seg fault on dsm_create call

Hello.
I'm trying to understand how to work with dynamic shared memory, message
queues and workers.
The problem is I can not initialize a dsm segment -

     void _PG_init() {
         ...
         dsm_segment *seg = dsm_create(32768, 0); // Segmentation fault here
         ...
         BackgroundWorker worker;
         sprintf(worker.bgw_name, "mystem wrapper process");
         worker.bgw_flags = BGWORKER_SHMEM_ACCESS;
         worker.bgw_start_time = BgWorkerStart_RecoveryFinished;
         worker.bgw_restart_time = BGW_NEVER_RESTART;
         worker.bgw_main = mainProc;
         worker.bgw_notify_pid = 0;
         RegisterBackgroundWorker(&worker);
     }

Also I was trying to move dsm_create call to a worker, but with the same
result -

     static void mainProc(Datum) {
         ...
         dsm_segment *seg = dsm_create(32768, 0); // Segmentation fault here
         ...
         pqsignal(SIGTERM, mystemSigterm);
         BackgroundWorkerUnblockSignals();
         ...

What could be a reason and what am I doing wrong?

PS test/modules/test_shm_mq works fine...


--
Best regards,
Max Fomichev