Re: 2.4.23 + tmpfs: where's my mem?!

[Hugh Dickins]

On Thu, 11 Dec 2003, Willy Tarreau wrote:

> On Thu, Dec 11, 2003 at 10:54:28AM -0200, dual_bereta_r0x wrote:
> > root@hquest:/tmp# cat /etc/slackware-version
> > Slackware 9.1.0
> > root@hquest:/tmp# uname -a
> > Linux hquest 2.4.23 #6 Sat Nov 29 22:47:03 PST 2003 i686 unknown unknown 
> > GNU/Linux
> > root@hquest:/tmp# df /tmp
> > Filesystem           1K-blocks      Used Available Use% Mounted on
> > tmpfs                   124024    112388     11636  91% /tmp
> > root@hquest:/tmp# du -s .
> > 32      .
> > root@hquest:/tmp# _
> 
> maybe you have a process which creates a temporary file in /tmp, and deletes
> the entry while keeping the fd open. vmware 1.2 did that, and probably more
> recent ones still do. It's a very clever way to automatically remove temp
> files when the process terminates.

That's right, and would explain why du may show 32 even if ls -alR
shows nothing at all (what does ls -alR /tmp show?).

But the strange thing is that df's Used does not match du: they should
be identical, though arrived at from different directions.  I've not
seen that, and have no idea what's going on: it's as if a subtree of
/tmp has become detached (a non-empty directory removed).

What usage led up to this?  What does /proc/meminfo show?
How many records out does "dd if=/dev/zero of=/tmp/zero bs=1k"
manage before /tmp fills up (11620 would fit df's Available,
the remaining 16k being metadata).

Hugh

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