Linux 2.6.25.3

[linux/fpc-iii.git] / arch / powerpc / mm / numa.c

/*
 * pSeries NUMA support
 *
 * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <linux/threads.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <linux/nodemask.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <asm/sparsemem.h>
#include <asm/lmb.h>
#include <asm/system.h>
#include <asm/smp.h>

static int numa_enabled = 1;

static char *cmdline __initdata;

static int numa_debug;
#define dbg(args...) if (numa_debug) { printk(KERN_INFO args); }

int numa_cpu_lookup_table[NR_CPUS];
cpumask_t numa_cpumask_lookup_table[MAX_NUMNODES];
struct pglist_data *node_data[MAX_NUMNODES];

EXPORT_SYMBOL(numa_cpu_lookup_table);
EXPORT_SYMBOL(numa_cpumask_lookup_table);
EXPORT_SYMBOL(node_data);

static bootmem_data_t __initdata plat_node_bdata[MAX_NUMNODES];
static int min_common_depth;
static int n_mem_addr_cells, n_mem_size_cells;

static int __cpuinit fake_numa_create_new_node(unsigned long end_pfn,
                                                unsigned int *nid)
{
        unsigned long long mem;
        char *p = cmdline;
        static unsigned int fake_nid;
        static unsigned long long curr_boundary;

        /*
         * Modify node id, iff we started creating NUMA nodes
         * We want to continue from where we left of the last time
         */
        if (fake_nid)
                *nid = fake_nid;
        /*
         * In case there are no more arguments to parse, the
         * node_id should be the same as the last fake node id
         * (we've handled this above).
         */
        if (!p)
                return 0;

        mem = memparse(p, &p);
        if (!mem)
                return 0;

        if (mem < curr_boundary)
                return 0;

        curr_boundary = mem;

        if ((end_pfn << PAGE_SHIFT) > mem) {
                /*
                 * Skip commas and spaces
                 */
                while (*p == ',' || *p == ' ' || *p == '\t')
                        p++;

                cmdline = p;
                fake_nid++;
                *nid = fake_nid;
                dbg("created new fake_node with id %d\n", fake_nid);
                return 1;
        }
        return 0;
}

static void __cpuinit map_cpu_to_node(int cpu, int node)
{
        numa_cpu_lookup_table[cpu] = node;

        dbg("adding cpu %d to node %d\n", cpu, node);

        if (!(cpu_isset(cpu, numa_cpumask_lookup_table[node])))
                cpu_set(cpu, numa_cpumask_lookup_table[node]);
}

#ifdef CONFIG_HOTPLUG_CPU
static void unmap_cpu_from_node(unsigned long cpu)
{
        int node = numa_cpu_lookup_table[cpu];

        dbg("removing cpu %lu from node %d\n", cpu, node);

        if (cpu_isset(cpu, numa_cpumask_lookup_table[node])) {
                cpu_clear(cpu, numa_cpumask_lookup_table[node]);
        } else {
                printk(KERN_ERR "WARNING: cpu %lu not found in node %d\n",
                       cpu, node);
        }
}
#endif /* CONFIG_HOTPLUG_CPU */

static struct device_node * __cpuinit find_cpu_node(unsigned int cpu)
{
        unsigned int hw_cpuid = get_hard_smp_processor_id(cpu);
        struct device_node *cpu_node = NULL;
        const unsigned int *interrupt_server, *reg;
        int len;

        while ((cpu_node = of_find_node_by_type(cpu_node, "cpu")) != NULL) {
                /* Try interrupt server first */
                interrupt_server = of_get_property(cpu_node,
                                        "ibm,ppc-interrupt-server#s", &len);

                len = len / sizeof(u32);

                if (interrupt_server && (len > 0)) {
                        while (len--) {
                                if (interrupt_server[len] == hw_cpuid)
                                        return cpu_node;
                        }
                } else {
                        reg = of_get_property(cpu_node, "reg", &len);
                        if (reg && (len > 0) && (reg[0] == hw_cpuid))
                                return cpu_node;
                }
        }

        return NULL;
}

/* must hold reference to node during call */
static const int *of_get_associativity(struct device_node *dev)
{
        return of_get_property(dev, "ibm,associativity", NULL);
}

