ptrace on linux 2.6.12 causes oops

 it's on a tqm850l with mpc850. i've done the following:

in update_mmu_cache:

if (!PageReserved(page)
&& !test_bit(PG_arch_1, &page->flags)) {
// if (vma->vm_mm == current->active_mm){
// _tlbie(address);
// __flush_dcache_icache((void *) address);
// } else
__flush_dcache_icache(page _address(page));
// flush_dcache_icache_page(page);

set_bit(PG_arch_1, &page->flags);
}

like it is in ppc64. now it works. the flush_dcache_icache_page calls 
__flush_dcache_icache_phys, which temporary turns off the mmu for 
data-addressing. a bit strange i think. but unfortunately i have too less 
knowledge about kernel-internal ppc-stuff :(

anton