On 04/08/2014 06:09 AM, Mel Gorman wrote: > Using unused physical bits is something that will break eventually. > > Changelog since V1 > o Reuse software-bits > o Use paravirt ops when modifying PTEs in the NUMA helpers > > Aliasing _PAGE_NUMA and _PAGE_PROTNONE had some convenient properties but > it ultimately gave Xen a headache and pisses almost everybody off that > looks closely at it. Two discussions on "why this makes sense" is one > discussion too many so rather than having a third so here is this series. > This series reuses the PTE bits that are available to the programmer. > This adds some contraints on how and when automatic NUMA balancing can be > enabled but it should go away again when Xen stops using _PAGE_IOMAP. > > The series also converts the NUMA helpers to use paravirt-friendly operations > but it needs a Tested-by from the Xen and powerpc people. > It is proably simpler to just base this patchset on top of David Vrabel's which actually *does* remove _PAGE_IOMAP. David, is your patchset going to be pushed in this merge window as expected? That being said, these bits are precious, and if this ends up being a case where "only Xen needs another bit" once again then Xen should expect to get kicked to the curb at a moment's notice. -hpa -- 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>