/* Returns nid in the range [0..MAX_NUMNODES-1], or -1 if no useful numa
 * info is found.
 */
static int of_node_to_nid_single(struct device_node *device)
{
        int nid = -1;
        const unsigned int *tmp;

        if (min_common_depth == -1)
                goto out;

        tmp = of_get_associativity(device);
        if (!tmp)
                goto out;

        if (tmp[0] >= min_common_depth)
                nid = tmp[min_common_depth];

        /* POWER4 LPAR uses 0xffff as invalid node */
        if (nid == 0xffff || nid >= MAX_NUMNODES)
                nid = -1;
out:
        return nid;
}

/* Walk the device tree upwards, looking for an associativity id */
int of_node_to_nid(struct device_node *device)
{
        struct device_node *tmp;
        int nid = -1;

        of_node_get(device);
        while (device) {
                nid = of_node_to_nid_single(device);
                if (nid != -1)
                        break;

                tmp = device;
                device = of_get_parent(tmp);
                of_node_put(tmp);
        }
        of_node_put(device);

        return nid;
}
EXPORT_SYMBOL_GPL(of_node_to_nid);

/*
 * In theory, the "ibm,associativity" property may contain multiple
 * associativity lists because a resource may be multiply connected
 * into the machine.  This resource then has different associativity
 * characteristics relative to its multiple connections.  We ignore
 * this for now.  We also assume that all cpu and memory sets have
 * their distances represented at a common level.  This won't be
 * true for hierarchical NUMA.
 *
 * In any case the ibm,associativity-reference-points should give
 * the correct depth for a normal NUMA system.
 *
 * - Dave Hansen <haveblue@us.ibm.com>
 */
static int __init find_min_common_depth(void)
{
        int depth;
        const unsigned int *ref_points;
        struct device_node *rtas_root;
        unsigned int len;

        rtas_root = of_find_node_by_path("/rtas");

        if (!rtas_root)
                return -1;

        /*
         * this property is 2 32-bit integers, each representing a level of
         * depth in the associativity nodes.  The first is for an SMP
         * configuration (should be all 0's) and the second is for a normal
         * NUMA configuration.
         */
        ref_points = of_get_property(rtas_root,
                        "ibm,associativity-reference-points", &len);

        if ((len >= 1) && ref_points) {
                depth = ref_points[1];
        } else {
                dbg("NUMA: ibm,associativity-reference-points not found.\n");
                depth = -1;
        }
        of_node_put(rtas_root);

        return depth;
}

static void __init get_n_mem_cells(int *n_addr_cells, int *n_size_cells)
{
        struct device_node *memory = NULL;

        memory = of_find_node_by_type(memory, "memory");
        if (!memory)
                panic("numa.c: No memory nodes found!");

        *n_addr_cells = of_n_addr_cells(memory);
        *n_size_cells = of_n_size_cells(memory);
        of_node_put(memory);
}

static unsigned long __devinit read_n_cells(int n, const unsigned int **buf)
{
        unsigned long result = 0;

        while (n--) {
                result = (result << 32) | **buf;
                (*buf)++;
        }
        return result;
}

/*
 * Figure out to which domain a cpu belongs and stick it there.
 * Return the id of the domain used.
 */
static int __cpuinit numa_setup_cpu(unsigned long lcpu)
{
        int nid = 0;
        struct device_node *cpu = find_cpu_node(lcpu);

        if (!cpu) {
                WARN_ON(1);
                goto out;
        }

        nid = of_node_to_nid_single(cpu);

        if (nid < 0 || !node_online(nid))
                nid = any_online_node(NODE_MASK_ALL);
out:
        map_cpu_to_node(lcpu, nid);

        of_node_put(cpu);

        return nid;
}

static int __cpuinit cpu_numa_callback(struct notifier_block *nfb,
                             unsigned long action,
                             void *hcpu)
{
        unsigned long lcpu = (unsigned long)hcpu;
        int ret = NOTIFY_DONE;

        switch (action) {
        case CPU_UP_PREPARE:
        case CPU_UP_PREPARE_FROZEN:
                numa_setup_cpu(lcpu);
                ret = NOTIFY_OK;
                break;
#ifdef CONFIG_HOTPLUG_CPU
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
        case CPU_UP_CANCELED:
        case CPU_UP_CANCELED_FROZEN:
                unmap_cpu_from_node(lcpu);
                break;
                ret = NOTIFY_OK;
#endif
        }
        return ret;
}

