Re: md as module cannot be reloaded.

[Neil Brown <neilb@suse.de>]

On Wed, 1 Dec 2010 14:23:14 +0000 "Hawrylewicz Czarnowski, Przemyslaw"
<przemyslaw.hawrylewicz.czarnowski@intel.com> wrote:

> Hi,
> 
> I have found an annoying problem with md module. If it is compiled as loadable module it is impossible to reload module if unloaded once.
> 
> Eg.
> # mdadm -Ss
> # modprobe -r raid1 && modprobe -r md-mod
> # cat /proc/modules | grep md_mod || echo Unloaded
> Unloaded
> # cat /proc/mdstat
> cat /proc/mdstat: Invalid arguments

I cannot reproduce this.  That this point I get 

cat: /proc/mdstat: No such file or directory


> # modprobe md-mod
> # cat /proc/mdstat
> cat /proc/mdstat: Invalid argument
> # cat /proc/modules | grep md_mod || echo Unloaded
> md_mod 94178 0 - Live 0xf857a000
> 
> Some functionalities seem to work, but nothing is able to read /proc/mdstat.
> 
> If have tried few kernels from 2.6.27 to 2.6.37-rc3, openSUSE 11.x/RHEL6, doesn't matter, still the same result. What can be wrong?

openSUSE doesn't compile md as a module, it is compiled in to the kernel.
But presumably you are compiling your own kernel with md as a module?  Is
that right?  You aren't compiling a module and loading it into a kernel which
already has md in it are you?  I don't think that would work anyway...

And you give a full sequence of commands from loading to unload that reliably
produces this error for you?

NeilBrown