[releases.git] / numa.c

// SPDX-License-Identifier: GPL-2.0-only
/* Common code for 32 and 64-bit NUMA */
#include <linux/acpi.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/of.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/memblock.h>
#include <linux/mmzone.h>
#include <linux/ctype.h>
#include <linux/nodemask.h>
#include <linux/sched.h>
#include <linux/topology.h>
#include <linux/sort.h>

#include <asm/e820/api.h>
#include <asm/proto.h>
#include <asm/dma.h>
#include <asm/amd_nb.h>

#include "numa_internal.h"

int numa_off;
nodemask_t numa_nodes_parsed __initdata;

struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
EXPORT_SYMBOL(node_data);

static struct numa_meminfo numa_meminfo __initdata_or_meminfo;
static struct numa_meminfo numa_reserved_meminfo __initdata_or_meminfo;

static int numa_distance_cnt;
static u8 *numa_distance;

static __init int numa_setup(char *opt)
{
        if (!opt)
                return -EINVAL;
        if (!strncmp(opt, "off", 3))
                numa_off = 1;
        if (!strncmp(opt, "fake=", 5))
                return numa_emu_cmdline(opt + 5);
        if (!strncmp(opt, "noacpi", 6))
                disable_srat();
        if (!strncmp(opt, "nohmat", 6))
                disable_hmat();
        return 0;
}
early_param("numa", numa_setup);

/*
 * apicid, cpu, node mappings
 */
s16 __apicid_to_node[MAX_LOCAL_APIC] = {
        [0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
};

int numa_cpu_node(int cpu)
{
        u32 apicid = early_per_cpu(x86_cpu_to_apicid, cpu);

        if (apicid != BAD_APICID)
                return __apicid_to_node[apicid];
        return NUMA_NO_NODE;
}

cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
EXPORT_SYMBOL(node_to_cpumask_map);

/*
 * Map cpu index to node index
 */
DEFINE_EARLY_PER_CPU(int, x86_cpu_to_node_map, NUMA_NO_NODE);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_node_map);

void numa_set_node(int cpu, int node)
{
        int *cpu_to_node_map = early_per_cpu_ptr(x86_cpu_to_node_map);

        /* early setting, no percpu area yet */
        if (cpu_to_node_map) {
                cpu_to_node_map[cpu] = node;
                return;
        }

#ifdef CONFIG_DEBUG_PER_CPU_MAPS
        if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) {
                printk(KERN_ERR "numa_set_node: invalid cpu# (%d)\n", cpu);
                dump_stack();
                return;
        }
#endif
        per_cpu(x86_cpu_to_node_map, cpu) = node;

        set_cpu_numa_node(cpu, node);
}

void numa_clear_node(int cpu)
{
        numa_set_node(cpu, NUMA_NO_NODE);
}

/*
 * Allocate node_to_cpumask_map based on number of available nodes
 * Requires node_possible_map to be valid.
 *
 * Note: cpumask_of_node() is not valid until after this is done.
 * (Use CONFIG_DEBUG_PER_CPU_MAPS to check this.)
 */
void __init setup_node_to_cpumask_map(void)
{
        unsigned int node;

        /* setup nr_node_ids if not done yet */
        if (nr_node_ids == MAX_NUMNODES)
                setup_nr_node_ids();

        /* allocate the map */
        for (node = 0; node < nr_node_ids; node++)
                alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);

        /* cpumask_of_node() will now work */
        pr_debug("Node to cpumask map for %u nodes\n", nr_node_ids);
}

static int __init numa_add_memblk_to(int nid, u64 start, u64 end,
                                     struct numa_meminfo *mi)
{
        /* ignore zero length blks */
        if (start == end)
                return 0;

        /* whine about and ignore invalid blks */
        if (start > end || nid < 0 || nid >= MAX_NUMNODES) {
                pr_warn("Warning: invalid memblk node %d [mem %#010Lx-%#010Lx]\n",
                        nid, start, end - 1);
                return 0;
        }

        if (mi->nr_blks >= NR_NODE_MEMBLKS) {
                pr_err("too many memblk ranges\n");
                return -EINVAL;
        }

        mi->blk[mi->nr_blks].start = start;
        mi->blk[mi->nr_blks].end = end;
        mi->blk[mi->nr_blks].nid = nid;
        mi->nr_blks++;
        return 0;
}