/*
 * Check and possibly modify a memory region to enforce the memory limit.
 *
 * Returns the size the region should have to enforce the memory limit.
 * This will either be the original value of size, a truncated value,
 * or zero. If the returned value of size is 0 the region should be
 * discarded as it lies wholy above the memory limit.
 */
static unsigned long __init numa_enforce_memory_limit(unsigned long start,
                                                      unsigned long size)
{
        /*
         * We use lmb_end_of_DRAM() in here instead of memory_limit because
         * we've already adjusted it for the limit and it takes care of
         * having memory holes below the limit.
         */

        if (! memory_limit)
                return size;

        if (start + size <= lmb_end_of_DRAM())
                return size;

        if (start >= lmb_end_of_DRAM())
                return 0;

        return lmb_end_of_DRAM() - start;
}

/*
 * Extract NUMA information from the ibm,dynamic-reconfiguration-memory
 * node.  This assumes n_mem_{addr,size}_cells have been set.
 */
static void __init parse_drconf_memory(struct device_node *memory)
{
        const unsigned int *lm, *dm, *aa;
        unsigned int ls, ld, la;
        unsigned int n, aam, aalen;
        unsigned long lmb_size, size, start;
        int nid, default_nid = 0;
        unsigned int ai, flags;

        lm = of_get_property(memory, "ibm,lmb-size", &ls);
        dm = of_get_property(memory, "ibm,dynamic-memory", &ld);
        aa = of_get_property(memory, "ibm,associativity-lookup-arrays", &la);
        if (!lm || !dm || !aa ||
            ls < sizeof(unsigned int) || ld < sizeof(unsigned int) ||
            la < 2 * sizeof(unsigned int))
                return;

        lmb_size = read_n_cells(n_mem_size_cells, &lm);
        n = *dm++;              /* number of LMBs */
        aam = *aa++;            /* number of associativity lists */
        aalen = *aa++;          /* length of each associativity list */
        if (ld < (n * (n_mem_addr_cells + 4) + 1) * sizeof(unsigned int) ||
            la < (aam * aalen + 2) * sizeof(unsigned int))
                return;

        for (; n != 0; --n) {
                start = read_n_cells(n_mem_addr_cells, &dm);
                ai = dm[2];
                flags = dm[3];
                dm += 4;
                /* 0x80 == reserved, 0x8 = assigned to us */
                if ((flags & 0x80) || !(flags & 0x8))
                        continue;
                nid = default_nid;
                /* flags & 0x40 means associativity index is invalid */
                if (min_common_depth > 0 && min_common_depth <= aalen &&
                    (flags & 0x40) == 0 && ai < aam) {
                        /* this is like of_node_to_nid_single */
                        nid = aa[ai * aalen + min_common_depth - 1];
                        if (nid == 0xffff || nid >= MAX_NUMNODES)
                                nid = default_nid;
                }

                fake_numa_create_new_node(((start + lmb_size) >> PAGE_SHIFT),
                                                &nid);
                node_set_online(nid);

                size = numa_enforce_memory_limit(start, lmb_size);
                if (!size)
                        continue;

                add_active_range(nid, start >> PAGE_SHIFT,
                                 (start >> PAGE_SHIFT) + (size >> PAGE_SHIFT));
        }
}

static int __init parse_numa_properties(void)
{
        struct device_node *cpu = NULL;
        struct device_node *memory = NULL;
        int default_nid = 0;
        unsigned long i;

        if (numa_enabled == 0) {
                printk(KERN_WARNING "NUMA disabled by user\n");
                return -1;
        }

        min_common_depth = find_min_common_depth();

        if (min_common_depth < 0)
                return min_common_depth;

        dbg("NUMA associativity depth for CPU/Memory: %d\n", min_common_depth);

