On 03/16/2012 10:40 AM, Peter Zijlstra wrote: Reasonable idea, but we need something else than a blind unmap and add to swap space, which requires people to run with gigantic amounts of swap space they will likely never use. I suspect that Andrea's _PAGE_NUMA stuff could be implemented using _PAGE_PROTNONE, and then we can simply call the NUMA faulting/migration handler whenever we run into a _PAGE_PROTNONE page in handle_mm_fault / handle_pte_fault. This overloading of _PAGE_PROTNONE should work fine, because do_page_fault will never call handle_mm_fault if the fault is happening on a PROT_NONE VMA. Only if we have the correct VMA permission will handle_mm_fault be called, at which point we can fix the pte (and maybe migrate the page). The same trick can be done at the pmd level for transparent hugepages, allowing the entire THP to be migrated in one shot, with just one fault. Is there any reason why _PAGE_PROTNONE could not work instead of _PAGE_NUMA or the swap cache thing? -- All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>