Merge tag 'compiler-attributes-for-linus-v5.4' of git://github.com/ojeda/linux

[mirror_ubuntu-hirsute-kernel.git] / drivers / base / node.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Basic Node interface support
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/memory.h>
#include <linux/vmstat.h>
#include <linux/notifier.h>
#include <linux/node.h>
#include <linux/hugetlb.h>
#include <linux/compaction.h>
#include <linux/cpumask.h>
#include <linux/topology.h>
#include <linux/nodemask.h>
#include <linux/cpu.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>
#include <linux/swap.h>
#include <linux/slab.h>

static struct bus_type node_subsys = {
        .name = "node",
        .dev_name = "node",
};


static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf)
{
        ssize_t n;
        cpumask_var_t mask;
        struct node *node_dev = to_node(dev);

        /* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
        BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));

        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
                return 0;

        cpumask_and(mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
        n = cpumap_print_to_pagebuf(list, buf, mask);
        free_cpumask_var(mask);

        return n;
}

static inline ssize_t node_read_cpumask(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        return node_read_cpumap(dev, false, buf);
}
static inline ssize_t node_read_cpulist(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        return node_read_cpumap(dev, true, buf);
}

static DEVICE_ATTR(cpumap,  S_IRUGO, node_read_cpumask, NULL);
static DEVICE_ATTR(cpulist, S_IRUGO, node_read_cpulist, NULL);

/**
 * struct node_access_nodes - Access class device to hold user visible
 *                            relationships to other nodes.
 * @dev:        Device for this memory access class
 * @list_node:  List element in the node's access list
 * @access:     The access class rank
 * @hmem_attrs: Heterogeneous memory performance attributes
 */
struct node_access_nodes {
        struct device           dev;
        struct list_head        list_node;
        unsigned                access;
#ifdef CONFIG_HMEM_REPORTING
        struct node_hmem_attrs  hmem_attrs;
#endif
};
#define to_access_nodes(dev) container_of(dev, struct node_access_nodes, dev)

static struct attribute *node_init_access_node_attrs[] = {
        NULL,
};

static struct attribute *node_targ_access_node_attrs[] = {
        NULL,
};

static const struct attribute_group initiators = {
        .name   = "initiators",
        .attrs  = node_init_access_node_attrs,
};

static const struct attribute_group targets = {
        .name   = "targets",
        .attrs  = node_targ_access_node_attrs,
};

static const struct attribute_group *node_access_node_groups[] = {
        &initiators,
        &targets,
        NULL,
};

static void node_remove_accesses(struct node *node)
{
        struct node_access_nodes *c, *cnext;

        list_for_each_entry_safe(c, cnext, &node->access_list, list_node) {
                list_del(&c->list_node);
                device_unregister(&c->dev);
        }
}

static void node_access_release(struct device *dev)
{
        kfree(to_access_nodes(dev));
}

static struct node_access_nodes *node_init_node_access(struct node *node,
                                                       unsigned access)
{
        struct node_access_nodes *access_node;
        struct device *dev;

        list_for_each_entry(access_node, &node->access_list, list_node)
                if (access_node->access == access)
                        return access_node;

        access_node = kzalloc(sizeof(*access_node), GFP_KERNEL);
        if (!access_node)
                return NULL;

        access_node->access = access;
        dev = &access_node->dev;
        dev->parent = &node->dev;
        dev->release = node_access_release;
        dev->groups = node_access_node_groups;
        if (dev_set_name(dev, "access%u", access))
                goto free;

        if (device_register(dev))
                goto free_name;

        pm_runtime_no_callbacks(dev);
        list_add_tail(&access_node->list_node, &node->access_list);
        return access_node;
free_name:
        kfree_const(dev->kobj.name);
free:
        kfree(access_node);
        return NULL;
}

#ifdef CONFIG_HMEM_REPORTING
#define ACCESS_ATTR(name)                                                  \
static ssize_t name##_show(struct device *dev,                             \
                           struct device_attribute *attr,                  \
                           char *buf)                                      \
{                                                                          \
        return sprintf(buf, "%u\n", to_access_nodes(dev)->hmem_attrs.name); \
}                                                                          \
static DEVICE_ATTR_RO(name);

ACCESS_ATTR(read_bandwidth)
ACCESS_ATTR(read_latency)
ACCESS_ATTR(write_bandwidth)
ACCESS_ATTR(write_latency)

static struct attribute *access_attrs[] = {
        &dev_attr_read_bandwidth.attr,
        &dev_attr_read_latency.attr,
        &dev_attr_write_bandwidth.attr,
        &dev_attr_write_latency.attr,
        NULL,
};

