linux-kernel - Re: BUG: Securityfs and bind mounts (2.6.34)

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Date:	Thu, 8 Jul 2010 07:43:17 -0700
From:	Greg KH <greg@...ah.com>
To:	Tvrtko Ursulin <tvrtko.ursulin@...hos.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: BUG: Securityfs and bind mounts (2.6.34)

On Thu, Jul 08, 2010 at 11:12:41AM +0100, Tvrtko Ursulin wrote:
> 
> Hi guys,
> 
> If I overlay a file in securityfs using mount --bind with a file from
> a regular filesystem, should I be allowed to rmmod the module which
> registered the overlaid securityfs file?

Why would you want to overlay securityfs in the first place?

And you might be able to rmmod the module, but I didn't think that
security modules were able to be unloaded anymore.

> I was able to do that, then I
> unmounted the bind mount, and then when attempting to unmount
> securityfs hit a BUG at
> fs/dcache.c:676 (see below). It would have made more sense to first
> umount the overlay file and then remove the module which registered
> with securityfs, nevertheless should kernel crash in this case?

Probably not, but then again, you did something that you shouldn't have,
so perhaps it is telling you not to do such a thing in the future :)

thanks,

greg k-h
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