rt_sigaction(SIGCHLD, {0x2b83ea5e7310, [CHLD], SA_RESTORER|SA_RESTART, 0x2b83ebd735d0}, {SIG_DFL}, 8) = 0
pipe([6, 9])                            = 0
pipe([10, 11])                          = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x2b83ec48f690) = 2607
write(9, "backtrace\n", 10)             = 10
write(9, "p x = 0\n", 8)                = 8
write(9, "quit\n", 5)                   = 5
select(1024, [10], NULL, NULL, {1, 0}) = ? ERESTARTNOHAND (To be restarted)
--- SIGCHLD (Child exited) @ 0 (0) ---
rt_sigreturn(0x11)                      = -1 EINTR (Interrupted system call)
close(6)                                = 0
close(9)                                = 0
close(10)                               = 0
close(11)                               = 0
exit_group(0)                           = ?