linux-kernel - Re: Naughty ramdrives

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Message-ID: <20060907220559.GA29771@kroah.com>
Date:	Thu, 7 Sep 2006 15:05:59 -0700
From:	Greg KH <greg@...ah.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Alexey Dobriyan <adobriyan@...il.com>,
	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
	Christoph Hellwig <hch@....de>
Subject: Re: Naughty ramdrives

On Thu, Sep 07, 2006 at 02:54:12PM -0700, Andrew Morton wrote:
> On Fri, 8 Sep 2006 00:59:27 +0400
> Alexey Dobriyan <adobriyan@...il.com> wrote:
> 
> > You'd laugh, but...
> > 
> > Summary:
> > 
> > 	After loading and unloading rd.ko many times "ls -l /dev/ram*"
> > 	results are not persistent.
> > 
> > Steps to reproduce:
> > 
> > 	# while true; do modprobe rd && rmmod rd; done
> > 		[wait ~10 seconds]
> > 	^C
> > 	# modprobe rd
> > 
> > 	# ls -l /dev/ram*
> > 	lrwxrwxrwx 1 root root 5 Sep  8 00:35 /dev/ram12 -> rd/12
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram6 -> rd/6
> > 	# ls -l /dev/ram*
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram0 -> rd/0
> > 	lrwxrwxrwx 1 root root 5 Sep  8 00:35 /dev/ram13 -> rd/13
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram6 -> rd/6
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram7 -> rd/7
> > 	# ls -l /dev/ram*
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram0 -> rd/0
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram1 -> rd/1
> > 	lrwxrwxrwx 1 root root 5 Sep  8 00:35 /dev/ram11 -> rd/11
> > 	lrwxrwxrwx 1 root root 5 Sep  8 00:35 /dev/ram12 -> rd/12
> > 	lrwxrwxrwx 1 root root 5 Sep  8 00:35 /dev/ram14 -> rd/14
> > 	lrwxrwxrwx 1 root root 5 Sep  8 00:35 /dev/ram15 -> rd/15
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram3 -> rd/3
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram7 -> rd/7
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram8 -> rd/8
> > 	lrwxrwxrwx 1 root root 4 Sep  8 00:35 /dev/ram9 -> rd/9
> > 
> > Versions:
> > 
> > 	Linux 2.6.18-rc5
> > 	udev 087
> 
> So I assume udev is still madly crunching on its message backlog while
> this is happening?

It shouldn't be, this should not take that long.  Run 'udevmonitor' to
see what udev is doing at the moment to verify this or not.

> If so, ug.

I agree.  What distro is this?

I just tested this on my box running Gentoo and a newer version of udev
(099), and it worked just fine.  It took a while for udev to catch back
up with the flood of events, but it did and everything was fine.  No
harm done in the end.

thanks,

greg k-h
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