/**
 * numa_remove_memblk_from - Remove one numa_memblk from a numa_meminfo
 * @idx: Index of memblk to remove
 * @mi: numa_meminfo to remove memblk from
 *
 * Remove @idx'th numa_memblk from @mi by shifting @mi->blk[] and
 * decrementing @mi->nr_blks.
 */
void __init numa_remove_memblk_from(int idx, struct numa_meminfo *mi)
{
        mi->nr_blks--;
        memmove(&mi->blk[idx], &mi->blk[idx + 1],
                (mi->nr_blks - idx) * sizeof(mi->blk[0]));
}

/**
 * numa_move_tail_memblk - Move a numa_memblk from one numa_meminfo to another
 * @dst: numa_meminfo to append block to
 * @idx: Index of memblk to remove
 * @src: numa_meminfo to remove memblk from
 */
static void __init numa_move_tail_memblk(struct numa_meminfo *dst, int idx,
                                         struct numa_meminfo *src)
{
        dst->blk[dst->nr_blks++] = src->blk[idx];
        numa_remove_memblk_from(idx, src);
}

/**
 * numa_add_memblk - Add one numa_memblk to numa_meminfo
 * @nid: NUMA node ID of the new memblk
 * @start: Start address of the new memblk
 * @end: End address of the new memblk
 *
 * Add a new memblk to the default numa_meminfo.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
int __init numa_add_memblk(int nid, u64 start, u64 end)
{
        return numa_add_memblk_to(nid, start, end, &numa_meminfo);
}

/* Allocate NODE_DATA for a node on the local memory */
static void __init alloc_node_data(int nid)
{
        const size_t nd_size = roundup(sizeof(pg_data_t), PAGE_SIZE);
        u64 nd_pa;
        void *nd;
        int tnid;

        /*
         * Allocate node data.  Try node-local memory and then any node.
         * Never allocate in DMA zone.
         */
        nd_pa = memblock_phys_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
        if (!nd_pa) {
                pr_err("Cannot find %zu bytes in any node (initial node: %d)\n",
                       nd_size, nid);
                return;
        }
        nd = __va(nd_pa);

        /* report and initialize */
        printk(KERN_INFO "NODE_DATA(%d) allocated [mem %#010Lx-%#010Lx]\n", nid,
               nd_pa, nd_pa + nd_size - 1);
        tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
        if (tnid != nid)
                printk(KERN_INFO "    NODE_DATA(%d) on node %d\n", nid, tnid);

        node_data[nid] = nd;
        memset(NODE_DATA(nid), 0, sizeof(pg_data_t));

        node_set_online(nid);
}

/**
 * numa_cleanup_meminfo - Cleanup a numa_meminfo
 * @mi: numa_meminfo to clean up
 *
 * Sanitize @mi by merging and removing unnecessary memblks.  Also check for
 * conflicts and clear unused memblks.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
int __init numa_cleanup_meminfo(struct numa_meminfo *mi)
{
        const u64 low = 0;
        const u64 high = PFN_PHYS(max_pfn);
        int i, j, k;

        /* first, trim all entries */
        for (i = 0; i < mi->nr_blks; i++) {
                struct numa_memblk *bi = &mi->blk[i];

                /* move / save reserved memory ranges */
                if (!memblock_overlaps_region(&memblock.memory,
                                        bi->start, bi->end - bi->start)) {
                        numa_move_tail_memblk(&numa_reserved_meminfo, i--, mi);
                        continue;
                }

                /* make sure all non-reserved blocks are inside the limits */
                bi->start = max(bi->start, low);

                /* preserve info for non-RAM areas above 'max_pfn': */
                if (bi->end > high) {
                        numa_add_memblk_to(bi->nid, high, bi->end,
                                           &numa_reserved_meminfo);
                        bi->end = high;
                }

                /* and there's no empty block */
                if (bi->start >= bi->end)
                        numa_remove_memblk_from(i--, mi);
        }

