Re: PROBLEM: kernel BUG in buffer.c

From: Alan Cox (
Date: Wed Aug 21 2002 - 14:10:01 EST

On Wed, 2002-08-21 at 19:50, Peter Hicks wrote:
> Hi everyone
> I've come across a BUG() in buffer.c, line 2497. I'm running 2.4.19 on a
> Pentium III, with no other problems. I'd finished making a backup of an
> IRIX installation CD, was mounting the freshly burnt CD, and was greeted
> with a hung 'mount' and the following in dmesg:

Well its definitely a kernel bug. We should never crash given a bad CD.
In this case I think the problem is a little deeper. Our efs code
doesn't appear to consider and error the case when its block size is
below 2048 bytes.

An EFS block is 512 bytes so we tell a 2K sectored device to use 512byte
sectors. At this point the kernel rightfully realises that something
deeply wrong is happening and aborted.

I believe the fix is as follows

        Make EFS check its not asking for stupid block sizes
You can then use a loopback mount to buffer the device and mount the CD
that way. I'll fix the EFS code tomorrow

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