/**
 * node_set_perf_attrs - Set the performance values for given access class
 * @nid: Node identifier to be set
 * @hmem_attrs: Heterogeneous memory performance attributes
 * @access: The access class the for the given attributes
 */
void node_set_perf_attrs(unsigned int nid, struct node_hmem_attrs *hmem_attrs,
                         unsigned access)
{
        struct node_access_nodes *c;
        struct node *node;
        int i;

        if (WARN_ON_ONCE(!node_online(nid)))
                return;

        node = node_devices[nid];
        c = node_init_node_access(node, access);
        if (!c)
                return;

        c->hmem_attrs = *hmem_attrs;
        for (i = 0; access_attrs[i] != NULL; i++) {
                if (sysfs_add_file_to_group(&c->dev.kobj, access_attrs[i],
                                            "initiators")) {
                        pr_info("failed to add performance attribute to node %d\n",
                                nid);
                        break;
                }
        }
}

/**
 * struct node_cache_info - Internal tracking for memory node caches
 * @dev:        Device represeting the cache level
 * @node:       List element for tracking in the node
 * @cache_attrs:Attributes for this cache level
 */
struct node_cache_info {
        struct device dev;
        struct list_head node;
        struct node_cache_attrs cache_attrs;
};
#define to_cache_info(device) container_of(device, struct node_cache_info, dev)

#define CACHE_ATTR(name, fmt)                                           \
static ssize_t name##_show(struct device *dev,                          \
                           struct device_attribute *attr,               \
                           char *buf)                                   \
{                                                                       \
        return sprintf(buf, fmt "\n", to_cache_info(dev)->cache_attrs.name);\
}                                                                       \
DEVICE_ATTR_RO(name);

CACHE_ATTR(size, "%llu")
CACHE_ATTR(line_size, "%u")
CACHE_ATTR(indexing, "%u")
CACHE_ATTR(write_policy, "%u")

static struct attribute *cache_attrs[] = {
        &dev_attr_indexing.attr,
        &dev_attr_size.attr,
        &dev_attr_line_size.attr,
        &dev_attr_write_policy.attr,
        NULL,
};
ATTRIBUTE_GROUPS(cache);

static void node_cache_release(struct device *dev)
{
        kfree(dev);
}

static void node_cacheinfo_release(struct device *dev)
{
        struct node_cache_info *info = to_cache_info(dev);
        kfree(info);
}

static void node_init_cache_dev(struct node *node)
{
        struct device *dev;

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return;

        dev->parent = &node->dev;
        dev->release = node_cache_release;
        if (dev_set_name(dev, "memory_side_cache"))
                goto free_dev;

        if (device_register(dev))
                goto free_name;

        pm_runtime_no_callbacks(dev);
        node->cache_dev = dev;
        return;
free_name:
        kfree_const(dev->kobj.name);
free_dev:
        kfree(dev);
}

/**
 * node_add_cache() - add cache attribute to a memory node
 * @nid: Node identifier that has new cache attributes
 * @cache_attrs: Attributes for the cache being added
 */
void node_add_cache(unsigned int nid, struct node_cache_attrs *cache_attrs)
{
        struct node_cache_info *info;
        struct device *dev;
        struct node *node;

        if (!node_online(nid) || !node_devices[nid])
                return;

        node = node_devices[nid];
        list_for_each_entry(info, &node->cache_attrs, node) {
                if (info->cache_attrs.level == cache_attrs->level) {
                        dev_warn(&node->dev,
                                "attempt to add duplicate cache level:%d\n",
                                cache_attrs->level);
                        return;
                }
        }

        if (!node->cache_dev)
                node_init_cache_dev(node);
        if (!node->cache_dev)
                return;

        info = kzalloc(sizeof(*info), GFP_KERNEL);
        if (!info)
                return;

        dev = &info->dev;
        dev->parent = node->cache_dev;
        dev->release = node_cacheinfo_release;
        dev->groups = cache_groups;
        if (dev_set_name(dev, "index%d", cache_attrs->level))
                goto free_cache;

        info->cache_attrs = *cache_attrs;
        if (device_register(dev)) {
                dev_warn(&node->dev, "failed to add cache level:%d\n",
                         cache_attrs->level);
                goto free_name;
        }
        pm_runtime_no_callbacks(dev);
        list_add_tail(&info->node, &node->cache_attrs);
        return;
free_name:
        kfree_const(dev->kobj.name);
free_cache:
        kfree(info);
}

static void node_remove_caches(struct node *node)
{
        struct node_cache_info *info, *next;

        if (!node->cache_dev)
                return;

        list_for_each_entry_safe(info, next, &node->cache_attrs, node) {
                list_del(&info->node);
                device_unregister(&info->dev);
        }
        device_unregister(node->cache_dev);
}

static void node_init_caches(unsigned int nid)
{
        INIT_LIST_HEAD(&node_devices[nid]->cache_attrs);
}
#else
static void node_init_caches(unsigned int nid) { }
static void node_remove_caches(struct node *node) { }
#endif