        /* merge neighboring / overlapping entries */
        for (i = 0; i < mi->nr_blks; i++) {
                struct numa_memblk *bi = &mi->blk[i];

                for (j = i + 1; j < mi->nr_blks; j++) {
                        struct numa_memblk *bj = &mi->blk[j];
                        u64 start, end;

                        /*
                         * See whether there are overlapping blocks.  Whine
                         * about but allow overlaps of the same nid.  They
                         * will be merged below.
                         */
                        if (bi->end > bj->start && bi->start < bj->end) {
                                if (bi->nid != bj->nid) {
                                        pr_err("node %d [mem %#010Lx-%#010Lx] overlaps with node %d [mem %#010Lx-%#010Lx]\n",
                                               bi->nid, bi->start, bi->end - 1,
                                               bj->nid, bj->start, bj->end - 1);
                                        return -EINVAL;
                                }
                                pr_warn("Warning: node %d [mem %#010Lx-%#010Lx] overlaps with itself [mem %#010Lx-%#010Lx]\n",
                                        bi->nid, bi->start, bi->end - 1,
                                        bj->start, bj->end - 1);
                        }

                        /*
                         * Join together blocks on the same node, holes
                         * between which don't overlap with memory on other
                         * nodes.
                         */
                        if (bi->nid != bj->nid)
                                continue;
                        start = min(bi->start, bj->start);
                        end = max(bi->end, bj->end);
                        for (k = 0; k < mi->nr_blks; k++) {
                                struct numa_memblk *bk = &mi->blk[k];

                                if (bi->nid == bk->nid)
                                        continue;
                                if (start < bk->end && end > bk->start)
                                        break;
                        }
                        if (k < mi->nr_blks)
                                continue;
                        printk(KERN_INFO "NUMA: Node %d [mem %#010Lx-%#010Lx] + [mem %#010Lx-%#010Lx] -> [mem %#010Lx-%#010Lx]\n",
                               bi->nid, bi->start, bi->end - 1, bj->start,
                               bj->end - 1, start, end - 1);
                        bi->start = start;
                        bi->end = end;
                        numa_remove_memblk_from(j--, mi);
                }
        }

        /* clear unused ones */
        for (i = mi->nr_blks; i < ARRAY_SIZE(mi->blk); i++) {
                mi->blk[i].start = mi->blk[i].end = 0;
                mi->blk[i].nid = NUMA_NO_NODE;
        }

        return 0;
}

/*
 * Set nodes, which have memory in @mi, in *@nodemask.
 */
static void __init numa_nodemask_from_meminfo(nodemask_t *nodemask,
                                              const struct numa_meminfo *mi)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(mi->blk); i++)
                if (mi->blk[i].start != mi->blk[i].end &&
                    mi->blk[i].nid != NUMA_NO_NODE)
                        node_set(mi->blk[i].nid, *nodemask);
}

/**
 * numa_reset_distance - Reset NUMA distance table
 *
 * The current table is freed.  The next numa_set_distance() call will
 * create a new one.
 */
void __init numa_reset_distance(void)
{
        size_t size = numa_distance_cnt * numa_distance_cnt * sizeof(numa_distance[0]);

        /* numa_distance could be 1LU marking allocation failure, test cnt */
        if (numa_distance_cnt)
                memblock_free(numa_distance, size);
        numa_distance_cnt = 0;
        numa_distance = NULL;   /* enable table creation */
}

static int __init numa_alloc_distance(void)
{
        nodemask_t nodes_parsed;
        size_t size;
        int i, j, cnt = 0;
        u64 phys;

        /* size the new table and allocate it */
        nodes_parsed = numa_nodes_parsed;
        numa_nodemask_from_meminfo(&nodes_parsed, &numa_meminfo);

        for_each_node_mask(i, nodes_parsed)
                cnt = i;
        cnt++;
        size = cnt * cnt * sizeof(numa_distance[0]);

        phys = memblock_phys_alloc_range(size, PAGE_SIZE, 0,
                                         PFN_PHYS(max_pfn_mapped));
        if (!phys) {
                pr_warn("Warning: can't allocate distance table!\n");
                /* don't retry until explicitly reset */
                numa_distance = (void *)1LU;
                return -ENOMEM;
        }

        numa_distance = __va(phys);
        numa_distance_cnt = cnt;

