Petr Vandrovec wrote:afaics, agp uses change_apge_attr() to turn on NOCACHE bit, and doesn't remove the mapping.
On Mon, Nov 10, 2003 at 06:17:37PM +0100, Manfred Spraul wrote:If the page is used by AGP, then it won't have a mapping either.
DEBUG_PAGEALLOC unmaps pages on kmem_cache_free and __free_pages(). The pages are mapped again during get_free_pages and kmem_cache_alloc.
0x86000 looks like a normal page - what guarantees that it's not used by the kernel?
With DEBUG_PAGEALLOC there is no problem with page if it is USED by the kernel.
Problem is if page is NOT USED - in this case kernel does not have it in its
mapping, and bad thing happen.