=0xffffffff81959f1a<lapic_et_start>] [Cpu0 Write Addr=0xfffff800fee00320 Size=4 PC=0xffffffff81959f1a<lapic_et_start>]

CSan: Racy Access [Cpu0 Write Addr=0xffffffff831fd0c8 Size=4 PC=0xffffffff81167b4e<tdq_load_rem>] [Cpu1 Read Addr=0xffffffff831fd0c8 Size=4 PC=0xffffffff811654de<cpu_search_highest>]

These messages appeared during boot. Any hints on debugging this further? 
I am not sure on how to find the corresponding code that leads to this error messages.

Another problem with the KCSAN configuration is that the system reproducibly 
hangs after a few minutes. Any hints how to debug a hang where also much appreciated.

Best regards,

Gordon