        /* fill with the default distances */
        for (i = 0; i < cnt; i++)
                for (j = 0; j < cnt; j++)
                        numa_distance[i * cnt + j] = i == j ?
                                LOCAL_DISTANCE : REMOTE_DISTANCE;
        printk(KERN_DEBUG "NUMA: Initialized distance table, cnt=%d\n", cnt);

        return 0;
}

/**
 * numa_set_distance - Set NUMA distance from one NUMA to another
 * @from: the 'from' node to set distance
 * @to: the 'to'  node to set distance
 * @distance: NUMA distance
 *
 * Set the distance from node @from to @to to @distance.  If distance table
 * doesn't exist, one which is large enough to accommodate all the currently
 * known nodes will be created.
 *
 * If such table cannot be allocated, a warning is printed and further
 * calls are ignored until the distance table is reset with
 * numa_reset_distance().
 *
 * If @from or @to is higher than the highest known node or lower than zero
 * at the time of table creation or @distance doesn't make sense, the call
 * is ignored.
 * This is to allow simplification of specific NUMA config implementations.
 */
void __init numa_set_distance(int from, int to, int distance)
{
        if (!numa_distance && numa_alloc_distance() < 0)
                return;

        if (from >= numa_distance_cnt || to >= numa_distance_cnt ||
                        from < 0 || to < 0) {
                pr_warn_once("Warning: node ids are out of bound, from=%d to=%d distance=%d\n",
                             from, to, distance);
                return;
        }

        if ((u8)distance != distance ||
            (from == to && distance != LOCAL_DISTANCE)) {
                pr_warn_once("Warning: invalid distance parameter, from=%d to=%d distance=%d\n",
                             from, to, distance);
                return;
        }

        numa_distance[from * numa_distance_cnt + to] = distance;
}

int __node_distance(int from, int to)
{
        if (from >= numa_distance_cnt || to >= numa_distance_cnt)
                return from == to ? LOCAL_DISTANCE : REMOTE_DISTANCE;
        return numa_distance[from * numa_distance_cnt + to];
}
EXPORT_SYMBOL(__node_distance);

/*
 * Sanity check to catch more bad NUMA configurations (they are amazingly
 * common).  Make sure the nodes cover all memory.
 */
static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
{
        u64 numaram, e820ram;
        int i;

        numaram = 0;
        for (i = 0; i < mi->nr_blks; i++) {
                u64 s = mi->blk[i].start >> PAGE_SHIFT;
                u64 e = mi->blk[i].end >> PAGE_SHIFT;
                numaram += e - s;
                numaram -= __absent_pages_in_range(mi->blk[i].nid, s, e);
                if ((s64)numaram < 0)
                        numaram = 0;
        }

        e820ram = max_pfn - absent_pages_in_range(0, max_pfn);

        /* We seem to lose 3 pages somewhere. Allow 1M of slack. */
        if ((s64)(e820ram - numaram) >= (1 << (20 - PAGE_SHIFT))) {
                printk(KERN_ERR "NUMA: nodes only cover %LuMB of your %LuMB e820 RAM. Not used.\n",
                       (numaram << PAGE_SHIFT) >> 20,
                       (e820ram << PAGE_SHIFT) >> 20);
                return false;
        }
        return true;
}

/*
 * Mark all currently memblock-reserved physical memory (which covers the
 * kernel's own memory ranges) as hot-unswappable.
 */
static void __init numa_clear_kernel_node_hotplug(void)
{
        nodemask_t reserved_nodemask = NODE_MASK_NONE;
        struct memblock_region *mb_region;
        int i;

        /*
         * We have to do some preprocessing of memblock regions, to
         * make them suitable for reservation.
         *
         * At this time, all memory regions reserved by memblock are
         * used by the kernel, but those regions are not split up
         * along node boundaries yet, and don't necessarily have their
         * node ID set yet either.
         *
         * So iterate over all memory known to the x86 architecture,
         * and use those ranges to set the nid in memblock.reserved.
         * This will split up the memblock regions along node
         * boundaries and will set the node IDs as well.
         */
        for (i = 0; i < numa_meminfo.nr_blks; i++) {
                struct numa_memblk *mb = numa_meminfo.blk + i;
                int ret;

                ret = memblock_set_node(mb->start, mb->end - mb->start, &memblock.reserved, mb->nid);
                WARN_ON_ONCE(ret);
        }

