ThreadSanitizer: lock-order-inversion (potential deadlock) in zone_refreshkeys

WARNING: ThreadSanitizer: lock-order-inversion (potential deadlock)
  Cycle in lock order graph: M1 (0x000000000001) => M2 (0x000000000000) => M1

  Mutex M2 acquired here while holding mutex M1 in thread T1:
    #0 pthread_mutex_lock <null>
    #1 dns_view_findzonecut lib/dns/view.c:1326:2
    #2 fctx_create lib/dns/resolver.c:5144:13
    #3 dns_resolver_createfetch lib/dns/resolver.c:10977:12
    #4 zone_refreshkeys lib/dns/zone.c:10830:13
    #5 zone_maintenance lib/dns/zone.c:11065:5
    #6 zone_timer lib/dns/zone.c:14652:2
    #7 task_run lib/isc/task.c:857:5
    #8 isc_task_run lib/isc/task.c:944:10
    #9 isc__nm_async_task lib/isc/netmgr/netmgr.c:730:24
    #10 process_netievent lib/isc/netmgr/netmgr.c
    #11 process_queue lib/isc/netmgr/netmgr.c:885:8
    #12 process_tasks_queue lib/isc/netmgr/netmgr.c:756:10
    #13 process_queues lib/isc/netmgr/netmgr.c:772:7
    #14 async_cb lib/isc/netmgr/netmgr.c:671:2
    #15 uv__async_io /home/ondrej/Projects/tsan/libuv/src/unix/async.c:163:5
    #16 uv__io_poll /home/ondrej/Projects/tsan/libuv/src/unix/linux-core.c:462:11
    #17 uv_run /home/ondrej/Projects/tsan/libuv/src/unix/core.c:392:5
    #18 nm_thread lib/isc/netmgr/netmgr.c:597:11
    #19 isc__trampoline_run lib/isc/trampoline.c:184:11

  Mutex M1 previously acquired by the same thread here:
    #0 pthread_mutex_lock <null>
    #1 zone_refreshkeys lib/dns/zone.c:10717:2
    #2 zone_maintenance lib/dns/zone.c:11065:5
    #3 zone_timer lib/dns/zone.c:14652:2
    #4 task_run lib/isc/task.c:857:5
    #5 isc_task_run lib/isc/task.c:944:10
    #6 isc__nm_async_task lib/isc/netmgr/netmgr.c:730:24
    #7 process_netievent lib/isc/netmgr/netmgr.c
    #8 process_queue lib/isc/netmgr/netmgr.c:885:8
    #9 process_tasks_queue lib/isc/netmgr/netmgr.c:756:10
    #10 process_queues lib/isc/netmgr/netmgr.c:772:7
    #11 async_cb lib/isc/netmgr/netmgr.c:671:2
    #12 uv__async_io /home/ondrej/Projects/tsan/libuv/src/unix/async.c:163:5
    #13 uv__io_poll /home/ondrej/Projects/tsan/libuv/src/unix/linux-core.c:462:11
    #14 uv_run /home/ondrej/Projects/tsan/libuv/src/unix/core.c:392:5
    #15 nm_thread lib/isc/netmgr/netmgr.c:597:11
    #16 isc__trampoline_run lib/isc/trampoline.c:184:11

  Mutex M1 acquired here while holding mutex M2 in thread T2:
    #0 pthread_mutex_lock <null>
    #1 dns_zone_flush lib/dns/zone.c:11443:2
    #2 view_flushanddetach lib/dns/view.c:657:5
    #3 dns_view_flushanddetach lib/dns/view.c:690:2
    #4 shutdown_server bin/named/server.c:10056:4
    #5 task_run lib/isc/task.c:857:5
    #6 isc_task_run lib/isc/task.c:944:10
    #7 isc__nm_async_task lib/isc/netmgr/netmgr.c:730:24
    #8 process_netievent lib/isc/netmgr/netmgr.c
    #9 process_queue lib/isc/netmgr/netmgr.c:885:8
    #10 process_tasks_queue lib/isc/netmgr/netmgr.c:756:10
    #11 process_queues lib/isc/netmgr/netmgr.c:772:7
    #12 async_cb lib/isc/netmgr/netmgr.c:671:2
    #13 uv__async_io /home/ondrej/Projects/tsan/libuv/src/unix/async.c:163:5
    #14 uv__io_poll /home/ondrej/Projects/tsan/libuv/src/unix/linux-core.c:462:11
    #15 uv_run /home/ondrej/Projects/tsan/libuv/src/unix/core.c:392:5
    #16 nm_thread lib/isc/netmgr/netmgr.c:597:11
    #17 isc__trampoline_run lib/isc/trampoline.c:184:11

  Mutex M2 previously acquired by the same thread here:
    #0 pthread_mutex_lock <null>
    #1 view_flushanddetach lib/dns/view.c:645:3
    #2 dns_view_flushanddetach lib/dns/view.c:690:2
    #3 shutdown_server bin/named/server.c:10056:4
    #4 task_run lib/isc/task.c:857:5
    #5 isc_task_run lib/isc/task.c:944:10
    #6 isc__nm_async_task lib/isc/netmgr/netmgr.c:730:24
    #7 process_netievent lib/isc/netmgr/netmgr.c
    #8 process_queue lib/isc/netmgr/netmgr.c:885:8
    #9 process_tasks_queue lib/isc/netmgr/netmgr.c:756:10
    #10 process_queues lib/isc/netmgr/netmgr.c:772:7
    #11 async_cb lib/isc/netmgr/netmgr.c:671:2
    #12 uv__async_io /home/ondrej/Projects/tsan/libuv/src/unix/async.c:163:5
    #13 uv__io_poll /home/ondrej/Projects/tsan/libuv/src/unix/linux-core.c:462:11
    #14 uv_run /home/ondrej/Projects/tsan/libuv/src/unix/core.c:392:5
    #15 nm_thread lib/isc/netmgr/netmgr.c:597:11
    #16 isc__trampoline_run lib/isc/trampoline.c:184:11

  Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create lib/isc/pthreads/thread.c:79:8
    #2 isc_nm_start lib/isc/netmgr/netmgr.c:303:3
    #3 create_managers bin/named/main.c:957:15
    #4 setup bin/named/main.c:1267:11
    #5 main bin/named/main.c:1558:2

  Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create lib/isc/pthreads/thread.c:79:8
    #2 isc_nm_start lib/isc/netmgr/netmgr.c:303:3
    #3 create_managers bin/named/main.c:957:15
    #4 setup bin/named/main.c:1267:11
    #5 main bin/named/main.c:1558:2

SUMMARY: ThreadSanitizer: lock-order-inversion (potential deadlock) in __interceptor_pthread_mutex_lock