Subject: Re: SysV SHM never removed
To: Thilo Manske <Thilo.Manske@HEH.Uni-Oldenburg.DE>
From: Jason Thorpe <>
List: current-users
Date: 02/12/2000 09:30:21
On Sat, 12 Feb 2000 17:23:35 +0100 
 Thilo Manske <Thilo.Manske@HEH.Uni-Oldenburg.DE> wrote:

 > >   shmget: Cannot allocate memory
 > > 
 > > The only way to clear this is to reboot.
 > Workaround (instead of reboot):
 > You can try ipcs(1) & ipcrm(1) to manually remove shared memory segments,
 > e.g.
 > ipcs -m|grep ^m|awk '{ print $2 }'|xargs -n 1 ipcrm -m


Note, the semantics of SYSV IPC are that shared memory segments are NOT
removed when the process exists!  It's kind of like an in-memory shared
segment file system, of sorts.

Programs which create SHM segments *must* tear them down themselves!

I'm pretty sure this is documented in X/Open, and if I have time today,
I'll take a look.

        -- Jason R. Thorpe <>