On 12/02/2015 02:03 PM, Dan Williams wrote: >>> >> Is pfn_valid() a reliable check? It seems to be based on a max_pfn >>> >> per node... what happens when pmem is located below that point. I >>> >> haven't been able to convince myself that we won't get false >>> >> positives, but maybe I'm missing something. >> > >> > With sparsemem at least, it makes sure that you're looking at a valid >> > _section_. See the pfn_valid() at ~include/linux/mmzone.h:1222. > At a minimum we would need to add "depends on SPARSEMEM" to "config FS_DAX_PMD". Yeah, it seems like an awful layering violation. But, sparsemem is turned on everywhere (all the distros/users) that we care about, as far as I know. -- 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>