[Debconf-devel] Bug#764542: debconf: potential filesystem corruption

[Joey Hess]

westlake wrote:
> when there's low ram available and dpkg-reconfigure is issued (eg,
> dpkg-reconfigure locales), if there are premature "exits" when building
> locales it could lead to a filesystem corruption.
> 
> This happened to me more than once where I was using a 128MB ram for kvm,
> and there was less than 64 megs of ram available for dpkg-reconfigure..
> 
> I wouldn't expect filesystem corruption but there was something of it as I
> was forced to use fsck on boot-up.
> 
> There is a filesystem issue, I didn't want to believe it until it happened
> twice with two separate kvm VMs.  The disks are "virtual" isolating the
> diagnosis it could be a potential hardware problem. It could also be
> replicated more than once.
> 
> Steps
> ->dpkg-reconfigure locales would run but would have crash-exits when when
> trying to generate locales.
> 
> ->type "reboot". On the next boot-up there would be complaint of filesystem
> integrity and fsck would run.

If your system is experiencing sufficient memory pressue that things are
being OOM killed by the kernel, then it seems possible that could
interfere with the filesystem umount/read-only remounting or a process 
involved in running that during the reboot, thus leaving the filesystem
unclean (but probably without many other problems).

In any case, debconf is not responsible for anything that locales does
when reconfigured (it seems that locale-gen does need 100 mb of memory or
so to enable some locales, but I don't know why). And debconf does not
do anything unusual when accessing the filesystem (it would have to be
quite unusual indeed to corrupt it, on the order of writing to the
filesystem directly, bypassing the kernel). 

So, I'm fairly confident that if there's a bug at all, it's not in debconf.

-- 
see shy jo
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