Valgrind VVoes

[kondziu]

When running UFOs with valgrind, initialization fails with a confusing error (I'm new to valgrind, I hope this makes sense):

/opt/R-3.6.0/bin/R -d "valgrind --track-origins=yes --keep-stacktraces=alloc-and-free --error-limit=no --num-callers=40"

library(ufoseq)
ufo_seq(1,10,1)

--19530-- WARNING: unhandled amd64-linux syscall: 323
--19530-- You may be able to write your own handler.
--19530-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--19530-- Nevertheless we consider this a bug.  Please report
--19530-- it at http://valgrind.org/support/bug_reports.html.
syscall/userfaultfd: Function not implemented
error initializing User-Fault file descriptor: Function not implemented
Error in ufo_seq(1, 10, 1) : Error initializing the UFO framework (-1)

This also happens when running ufoTest:

valgrind --track-origins=yes --keep-stacktraces=alloc-and-free --error-limit=no --num-callers=40 ./ufoTest 5

==22423== Memcheck, a memory error detector
==22423== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==22423== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==22423== Command: ./ufoTest 5
==22423== 
--22423-- WARNING: unhandled amd64-linux syscall: 323
--22423-- You may be able to write your own handler.
--22423-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--22423-- Nevertheless we consider this a bug.  Please report
--22423-- it at http://valgrind.org/support/bug_reports.html.
syscall/userfaultfd: Function not implemented
error initializing User-Fault file descriptor: Function not implemented
x.x: Function not implemented
Err Init: Function not implemented
==22423== 
==22423== HEAP SUMMARY:
==22423==     in use at exit: 82,208 bytes in 4 blocks
==22423==   total heap usage: 12 allocs, 8 frees, 88,512 bytes allocated
==22423== 
==22423== LEAK SUMMARY:
==22423==    definitely lost: 0 bytes in 0 blocks
==22423==    indirectly lost: 0 bytes in 0 blocks
==22423==      possibly lost: 0 bytes in 0 blocks
==22423==    still reachable: 82,208 bytes in 4 blocks
==22423==         suppressed: 0 bytes in 0 blocks
==22423== Rerun with --leak-check=full to see details of leaked memory
==22423== 
==22423== For counts of detected and suppressed errors, rerun with: -v
==22423== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

[kondziu]

I checked without valgrind.

__ufo_system = ufMakeInstance() returns 0x0, but ufInit(__ufo_system) returns result == 0

My understanding was that ufInit checks for NULL, but it turns out it doesn't. In fact ufMakeInstance should be checking for null before it starts allocating stuff inside the instance.

[electroCutie]

WARNING: unhandled amd64-linux syscall: 323

Reference for syscall numbers here: https://gist.github.com/yamnikov-oleg/454f48c3c45b735631f2
323 on amd64 is the userfaultd syscall
This line in our code is where it is called
int uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);

This is core and critical and cannot be avoided