Hi David,

Thanks for the comments.

On Sun, 29 Jul 2007, David Miller wrote:

From: Mark Fortescue <redacted>
Date: Mon, 30 Jul 2007 03:18:42 +0100 (BST)

quoted

Unfortunatly Sparc32 sun4c low level memory management apears to be
incompatible with commit b6a2fea39318e43fee84fa7b0b90d68bed92d2ba
mm: variable length argument support.

For some reason, this commit corrupts the memory used by the low level
context/pte handling ring buffers in arch/sparc/mm/sun4c (in
add_ring_ordered, head->next becomes set to a NULL pointer).

I had a quick look at http://www.linux-mm.org to see if there were any
diagrams that show what is going on in the memory management systems, to
see if there was something that I could use to help me work out what is
going on, but I could not see any.

One possible issue is sequencing, perhaps the stack argument copy
is occuring before the new context is setup properly on sun4c.

I will see if I can generate some debug code to check out this posibility.

Another issue might be the new flush_cache_page() call in this
new code in fs/exec.c, there are now cases where flush_cache_page()
will be called on kernel addresses, and sun4c's implementation might
not like that at all.

I backed the commit out of my latest git pull (app 2am this morning) and I 
end up with a working kernel so this confirms that is is somthing 
specific to this patch.

I will try adding in a flush_cache_page() at an appropriate point on the 
pre-commit version of the code to see if that makes a mess of things.

Regards
 	Mark Fortescue.