#define K(x) ((x) << (PAGE_SHIFT - 10))
static ssize_t node_read_meminfo(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        int n;
        int nid = dev->id;
        struct pglist_data *pgdat = NODE_DATA(nid);
        struct sysinfo i;
        unsigned long sreclaimable, sunreclaimable;

        si_meminfo_node(&i, nid);
        sreclaimable = node_page_state(pgdat, NR_SLAB_RECLAIMABLE);
        sunreclaimable = node_page_state(pgdat, NR_SLAB_UNRECLAIMABLE);
        n = sprintf(buf,
                       "Node %d MemTotal:       %8lu kB\n"
                       "Node %d MemFree:        %8lu kB\n"
                       "Node %d MemUsed:        %8lu kB\n"
                       "Node %d Active:         %8lu kB\n"
                       "Node %d Inactive:       %8lu kB\n"
                       "Node %d Active(anon):   %8lu kB\n"
                       "Node %d Inactive(anon): %8lu kB\n"
                       "Node %d Active(file):   %8lu kB\n"
                       "Node %d Inactive(file): %8lu kB\n"
                       "Node %d Unevictable:    %8lu kB\n"
                       "Node %d Mlocked:        %8lu kB\n",
                       nid, K(i.totalram),
                       nid, K(i.freeram),
                       nid, K(i.totalram - i.freeram),
                       nid, K(node_page_state(pgdat, NR_ACTIVE_ANON) +
                                node_page_state(pgdat, NR_ACTIVE_FILE)),
                       nid, K(node_page_state(pgdat, NR_INACTIVE_ANON) +
                                node_page_state(pgdat, NR_INACTIVE_FILE)),
                       nid, K(node_page_state(pgdat, NR_ACTIVE_ANON)),
                       nid, K(node_page_state(pgdat, NR_INACTIVE_ANON)),
                       nid, K(node_page_state(pgdat, NR_ACTIVE_FILE)),
                       nid, K(node_page_state(pgdat, NR_INACTIVE_FILE)),
                       nid, K(node_page_state(pgdat, NR_UNEVICTABLE)),
                       nid, K(sum_zone_node_page_state(nid, NR_MLOCK)));

#ifdef CONFIG_HIGHMEM
        n += sprintf(buf + n,
                       "Node %d HighTotal:      %8lu kB\n"
                       "Node %d HighFree:       %8lu kB\n"
                       "Node %d LowTotal:       %8lu kB\n"
                       "Node %d LowFree:        %8lu kB\n",
                       nid, K(i.totalhigh),
                       nid, K(i.freehigh),
                       nid, K(i.totalram - i.totalhigh),
                       nid, K(i.freeram - i.freehigh));
#endif
        n += sprintf(buf + n,
                       "Node %d Dirty:          %8lu kB\n"
                       "Node %d Writeback:      %8lu kB\n"
                       "Node %d FilePages:      %8lu kB\n"
                       "Node %d Mapped:         %8lu kB\n"
                       "Node %d AnonPages:      %8lu kB\n"
                       "Node %d Shmem:          %8lu kB\n"
                       "Node %d KernelStack:    %8lu kB\n"
                       "Node %d PageTables:     %8lu kB\n"
                       "Node %d NFS_Unstable:   %8lu kB\n"
                       "Node %d Bounce:         %8lu kB\n"
                       "Node %d WritebackTmp:   %8lu kB\n"
                       "Node %d KReclaimable:   %8lu kB\n"
                       "Node %d Slab:           %8lu kB\n"
                       "Node %d SReclaimable:   %8lu kB\n"
                       "Node %d SUnreclaim:     %8lu kB\n"
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
                       "Node %d AnonHugePages:  %8lu kB\n"
                       "Node %d ShmemHugePages: %8lu kB\n"
                       "Node %d ShmemPmdMapped: %8lu kB\n"
#endif
                        ,
                       nid, K(node_page_state(pgdat, NR_FILE_DIRTY)),
                       nid, K(node_page_state(pgdat, NR_WRITEBACK)),
                       nid, K(node_page_state(pgdat, NR_FILE_PAGES)),
                       nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
                       nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
                       nid, K(i.sharedram),
                       nid, sum_zone_node_page_state(nid, NR_KERNEL_STACK_KB),
                       nid, K(sum_zone_node_page_state(nid, NR_PAGETABLE)),
                       nid, K(node_page_state(pgdat, NR_UNSTABLE_NFS)),
                       nid, K(sum_zone_node_page_state(nid, NR_BOUNCE)),
                       nid, K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
                       nid, K(sreclaimable +
                              node_page_state(pgdat, NR_KERNEL_MISC_RECLAIMABLE)),
                       nid, K(sreclaimable + sunreclaimable),
                       nid, K(sreclaimable),
                       nid, K(sunreclaimable)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
                       ,
                       nid, K(node_page_state(pgdat, NR_ANON_THPS) *
                                       HPAGE_PMD_NR),
                       nid, K(node_page_state(pgdat, NR_SHMEM_THPS) *
                                       HPAGE_PMD_NR),
                       nid, K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED) *
                                       HPAGE_PMD_NR)
#endif
                       );
        n += hugetlb_report_node_meminfo(nid, buf + n);
        return n;
}

