Subject: SysV SHM never removed
To: NetBSD current-users mailing list <>
From: Julian Coleman <>
List: current-users
Date: 02/12/2000 16:04:31
I've turned the game netmaze into a package.  It uses shmget().
Unfortunately, I can only run it so many times before I get the error :

  shmget: Cannot allocate memory

The only way to clear this is to reboot.

With a few printf()'s in sys/kern/sysv_shm.c, I see : 

  shminfo.shmall is 1024 (on Sparc)

  shm_committed increases by 46 each time netmaze calls shmget()

  when netmaze exits, shmexit() is called, which calls shm_delete_mapping()

  shm_delete_mapping() does not call shm_deallocate_segment() because the
  test :

	if ((--shmseg->shm_nattch <= 0) &&
	    (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {

  fails.  printf()'s just before this test show :

    shmseg->shm_nattch = 1		This is OK.
    shmseg->shm_perm.mode = 0x980	Oops!  (SHMSEG_REMOVED is 0x400.)

What is the correct fix here?  Remove the check for & SHMSEG_REMOVED in
shm_delete_mapping(), or set |= SHMSEG_REMOVED in (say) shmexit(), or ...


PS.  Tested on Atari 1.4.1, Sparc 1.4.1 and Sparc 1.4R

                    My other computer also runs NetBSD