If task context switching occurs while a C function boundary has been exceeded, a SIGSEGV is generated.
The mruby revision is 572c674 .

• example ruby code

  Task.new do
    Module.new do
      sleep 0.1
    end
  end
  Task.new do
    sleep 0.1
  end
  Task.run

• build configuration file

  MRuby::Lockfile.disable rescue nil
  MRuby::Build.new do |conf|
    toolchain
    #enable_debug
    gem core: "mruby-bin-mruby"
    gem core: "mruby-task"
  end

• run

  % build/host/bin/mruby crash.rb
  zsh: segmentation fault (core dumped)  build/host/bin/mruby crash.rb

• run with conf.enable_debug

  % build/host/bin/mruby crash.rb
  Assertion failed: (c->ci == c->cibase || (c->ci - c->cibase) == cioff - 1), function mrb_vm_run, file /var/tmp/mruby/src/vm.c, line 1615.
  zsh: abort (core dumped)  build/host/bin/mruby crash.rb