        /*
         * Even though we connect cpus to numa domains later in SMP
         * init, we need to know the node ids now. This is because
         * each node to be onlined must have NODE_DATA etc backing it.
         */
        for_each_present_cpu(i) {
                int nid;

                cpu = find_cpu_node(i);
                BUG_ON(!cpu);
                nid = of_node_to_nid_single(cpu);
                of_node_put(cpu);

                /*
                 * Don't fall back to default_nid yet -- we will plug
                 * cpus into nodes once the memory scan has discovered
                 * the topology.
                 */
                if (nid < 0)
                        continue;
                node_set_online(nid);
        }

        get_n_mem_cells(&n_mem_addr_cells, &n_mem_size_cells);
        memory = NULL;
        while ((memory = of_find_node_by_type(memory, "memory")) != NULL) {
                unsigned long start;
                unsigned long size;
                int nid;
                int ranges;
                const unsigned int *memcell_buf;
                unsigned int len;

                memcell_buf = of_get_property(memory,
                        "linux,usable-memory", &len);
                if (!memcell_buf || len <= 0)
                        memcell_buf = of_get_property(memory, "reg", &len);
                if (!memcell_buf || len <= 0)
                        continue;

                /* ranges in cell */
                ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
new_range:
                /* these are order-sensitive, and modify the buffer pointer */
                start = read_n_cells(n_mem_addr_cells, &memcell_buf);
                size = read_n_cells(n_mem_size_cells, &memcell_buf);

                /*
                 * Assumption: either all memory nodes or none will
                 * have associativity properties.  If none, then
                 * everything goes to default_nid.
                 */
                nid = of_node_to_nid_single(memory);
                if (nid < 0)
                        nid = default_nid;

                fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);
                node_set_online(nid);

                if (!(size = numa_enforce_memory_limit(start, size))) {
                        if (--ranges)
                                goto new_range;
                        else
                                continue;
                }

                add_active_range(nid, start >> PAGE_SHIFT,
                                (start >> PAGE_SHIFT) + (size >> PAGE_SHIFT));

                if (--ranges)
                        goto new_range;
        }

        /*
         * Now do the same thing for each LMB listed in the ibm,dynamic-memory
         * property in the ibm,dynamic-reconfiguration-memory node.
         */
        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (memory)
                parse_drconf_memory(memory);

        return 0;
}

static void __init setup_nonnuma(void)
{
        unsigned long top_of_ram = lmb_end_of_DRAM();
        unsigned long total_ram = lmb_phys_mem_size();
        unsigned long start_pfn, end_pfn;
        unsigned int i, nid = 0;

        printk(KERN_DEBUG "Top of RAM: 0x%lx, Total RAM: 0x%lx\n",
               top_of_ram, total_ram);
        printk(KERN_DEBUG "Memory hole size: %ldMB\n",
               (top_of_ram - total_ram) >> 20);

        for (i = 0; i < lmb.memory.cnt; ++i) {
                start_pfn = lmb.memory.region[i].base >> PAGE_SHIFT;
                end_pfn = start_pfn + lmb_size_pages(&lmb.memory, i);

                fake_numa_create_new_node(end_pfn, &nid);
                add_active_range(nid, start_pfn, end_pfn);
                node_set_online(nid);
        }
}

void __init dump_numa_cpu_topology(void)
{
        unsigned int node;
        unsigned int cpu, count;

        if (min_common_depth == -1 || !numa_enabled)
                return;

        for_each_online_node(node) {
                printk(KERN_DEBUG "Node %d CPUs:", node);

                count = 0;
                /*
                 * If we used a CPU iterator here we would miss printing
                 * the holes in the cpumap.
                 */
                for (cpu = 0; cpu < NR_CPUS; cpu++) {
                        if (cpu_isset(cpu, numa_cpumask_lookup_table[node])) {
                                if (count == 0)
                                        printk(" %u", cpu);
                                ++count;
                        } else {
                                if (count > 1)
                                        printk("-%u", cpu - 1);
                                count = 0;
                        }
                }

                if (count > 1)
                        printk("-%u", NR_CPUS - 1);
                printk("\n");
        }
}

