Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffcd08b700 (LWP 8536)]
[New Thread 0x7fffccf8a700 (LWP 8537)]
[New Thread 0x7fffcce89700 (LWP 8538)]
[New Thread 0x7fffccd88700 (LWP 8539)]
*** Error in `/usr/sbin/knotd': double free or corruption (out): 0x00007fffc8042fe0 ***

Thread 2 "knotd" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffcd08b700 (LWP 8536)]
malloc_consolidate (av=av@entry=0x7fffc8000020) at malloc.c:4202
4202	malloc.c: No such file or directory.
(gdb) bt
#0  malloc_consolidate (av=av@entry=0x7fffc8000020) at malloc.c:4202
#1  0x00007ffff6dcdcea in _int_malloc (av=av@entry=0x7fffc8000020, bytes=bytes@entry=1182) at malloc.c:3485
#2  0x00007ffff6dd07e6 in __libc_calloc (n=<optimized out>, elem_size=<optimized out>) at malloc.c:3271
#3  0x00007ffff7de5076 in _dl_new_object (realname=realname@entry=0x7fffc80459e0 "\220\236", libname=libname@entry=0x7ffff6eb6226 "libgcc_s.so.1",
    type=type@entry=2, loader=loader@entry=0x0, mode=mode@entry=-1879048191, nsid=nsid@entry=0) at dl-object.c:75
#4  0x00007ffff7ddf61d in _dl_map_object_from_fd (name=name@entry=0x7ffff6eb6226 "libgcc_s.so.1", origname=origname@entry=0x0, fd=21, fbp=0x7fffcd089720,
    realname=0x7fffc80459e0 "\220\236", loader=loader@entry=0x0, l_type=2, mode=-1879048191, stack_endp=0x7fffcd089718, nsid=0) at dl-load.c:1006
#5  0x00007ffff7de25ac in _dl_map_object (loader=0x0, loader@entry=0x7ffff7fee4e8, name=name@entry=0x7ffff6eb6226 "libgcc_s.so.1", type=type@entry=2,
    trace_mode=trace_mode@entry=0, mode=mode@entry=-1879048191, nsid=<optimized out>) at dl-load.c:2476
#6  0x00007ffff7ded924 in dl_open_worker (a=a@entry=0x7fffcd089cd0) at dl-open.c:237
#7  0x00007ffff7de9484 in _dl_catch_error (objname=objname@entry=0x7fffcd089cc0, errstring=errstring@entry=0x7fffcd089cc8,
    mallocedp=mallocedp@entry=0x7fffcd089cbf, operate=operate@entry=0x7ffff7ded880 <dl_open_worker>, args=args@entry=0x7fffcd089cd0) at dl-error.c:187
#8  0x00007ffff7ded419 in _dl_open (file=0x7ffff6eb6226 "libgcc_s.so.1", mode=-2147483647, caller_dlopen=0x7ffff6e4aa95 <init+21>, nsid=-2,
    argc=<optimized out>, argv=<optimized out>, env=0x7fffffffec68) at dl-open.c:660
#9  0x00007ffff6e73fed in do_dlopen (ptr=ptr@entry=0x7fffcd089f10) at dl-libc.c:87
#10 0x00007ffff7de9484 in _dl_catch_error (objname=0x7fffcd089ef0, errstring=0x7fffcd089ef8, mallocedp=0x7fffcd089eef, operate=0x7ffff6e73fb0 <do_dlopen>,
    args=0x7fffcd089f10) at dl-error.c:187
#11 0x00007ffff6e7407f in dlerror_run (operate=operate@entry=0x7ffff6e73fb0 <do_dlopen>, args=args@entry=0x7fffcd089f10) at dl-libc.c:46
#12 0x00007ffff6e740f2 in __GI___libc_dlopen_mode (name=name@entry=0x7ffff6eb6226 "libgcc_s.so.1", mode=mode@entry=-2147483647) at dl-libc.c:163
#13 0x00007ffff6e4aa95 in init () at ../sysdeps/x86_64/backtrace.c:52
#14 0x00007ffff7101779 in __pthread_once_slow (once_control=0x7ffff70f1110 <once>, init_routine=0x7ffff6e4aa80 <init>) at pthread_once.c:116
#15 0x00007ffff6e4abb4 in __GI___backtrace (array=array@entry=0x7fffcd089fd0, size=size@entry=64) at ../sysdeps/x86_64/backtrace.c:105
#16 0x00007ffff6d749c6 in backtrace_and_maps (do_abort=<optimized out>, do_abort@entry=2, written=<optimized out>, fd=fd@entry=20)
    at ../sysdeps/unix/sysv/linux/libc_fatal.c:47
#17 0x00007ffff6dc5bcb in __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7ffff6ebac70 "*** Error in `%s': %s: 0x%s ***\n")
    at ../sysdeps/posix/libc_fatal.c:172
#18 0x00007ffff6dcbfa6 in malloc_printerr (action=3, str=0x7ffff6ebad38 "double free or corruption (out)", ptr=<optimized out>, ar_ptr=<optimized out>)
    at malloc.c:5046
#19 0x00007ffff6dcc79e in _int_free (av=0x7ffff70edb00 <main_arena>, p=0x7fffc8042fd0, have_lock=0) at malloc.c:3902
#20 0x00007ffff7998c05 in knot_rdataset_clear () from /usr/lib/x86_64-linux-gnu/libknot.so.4
#21 0x000055555556e83b in rr_data_clear (mm=0x0, data=0x7fffc8006840) at knot/zone/node.c:35
#22 node_free_rrsets (node=0x7fffc8006930, mm=mm@entry=0x0) at knot/zone/node.c:118
#23 0x0000555555584016 in destroy_node_rrsets_from_tree (node=0x7fffc8006bb0, data=<optimized out>) at knot/zone/contents.c:89
#24 0x00007ffff79a57f1 in ?? () from /usr/lib/x86_64-linux-gnu/libknot.so.4
---Type <return> to continue, or q <return> to quit---
#25 0x00007ffff79a577a in ?? () from /usr/lib/x86_64-linux-gnu/libknot.so.4
#26 0x0000555555585838 in zone_contents_deep_free (contents=contents@entry=0x7fffcd08aa48) at knot/zone/contents.c:1138
#27 0x0000555555578488 in event_load (conf=0x7fffc80008c0, zone=0x5555557e3ba0) at knot/events/handlers/load.c:129
#28 0x0000555555577aaa in event_wrap (task=<optimized out>) at knot/events/events.c:187
#29 0x000055555556e394 in worker_main (thread=thread@entry=0x5555557dc970) at knot/worker/pool.c:78
#30 0x000055555556ad2d in thread_ep (data=0x5555557dc970) at knot/server/dthreads.c:161
#31 0x00007ffff70fa464 in start_thread (arg=0x7fffcd08b700) at pthread_create.c:333
#32 0x00007ffff6e3d9df in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105