Messages in this thread | | | Date | Mon, 10 Nov 2003 21:36:53 +0200 | From | Mika Penttilä <> | Subject | Re: EFAULT reading /dev/mem... - broken x86info |
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Manfred Spraul wrote:
> Petr Vandrovec wrote: > >> On Mon, Nov 10, 2003 at 06:17:37PM +0100, Manfred Spraul wrote: >> >> >>> 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. >> >> > If the page is used by AGP, then it won't have a mapping either. > afaics, agp uses change_apge_attr() to turn on NOCACHE bit, and doesn't remove the mapping.
--Mika
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