static void __init dump_numa_memory_topology(void)
{
        unsigned int node;
        unsigned int count;

        if (min_common_depth == -1 || !numa_enabled)
                return;

        for_each_online_node(node) {
                unsigned long i;

                printk(KERN_DEBUG "Node %d Memory:", node);

                count = 0;

                for (i = 0; i < lmb_end_of_DRAM();
                     i += (1 << SECTION_SIZE_BITS)) {
                        if (early_pfn_to_nid(i >> PAGE_SHIFT) == node) {
                                if (count == 0)
                                        printk(" 0x%lx", i);
                                ++count;
                        } else {
                                if (count > 0)
                                        printk("-0x%lx", i);
                                count = 0;
                        }
                }

                if (count > 0)
                        printk("-0x%lx", i);
                printk("\n");
        }
}

/*
 * Allocate some memory, satisfying the lmb or bootmem allocator where
 * required. nid is the preferred node and end is the physical address of
 * the highest address in the node.
 *
 * Returns the physical address of the memory.
 */
static void __init *careful_allocation(int nid, unsigned long size,
                                       unsigned long align,
                                       unsigned long end_pfn)
{
        int new_nid;
        unsigned long ret = __lmb_alloc_base(size, align, end_pfn << PAGE_SHIFT);

        /* retry over all memory */
        if (!ret)
                ret = __lmb_alloc_base(size, align, lmb_end_of_DRAM());

        if (!ret)
                panic("numa.c: cannot allocate %lu bytes on node %d",
                      size, nid);

        /*
         * If the memory came from a previously allocated node, we must
         * retry with the bootmem allocator.
         */
        new_nid = early_pfn_to_nid(ret >> PAGE_SHIFT);
        if (new_nid < nid) {
                ret = (unsigned long)__alloc_bootmem_node(NODE_DATA(new_nid),
                                size, align, 0);

                if (!ret)
                        panic("numa.c: cannot allocate %lu bytes on node %d",
                              size, new_nid);

                ret = __pa(ret);

                dbg("alloc_bootmem %lx %lx\n", ret, size);
        }

        return (void *)ret;
}

static struct notifier_block __cpuinitdata ppc64_numa_nb = {
        .notifier_call = cpu_numa_callback,
        .priority = 1 /* Must run before sched domains notifier. */
};

void __init do_init_bootmem(void)
{
        int nid;
        unsigned int i;

        min_low_pfn = 0;
        max_low_pfn = lmb_end_of_DRAM() >> PAGE_SHIFT;
        max_pfn = max_low_pfn;

        if (parse_numa_properties())
                setup_nonnuma();
        else
                dump_numa_memory_topology();

        register_cpu_notifier(&ppc64_numa_nb);
        cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
                          (void *)(unsigned long)boot_cpuid);

        for_each_online_node(nid) {
                unsigned long start_pfn, end_pfn;
                unsigned long bootmem_paddr;
                unsigned long bootmap_pages;

                get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);

                /* Allocate the node structure node local if possible */
                NODE_DATA(nid) = careful_allocation(nid,
                                        sizeof(struct pglist_data),
                                        SMP_CACHE_BYTES, end_pfn);
                NODE_DATA(nid) = __va(NODE_DATA(nid));
                memset(NODE_DATA(nid), 0, sizeof(struct pglist_data));

                dbg("node %d\n", nid);
                dbg("NODE_DATA() = %p\n", NODE_DATA(nid));

                NODE_DATA(nid)->bdata = &plat_node_bdata[nid];
                NODE_DATA(nid)->node_start_pfn = start_pfn;
                NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;

                if (NODE_DATA(nid)->node_spanned_pages == 0)
                        continue;

                dbg("start_paddr = %lx\n", start_pfn << PAGE_SHIFT);
                dbg("end_paddr = %lx\n", end_pfn << PAGE_SHIFT);

                bootmap_pages = bootmem_bootmap_pages(end_pfn - start_pfn);
                bootmem_paddr = (unsigned long)careful_allocation(nid,
                                        bootmap_pages << PAGE_SHIFT,
                                        PAGE_SIZE, end_pfn);
                memset(__va(bootmem_paddr), 0, bootmap_pages << PAGE_SHIFT);

                dbg("bootmap_paddr = %lx\n", bootmem_paddr);

                init_bootmem_node(NODE_DATA(nid), bootmem_paddr >> PAGE_SHIFT,
                                  start_pfn, end_pfn);

                free_bootmem_with_active_regions(nid, end_pfn);

