Note: dlsymtab is not in standards. but just in case.
(gdb) bt
#0 getpid () at task/task_getpid.c:91
#1 0x00000000004fbc9d in modlib_registry_lock ()
at modlib/modlib_registry.c:89
#2 0x0000000000719ee0 in modsym (handle=0xffffffffffffffff,
name=0x7fa7ebdde8c7 "mmap") at module/mod_modsym.c:92
#3 0x000000000071597d in dlsym (handle=0xffffffffffffffff,
name=0x7fa7ebdde8c7 "mmap") at dlfcn/lib_dlsym.c:164
#4 0x00007fa7ebdbeb39 in ?? () from /lib/x86_64-linux-gnu/libasan.so.5
#5 0x00007fa7ebd79b28 in ?? () from /lib/x86_64-linux-gnu/libasan.so.5
#6 0x00007fa7ebd9d7a7 in ?? () from /lib/x86_64-linux-gnu/libasan.so.5
#7 0x00007fa7ec6ce03a in ?? () from /lib64/ld-linux-x86-64.so.2
#8 0x00007fa7ec6ce141 in ?? () from /lib64/ld-linux-x86-64.so.2
#9 0x00007fa7ec6be13a in ?? () from /lib64/ld-linux-x86-64.so.2
#10 0x0000000000000001 in ?? ()
#11 0x00007fff028f686b in ?? ()
#12 0x0000000000000000 in ?? ()
(gdb) quit
c52854f5bb