Hi Peter, On 04/25/2013 06:51 AM, H. Peter Anvin wrote: > On 04/10/2013 01:02 AM, Minchan Kim wrote: >> When I am looking at the code, I was wonder about the logic of GHZP(aka, >> get_huge_zero_page) reference handling. The logic depends on that page >> allocator never alocate PFN 0. >> >> Who makes sure it? What happens if allocator allocates PFN 0? >> I don't know all of architecture makes sure it. >> You investigated it for all arches? >> > This isn't manifest, right? At least on x86 we should never, ever > allocate PFN 0. I see in memblock_trim_memory(): start = round_up(orig_start, align); here align is PAGE_SIZE, so the dump of zone ranges in my machine is [ 0.000000] DMA [mem 0x00001000-0x00ffffff]. Why PFN 0 is not used? just for align? > > -hpa > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org