On Wed, 3 Mar 2010, KAMEZAWA Hiroyuki wrote: > At node hot-add > > * pgdat is allocated from other node (because we have no memory for "nid") > * memmap for the first section (and possiby others) will be allocated from > other nodes. > * Once a section for the node is onlined, any memory can be allocated localy. > Correct, and the struct kmem_list3 is also alloacted from other nodes with my patch. > (Allocating memory from local node requires some new implementation as > bootmem allocater, we didn't that.) > > Before this patch, slab's control layer is allocated by cpuhotplug. > So, at least keeping this order, > memory online -> cpu online > slab's control layer is allocated from local node. > > When node-hotadd is done in this order > cpu online -> memory online > kmalloc_node() will allocate memory from other node via fallback. > > After this patch, slab's control layer is allocated by memory hotplug. > Then, in any order, slab's control will be allocated via fallback routine. > Again, this addresses memory hotplug that requires a new node to be onlined that do not have corresponding cpus that are being onlined. On x86, these represent ACPI_SRAT_MEM_HOT_PLUGGABLE regions that are onlined either by the acpi hotplug or done manually with CONFIG_ARCH_MEMORY_PROBE. On other architectures such as powerpc, this is done in different ways. All of this is spelled out in the changelog for the patch. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>