        /*
         * Now go over all reserved memblock regions, to construct a
         * node mask of all kernel reserved memory areas.
         *
         * [ Note, when booting with mem=nn[kMG] or in a kdump kernel,
         *   numa_meminfo might not include all memblock.reserved
         *   memory ranges, because quirks such as trim_snb_memory()
         *   reserve specific pages for Sandy Bridge graphics. ]
         */
        for_each_reserved_mem_region(mb_region) {
                int nid = memblock_get_region_node(mb_region);

                if (nid != MAX_NUMNODES)
                        node_set(nid, reserved_nodemask);
        }

        /*
         * Finally, clear the MEMBLOCK_HOTPLUG flag for all memory
         * belonging to the reserved node mask.
         *
         * Note that this will include memory regions that reside
         * on nodes that contain kernel memory - entire nodes
         * become hot-unpluggable:
         */
        for (i = 0; i < numa_meminfo.nr_blks; i++) {
                struct numa_memblk *mb = numa_meminfo.blk + i;

                if (!node_isset(mb->nid, reserved_nodemask))
                        continue;

                memblock_clear_hotplug(mb->start, mb->end - mb->start);
        }
}

static int __init numa_register_memblks(struct numa_meminfo *mi)
{
        int i, nid;

        /* Account for nodes with cpus and no memory */
        node_possible_map = numa_nodes_parsed;
        numa_nodemask_from_meminfo(&node_possible_map, mi);
        if (WARN_ON(nodes_empty(node_possible_map)))
                return -EINVAL;

        for (i = 0; i < mi->nr_blks; i++) {
                struct numa_memblk *mb = &mi->blk[i];
                memblock_set_node(mb->start, mb->end - mb->start,
                                  &memblock.memory, mb->nid);
        }

        /*
         * At very early time, the kernel have to use some memory such as
         * loading the kernel image. We cannot prevent this anyway. So any
         * node the kernel resides in should be un-hotpluggable.
         *
         * And when we come here, alloc node data won't fail.
         */
        numa_clear_kernel_node_hotplug();

        /*
         * If sections array is gonna be used for pfn -> nid mapping, check
         * whether its granularity is fine enough.
         */
        if (IS_ENABLED(NODE_NOT_IN_PAGE_FLAGS)) {
                unsigned long pfn_align = node_map_pfn_alignment();

                if (pfn_align && pfn_align < PAGES_PER_SECTION) {
                        pr_warn("Node alignment %LuMB < min %LuMB, rejecting NUMA config\n",
                                PFN_PHYS(pfn_align) >> 20,
                                PFN_PHYS(PAGES_PER_SECTION) >> 20);
                        return -EINVAL;
                }
        }
        if (!numa_meminfo_cover_memory(mi))
                return -EINVAL;

        /* Finally register nodes. */
        for_each_node_mask(nid, node_possible_map) {
                u64 start = PFN_PHYS(max_pfn);
                u64 end = 0;

                for (i = 0; i < mi->nr_blks; i++) {
                        if (nid != mi->blk[i].nid)
                                continue;
                        start = min(mi->blk[i].start, start);
                        end = max(mi->blk[i].end, end);
                }

                if (start >= end)
                        continue;

                alloc_node_data(nid);
        }

        /* Dump memblock with node info and return. */
        memblock_dump_all();
        return 0;
}

/*
 * There are unfortunately some poorly designed mainboards around that
 * only connect memory to a single CPU. This breaks the 1:1 cpu->node
 * mapping. To avoid this fill in the mapping for all possible CPUs,
 * as the number of CPUs is not known yet. We round robin the existing
 * nodes.
 */
static void __init numa_init_array(void)
{
        int rr, i;

        rr = first_node(node_online_map);
        for (i = 0; i < nr_cpu_ids; i++) {
                if (early_cpu_to_node(i) != NUMA_NO_NODE)
                        continue;
                numa_set_node(i, rr);
                rr = next_node_in(rr, node_online_map);
        }
}

static int __init numa_init(int (*init_func)(void))
{
        int i;
        int ret;

