Suspicious valgrind output

gistfile1.txt

dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6 -v
This is Rakudo version 2019.03.1-112-gc26ca6b built on MoarVM version 2019.03-44-g079d670
implementing Perl 6.d.
dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6-valgrind-m t/04-nativecall/12-sizeof.t
================================================================================================
This is Rakudo Perl 6 running in valgrind, a tool for debugging and profiling programs.
Running a program in valgrind usually takes *a lot* more time than running it directly,
so please be patient.
Valgrind options can be added with MVM_VALGRIND_OPTS environment variable.

This Rakudo version is 2019.03.1.112.gc.26.ca.6.b built on MoarVM version 2019.03.44.g.079.d.670,
running on linuxmint (18.3.Sylvia) / linux (42.16.04.1.Ubuntu.SMP.Tue.Oct.10.16.32.20.UTC.2017)
------------------------------------------------------------------------------------------------
==18212== Memcheck, a memory error detector
==18212== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==18212== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==18212== Command: /home/dogbert/repos/rakudo/nqp/MoarVM/../../install/bin/moar --execname=./perl6-valgrind-m --libpath=/home/dogbert/repos/rakudo/install/share/nqp/lib --libpath=. --libpath=blib ./perl6.moarvm --nqp-lib=blib t/04-nativecall/12-sizeof.t
==18212== 
1..17
==18212== Thread 5:
==18212== Syscall param epoll_pwait(sigmask) points to unaddressable byte(s)
==18212==    at 0x590D627: epoll_pwait (epoll_pwait.c:42)
==18212==    by 0x515AC6E: uv__io_poll (linux-core.c:279)
==18212==    by 0x5160EDF: uv_run (core.c:361)
==18212==    by 0x503A210: thread_initial_invoke (threads.c:59)
==18212==    by 0x50141BD: MVM_interp_run (interp.c:128)
==18212==    by 0x503A295: start_thread (threads.c:87)
==18212==    by 0x5EE06B9: start_thread (pthread_create.c:333)
==18212==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==18212== 
ok 1 - sizeof(Foo)
ok 2 - sizeof(Bar)
ok 3 - sizeof(Baz)
ok 4 - sizeof(Buz)
ok 5 - sizeof(int)
ok 6 - sizeof(long)
ok 7 - sizeof(Pointer)
ok 8 - sizeof(bool)
ok 9 - sizeof(size_t)
ok 10 - sizeof(foo1)
ok 11 - sizeof(foo2)
ok 12 - sizeof(foo3)
ok 13 - sizeof(foo4)
ok 14 - sizeof(foo5)
ok 15 - sizeof(foo6)
ok 16 - sizeof(foo7)
ok 17 - sizeof(foo8)
==18212== 
==18212== HEAP SUMMARY:
==18212==     in use at exit: 80,089,056 bytes in 272,938 blocks
==18212==   total heap usage: 717,651 allocs, 444,713 frees, 392,320,891 bytes allocated
==18212== 
==18212== LEAK SUMMARY:
==18212==    definitely lost: 875,664 bytes in 8,465 blocks
==18212==    indirectly lost: 17,316 bytes in 724 blocks
==18212==      possibly lost: 249,520 bytes in 4,439 blocks
==18212==    still reachable: 78,946,556 bytes in 259,310 blocks
==18212==         suppressed: 0 bytes in 0 blocks
==18212== Rerun with --leak-check=full to see details of leaked memory
==18212== 
==18212== For counts of detected and suppressed errors, rerun with: -v
==18212== ERROR SUMMARY: 6 errors from 1 contexts (suppressed: 0 from 0)