Dear Maintainer,

   * What led up to the situation?

When I try to use the command 'dovecot dump username', it just hang
and unkillable by CTRL-C. Finally need to reboot to get rid of it.

   * What exactly did you do (or not do) that was effective (or
     ineffective)?

# jobs -l
[1]+  2447 Running                 doveadm dump username
      2448 Running                 | grep 'ref.*\b0\b' &  (wd: /home)

# strace -p 2447
strace: Process 2447 attached
futex(0x5622aae21730, FUTEX_WAIT_PRIVATE, 2, NULL <--hanging here

Thanks.