On 04/07/2014 08:10 AM, Mel Gorman wrote:
> +/*
> + * Software bits ignored by the page table walker
> + * At the time of writing, different levels have bits that are ignored. Due
> + * to physical address limitations, bits 52:62 should be ignored for the PMD
> + * and PTE levels and are available for use by software. Be aware that this
> + * may change if the physical address space expands.
> + */
> +#define _PAGE_BIT_NUMA 62
Doesn't moving it up to the high bits break pte_modify()'s assumptions?
I was thinking of this nugget from change_pte_range():
ptent = ptep_modify_prot_start(mm, addr, pte);
if (pte_numa(ptent))
ptent = pte_mknonnuma(ptent);
ptent = pte_modify(ptent, newprot);
pte_modify() pulls off all the high bits out of 'ptent' and only adds
them back if they're in newprot (which as far as I can tell comes from
the VMA). So I _think_ it'll axe the _PAGE_NUMA out of 'ptent'.
--
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>