                /* Mark reserved regions on this node */
                for (i = 0; i < lmb.reserved.cnt; i++) {
                        unsigned long physbase = lmb.reserved.region[i].base;
                        unsigned long size = lmb.reserved.region[i].size;
                        unsigned long start_paddr = start_pfn << PAGE_SHIFT;
                        unsigned long end_paddr = end_pfn << PAGE_SHIFT;

                        if (early_pfn_to_nid(physbase >> PAGE_SHIFT) != nid &&
                            early_pfn_to_nid((physbase+size-1) >> PAGE_SHIFT) != nid)
                                continue;

                        if (physbase < end_paddr &&
                            (physbase+size) > start_paddr) {
                                /* overlaps */
                                if (physbase < start_paddr) {
                                        size -= start_paddr - physbase;
                                        physbase = start_paddr;
                                }

                                if (size > end_paddr - physbase)
                                        size = end_paddr - physbase;

                                dbg("reserve_bootmem %lx %lx\n", physbase,
                                    size);
                                reserve_bootmem_node(NODE_DATA(nid), physbase,
                                                     size, BOOTMEM_DEFAULT);
                        }
                }

                sparse_memory_present_with_active_regions(nid);
        }
}

void __init paging_init(void)
{
        unsigned long max_zone_pfns[MAX_NR_ZONES];
        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
        max_zone_pfns[ZONE_DMA] = lmb_end_of_DRAM() >> PAGE_SHIFT;
        free_area_init_nodes(max_zone_pfns);
}

static int __init early_numa(char *p)
{
        if (!p)
                return 0;

        if (strstr(p, "off"))
                numa_enabled = 0;

        if (strstr(p, "debug"))
                numa_debug = 1;

        p = strstr(p, "fake=");
        if (p)
                cmdline = p + strlen("fake=");

        return 0;
}
early_param("numa", early_numa);

#ifdef CONFIG_MEMORY_HOTPLUG
/*
 * Find the node associated with a hot added memory section.  Section
 * corresponds to a SPARSEMEM section, not an LMB.  It is assumed that
 * sections are fully contained within a single LMB.
 */
int hot_add_scn_to_nid(unsigned long scn_addr)
{
        struct device_node *memory = NULL;
        nodemask_t nodes;
        int default_nid = any_online_node(NODE_MASK_ALL);
        int nid;

        if (!numa_enabled || (min_common_depth < 0))
                return default_nid;

        while ((memory = of_find_node_by_type(memory, "memory")) != NULL) {
                unsigned long start, size;
                int ranges;
                const unsigned int *memcell_buf;
                unsigned int len;

                memcell_buf = of_get_property(memory, "reg", &len);
                if (!memcell_buf || len <= 0)
                        continue;

                /* ranges in cell */
                ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
ha_new_range:
                start = read_n_cells(n_mem_addr_cells, &memcell_buf);
                size = read_n_cells(n_mem_size_cells, &memcell_buf);
                nid = of_node_to_nid_single(memory);

                /* Domains not present at boot default to 0 */
                if (nid < 0 || !node_online(nid))
                        nid = default_nid;

                if ((scn_addr >= start) && (scn_addr < (start + size))) {
                        of_node_put(memory);
                        goto got_nid;
                }

                if (--ranges)           /* process all ranges in cell */
                        goto ha_new_range;
        }
        BUG();  /* section address should be found above */
        return 0;

        /* Temporary code to ensure that returned node is not empty */
got_nid:
        nodes_setall(nodes);
        while (NODE_DATA(nid)->node_spanned_pages == 0) {
                node_clear(nid, nodes);
                nid = any_online_node(nodes);
        }
        return nid;
}
#endif /* CONFIG_MEMORY_HOTPLUG */