On Mon, Aug 17, 2015 at 2:45 PM, Jerome Glisse <j.glisse@xxxxxxxxx> wrote: > On Fri, Aug 14, 2015 at 07:11:27PM -0700, Dan Williams wrote: >> Although it does not offer perfect protection if device memory is at a >> physically lower address than RAM, skipping the update of these >> variables does seem to be what we want. For example /dev/mem would >> fail to allow write access to persistent memory if it fails a >> valid_phys_addr_range() check. Since /dev/mem does not know how to >> write to PMEM in a reliably persistent way, it should not treat a >> PMEM-pfn like RAM. > > So i attach is a patch that should keep ZONE_DEVICE out of consideration > for the buddy allocator. You might also want to keep page reserved and not > free inside the zone, you could replace the generic_online_page() using > set_online_page_callback() while hotpluging device memory. > Hmm, are we already protected by the fact that ZONE_DEVICE is not represented in the GFP_ZONEMASK? -- 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>