        for (i = 0; i < MAX_LOCAL_APIC; i++)
                set_apicid_to_node(i, NUMA_NO_NODE);

        nodes_clear(numa_nodes_parsed);
        nodes_clear(node_possible_map);
        nodes_clear(node_online_map);
        memset(&numa_meminfo, 0, sizeof(numa_meminfo));
        WARN_ON(memblock_set_node(0, ULLONG_MAX, &memblock.memory,
                                  MAX_NUMNODES));
        WARN_ON(memblock_set_node(0, ULLONG_MAX, &memblock.reserved,
                                  MAX_NUMNODES));
        /* In case that parsing SRAT failed. */
        WARN_ON(memblock_clear_hotplug(0, ULLONG_MAX));
        numa_reset_distance();

        ret = init_func();
        if (ret < 0)
                return ret;

        /*
         * We reset memblock back to the top-down direction
         * here because if we configured ACPI_NUMA, we have
         * parsed SRAT in init_func(). It is ok to have the
         * reset here even if we did't configure ACPI_NUMA
         * or acpi numa init fails and fallbacks to dummy
         * numa init.
         */
        memblock_set_bottom_up(false);

        ret = numa_cleanup_meminfo(&numa_meminfo);
        if (ret < 0)
                return ret;

        numa_emulation(&numa_meminfo, numa_distance_cnt);

        ret = numa_register_memblks(&numa_meminfo);
        if (ret < 0)
                return ret;

        for (i = 0; i < nr_cpu_ids; i++) {
                int nid = early_cpu_to_node(i);

                if (nid == NUMA_NO_NODE)
                        continue;
                if (!node_online(nid))
                        numa_clear_node(i);
        }
        numa_init_array();

        return 0;
}

/**
 * dummy_numa_init - Fallback dummy NUMA init
 *
 * Used if there's no underlying NUMA architecture, NUMA initialization
 * fails, or NUMA is disabled on the command line.
 *
 * Must online at least one node and add memory blocks that cover all
 * allowed memory.  This function must not fail.
 */
static int __init dummy_numa_init(void)
{
        printk(KERN_INFO "%s\n",
               numa_off ? "NUMA turned off" : "No NUMA configuration found");
        printk(KERN_INFO "Faking a node at [mem %#018Lx-%#018Lx]\n",
               0LLU, PFN_PHYS(max_pfn) - 1);

        node_set(0, numa_nodes_parsed);
        numa_add_memblk(0, 0, PFN_PHYS(max_pfn));

        return 0;
}

/**
 * x86_numa_init - Initialize NUMA
 *
 * Try each configured NUMA initialization method until one succeeds.  The
 * last fallback is dummy single node config encompassing whole memory and
 * never fails.
 */
void __init x86_numa_init(void)
{
        if (!numa_off) {
#ifdef CONFIG_ACPI_NUMA
                if (!numa_init(x86_acpi_numa_init))
                        return;
#endif
#ifdef CONFIG_AMD_NUMA
                if (!numa_init(amd_numa_init))
                        return;
#endif
                if (acpi_disabled && !numa_init(of_numa_init))
                        return;
        }

        numa_init(dummy_numa_init);
}


/*
 * A node may exist which has one or more Generic Initiators but no CPUs and no
 * memory.
 *
 * This function must be called after init_cpu_to_node(), to ensure that any
 * memoryless CPU nodes have already been brought online, and before the
 * node_data[nid] is needed for zone list setup in build_all_zonelists().
 *
 * When this function is called, any nodes containing either memory and/or CPUs
 * will already be online and there is no need to do anything extra, even if
 * they also contain one or more Generic Initiators.
 */
void __init init_gi_nodes(void)
{
        int nid;

        /*
         * Exclude this node from
         * bringup_nonboot_cpus
         *  cpu_up
         *   __try_online_node
         *    register_one_node
         * because node_subsys is not initialized yet.
         * TODO remove dependency on node_online
         */
        for_each_node_state(nid, N_GENERIC_INITIATOR)
                if (!node_online(nid))
                        node_set_online(nid);
}

