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Re: [Pkg-samba-maint] Default size limits for /run (/var/run) and /run/lock (/var/lock)

On Tue, Apr 12, 2011 at 08:19:59PM +0100, Roger Leigh wrote:
> On Tue, Apr 12, 2011 at 07:44:54AM -0700, Steve Langasek wrote:
> >  If the problem is that multiple tmpfs are mounted and
> > each can expand to half-of-RAM, either reduce the number of tmpfses
> > presented (as discussed), or limit the *whole* allocation for known mount
> > points to half-of-RAM and partition appropriately, or both.
> For this reason, I've adapted the patch to move /dev/shm to /run/shm;
> it's configurable whether this is a separate tmpfs mount, or simply
> a subdirectory of /run, and the size is also configurable as before
> (SHM_SIZE, with RAMSHM as the option to toggle the mounting).  We
> could additionally allow /tmp to be moved under /run/tmp, so that
> all existing tmpfs mounts could share a single tmpfs (I haven't
> done this yet).  Currently we mount a tmpfs on /tmp if RAMTMP=yes
> or root is mounted read-only, but we could move it under /run.

I should add here that while the other distributions have moved
/var/run and /var/lock under /run, they have not moved /dev/shm
or /tmp.  I'm not sure what the consensus is on doing either of
these, so I haven't put either into the proposed patch yet.

I think the question to answer here is whether or not /dev/shm
and /tmp offer the same lifetime policies as /var/run and /var/lock,
and whether or not they logically fit under the same heirarchy.
The first is clearly the case: they can all be on tmpfs.  Whether
they logically fit is not so clear.

I think that if we have /run/lock, /run/shm makes sense (how different
are locks and POSIX semaphores?  They are just a different type of
lock (broadly).  And shared memory is ephemeral state, just like
samba's state etc.).  So I would argue that it does fit.  But this
isn't a universally held opinion.  Is there any rationale against
doing this?

I'm not as sure about /run/tmp, though all the files under /run
are strictly temporary, they are pretty much all system files
rather than being owned by users (though /run/lock and /run/shm
would be user-writable;  however, there are proposals to restrict
access to /lock as on Fedora).


  .''`.  Roger Leigh
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