[FFI] Segmentation fault when calling callback function

Description

The following code:

<?php
class Test {
   public $lib;
   public function __construct() {
      $this->lib = \FFI::cdef("extern void setCloseSessionCallback(void(*fun)(unsigned long cid));
      extern void testCloseSessionCallback();
      ", "./libsomelib.so");
   }
}

$tclass = new Test();
$tclass->lib->setCloseSessionCallback(function($cid){
   echo "ok\n";
});

$tclass->lib->testCloseSessionCallback(); //this function creates new std::thread from c++ stl, sleeps 2 seconds and calls function passed to setCloseSessionCallback
while(true); //prevent php script from completion because testCloseSessionCallback running in other thread

Resulted in this output:

segmentation fault (core dumped)

But I expected this output instead:

ok

gdb backtrace:

PHP Version

PHP 8.0.21 (zts) with Zend OPcache v8.0.21

Operating System

Manjaro Linux

Start with the PHP FFI reproduction in the issue, including the callback registered through libsomelib.so and the C++ thread that invokes it. Use the provided gdb backtrace while testing the PHP 8.0.21 ZTS setup on Manjaro Linux. Done means the callback prints "ok" without a segmentation fault.