/*
 * Setup early cpu_to_node.
 *
 * Populate cpu_to_node[] only if x86_cpu_to_apicid[],
 * and apicid_to_node[] tables have valid entries for a CPU.
 * This means we skip cpu_to_node[] initialisation for NUMA
 * emulation and faking node case (when running a kernel compiled
 * for NUMA on a non NUMA box), which is OK as cpu_to_node[]
 * is already initialized in a round robin manner at numa_init_array,
 * prior to this call, and this initialization is good enough
 * for the fake NUMA cases.
 *
 * Called before the per_cpu areas are setup.
 */
void __init init_cpu_to_node(void)
{
        int cpu;
        u32 *cpu_to_apicid = early_per_cpu_ptr(x86_cpu_to_apicid);

        BUG_ON(cpu_to_apicid == NULL);

        for_each_possible_cpu(cpu) {
                int node = numa_cpu_node(cpu);

                if (node == NUMA_NO_NODE)
                        continue;

                /*
                 * Exclude this node from
                 * bringup_nonboot_cpus
                 *  cpu_up
                 *   __try_online_node
                 *    register_one_node
                 * because node_subsys is not initialized yet.
                 * TODO remove dependency on node_online
                 */
                if (!node_online(node))
                        node_set_online(node);

                numa_set_node(cpu, node);
        }
}

#ifndef CONFIG_DEBUG_PER_CPU_MAPS

# ifndef CONFIG_NUMA_EMU
void numa_add_cpu(int cpu)
{
        cpumask_set_cpu(cpu, node_to_cpumask_map[early_cpu_to_node(cpu)]);
}

void numa_remove_cpu(int cpu)
{
        cpumask_clear_cpu(cpu, node_to_cpumask_map[early_cpu_to_node(cpu)]);
}
# endif /* !CONFIG_NUMA_EMU */

#else   /* !CONFIG_DEBUG_PER_CPU_MAPS */

int __cpu_to_node(int cpu)
{
        if (early_per_cpu_ptr(x86_cpu_to_node_map)) {
                printk(KERN_WARNING
                        "cpu_to_node(%d): usage too early!\n", cpu);
                dump_stack();
                return early_per_cpu_ptr(x86_cpu_to_node_map)[cpu];
        }
        return per_cpu(x86_cpu_to_node_map, cpu);
}
EXPORT_SYMBOL(__cpu_to_node);

/*
 * Same function as cpu_to_node() but used if called before the
 * per_cpu areas are setup.
 */
int early_cpu_to_node(int cpu)
{
        if (early_per_cpu_ptr(x86_cpu_to_node_map))
                return early_per_cpu_ptr(x86_cpu_to_node_map)[cpu];

        if (!cpu_possible(cpu)) {
                printk(KERN_WARNING
                        "early_cpu_to_node(%d): no per_cpu area!\n", cpu);
                dump_stack();
                return NUMA_NO_NODE;
        }
        return per_cpu(x86_cpu_to_node_map, cpu);
}

void debug_cpumask_set_cpu(int cpu, int node, bool enable)
{
        struct cpumask *mask;

        if (node == NUMA_NO_NODE) {
                /* early_cpu_to_node() already emits a warning and trace */
                return;
        }
        mask = node_to_cpumask_map[node];
        if (!cpumask_available(mask)) {
                pr_err("node_to_cpumask_map[%i] NULL\n", node);
                dump_stack();
                return;
        }

        if (enable)
                cpumask_set_cpu(cpu, mask);
        else
                cpumask_clear_cpu(cpu, mask);

        printk(KERN_DEBUG "%s cpu %d node %d: mask now %*pbl\n",
                enable ? "numa_add_cpu" : "numa_remove_cpu",
                cpu, node, cpumask_pr_args(mask));
        return;
}

# ifndef CONFIG_NUMA_EMU
static void numa_set_cpumask(int cpu, bool enable)
{
        debug_cpumask_set_cpu(cpu, early_cpu_to_node(cpu), enable);
}

void numa_add_cpu(int cpu)
{
        numa_set_cpumask(cpu, true);
}

void numa_remove_cpu(int cpu)
{
        numa_set_cpumask(cpu, false);
}
# endif /* !CONFIG_NUMA_EMU */

