On Fri, Mar 11, 2016 at 1:13 PM, Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx> wrote: > By moving the flag bits to the bottom, we encourage commonality > between SGs with pages and those using pfn_t. We can also then insert > a pfn_t into a radix tree, as it uses the same two bits for indirect & > exceptional indicators. It's not immediately clear to me what we gain with SG entry commonality. The down side is that we lose the property that pfn_to_pfn_t() is a nop. This was Dave's suggestion so that the nominal case did not change the binary layout of a typical pfn. Can we just bit swizzle a pfn_t on insertion/retrieval from the radix? -- 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>