rpmdb and /var filesystem corruption in F7+

[Lennert Buytenhek]

On Thu, Sep 27, 2007 at 09:01:38AM -0600, Orion Poplawski wrote:

> I have a lot of problems with rpmdb corruption occurring during
> (network) installs since around February 2007, and with yum updates 
> afterwards.  I've reported the problem here 
> <https://bugzilla.redhat.com/show_bug.cgi?id=230362>.

I've been seeing rpmdb environment corruption on ARM systems (all
running >= 2.6.22) for a while now:

	https://www.redhat.com/archives/fedora-arm/2007-August/msg00007.html

The theory was that there is still some problem with shared writable
mmap()s, causing dirty pages to be dropped without being written out
to disk.  db4's data files are exclusively accessed via read()/write(),
but the database environment is exclusively accessed via mmap().

One shred of evidence that seems to point in this direction is that
I haven't seen this corruption occur on any of my ARM systems since
we started mlock()ing the RPM database environment into memory:

	http://fedora-arm.wantstofly.org/diffs-f/rpm-4.4.2.1-10.fc8/rpm-4.4.2-always-mlock.patch

One theory is that it might show up more on ARM systems because
they typically have less RAM and thus more memory pressure.