/*
 * Returns a pointer to the bitmask of CPUs on Node 'node'.
 */
const struct cpumask *cpumask_of_node(int node)
{
        if ((unsigned)node >= nr_node_ids) {
                printk(KERN_WARNING
                        "cpumask_of_node(%d): (unsigned)node >= nr_node_ids(%u)\n",
                        node, nr_node_ids);
                dump_stack();
                return cpu_none_mask;
        }
        if (!cpumask_available(node_to_cpumask_map[node])) {
                printk(KERN_WARNING
                        "cpumask_of_node(%d): no node_to_cpumask_map!\n",
                        node);
                dump_stack();
                return cpu_online_mask;
        }
        return node_to_cpumask_map[node];
}
EXPORT_SYMBOL(cpumask_of_node);

#endif  /* !CONFIG_DEBUG_PER_CPU_MAPS */

#ifdef CONFIG_NUMA_KEEP_MEMINFO
static int meminfo_to_nid(struct numa_meminfo *mi, u64 start)
{
        int i;

        for (i = 0; i < mi->nr_blks; i++)
                if (mi->blk[i].start <= start && mi->blk[i].end > start)
                        return mi->blk[i].nid;
        return NUMA_NO_NODE;
}

int phys_to_target_node(phys_addr_t start)
{
        int nid = meminfo_to_nid(&numa_meminfo, start);

        /*
         * Prefer online nodes, but if reserved memory might be
         * hot-added continue the search with reserved ranges.
         */
        if (nid != NUMA_NO_NODE)
                return nid;

        return meminfo_to_nid(&numa_reserved_meminfo, start);
}
EXPORT_SYMBOL_GPL(phys_to_target_node);

int memory_add_physaddr_to_nid(u64 start)
{
        int nid = meminfo_to_nid(&numa_meminfo, start);

        if (nid == NUMA_NO_NODE)
                nid = numa_meminfo.blk[0].nid;
        return nid;
}
EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);

static int __init cmp_memblk(const void *a, const void *b)
{
        const struct numa_memblk *ma = *(const struct numa_memblk **)a;
        const struct numa_memblk *mb = *(const struct numa_memblk **)b;

        return (ma->start > mb->start) - (ma->start < mb->start);
}

static struct numa_memblk *numa_memblk_list[NR_NODE_MEMBLKS] __initdata;

/**
 * numa_fill_memblks - Fill gaps in numa_meminfo memblks
 * @start: address to begin fill
 * @end: address to end fill
 *
 * Find and extend numa_meminfo memblks to cover the physical
 * address range @start-@end
 *
 * RETURNS:
 * 0              : Success
 * NUMA_NO_MEMBLK : No memblks exist in address range @start-@end
 */

int __init numa_fill_memblks(u64 start, u64 end)
{
        struct numa_memblk **blk = &numa_memblk_list[0];
        struct numa_meminfo *mi = &numa_meminfo;
        int count = 0;
        u64 prev_end;

        /*
         * Create a list of pointers to numa_meminfo memblks that
         * overlap start, end. The list is used to make in-place
         * changes that fill out the numa_meminfo memblks.
         */
        for (int i = 0; i < mi->nr_blks; i++) {
                struct numa_memblk *bi = &mi->blk[i];

                if (memblock_addrs_overlap(start, end - start, bi->start,
                                           bi->end - bi->start)) {
                        blk[count] = &mi->blk[i];
                        count++;
                }
        }
        if (!count)
                return NUMA_NO_MEMBLK;

        /* Sort the list of pointers in memblk->start order */
        sort(&blk[0], count, sizeof(blk[0]), cmp_memblk, NULL);

        /* Make sure the first/last memblks include start/end */
        blk[0]->start = min(blk[0]->start, start);
        blk[count - 1]->end = max(blk[count - 1]->end, end);

        /*
         * Fill any gaps by tracking the previous memblks
         * end address and backfilling to it if needed.
         */
        prev_end = blk[0]->end;
        for (int i = 1; i < count; i++) {
                struct numa_memblk *curr = blk[i];

                if (prev_end >= curr->start) {
                        if (prev_end < curr->end)
                                prev_end = curr->end;
                } else {
                        curr->start = prev_end;
                        prev_end = curr->end;
                }
        }
        return 0;
}

#endif