#undef K
static DEVICE_ATTR(meminfo, S_IRUGO, node_read_meminfo, NULL);

static ssize_t node_read_numastat(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        return sprintf(buf,
                       "numa_hit %lu\n"
                       "numa_miss %lu\n"
                       "numa_foreign %lu\n"
                       "interleave_hit %lu\n"
                       "local_node %lu\n"
                       "other_node %lu\n",
                       sum_zone_numa_state(dev->id, NUMA_HIT),
                       sum_zone_numa_state(dev->id, NUMA_MISS),
                       sum_zone_numa_state(dev->id, NUMA_FOREIGN),
                       sum_zone_numa_state(dev->id, NUMA_INTERLEAVE_HIT),
                       sum_zone_numa_state(dev->id, NUMA_LOCAL),
                       sum_zone_numa_state(dev->id, NUMA_OTHER));
}
static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);

static ssize_t node_read_vmstat(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        int nid = dev->id;
        struct pglist_data *pgdat = NODE_DATA(nid);
        int i;
        int n = 0;

        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
                n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
                             sum_zone_node_page_state(nid, i));

#ifdef CONFIG_NUMA
        for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
                n += sprintf(buf+n, "%s %lu\n",
                             vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
                             sum_zone_numa_state(nid, i));
#endif

        for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
                n += sprintf(buf+n, "%s %lu\n",
                             vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
                             NR_VM_NUMA_STAT_ITEMS],
                             node_page_state(pgdat, i));

        return n;
}
static DEVICE_ATTR(vmstat, S_IRUGO, node_read_vmstat, NULL);

static ssize_t node_read_distance(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        int nid = dev->id;
        int len = 0;
        int i;

        /*
         * buf is currently PAGE_SIZE in length and each node needs 4 chars
         * at the most (distance + space or newline).
         */
        BUILD_BUG_ON(MAX_NUMNODES * 4 > PAGE_SIZE);

        for_each_online_node(i)
                len += sprintf(buf + len, "%s%d", i ? " " : "", node_distance(nid, i));

        len += sprintf(buf + len, "\n");
        return len;
}
static DEVICE_ATTR(distance, S_IRUGO, node_read_distance, NULL);

static struct attribute *node_dev_attrs[] = {
        &dev_attr_cpumap.attr,
        &dev_attr_cpulist.attr,
        &dev_attr_meminfo.attr,
        &dev_attr_numastat.attr,
        &dev_attr_distance.attr,
        &dev_attr_vmstat.attr,
        NULL
};
ATTRIBUTE_GROUPS(node_dev);

#ifdef CONFIG_HUGETLBFS
/*
 * hugetlbfs per node attributes registration interface:
 * When/if hugetlb[fs] subsystem initializes [sometime after this module],
 * it will register its per node attributes for all online nodes with
 * memory.  It will also call register_hugetlbfs_with_node(), below, to
 * register its attribute registration functions with this node driver.
 * Once these hooks have been initialized, the node driver will call into
 * the hugetlb module to [un]register attributes for hot-plugged nodes.
 */
static node_registration_func_t __hugetlb_register_node;
static node_registration_func_t __hugetlb_unregister_node;

static inline bool hugetlb_register_node(struct node *node)
{
        if (__hugetlb_register_node &&
                        node_state(node->dev.id, N_MEMORY)) {
                __hugetlb_register_node(node);
                return true;
        }
        return false;
}

static inline void hugetlb_unregister_node(struct node *node)
{
        if (__hugetlb_unregister_node)
                __hugetlb_unregister_node(node);
}

void register_hugetlbfs_with_node(node_registration_func_t doregister,
                                  node_registration_func_t unregister)
{
        __hugetlb_register_node   = doregister;
        __hugetlb_unregister_node = unregister;
}
#else
static inline void hugetlb_register_node(struct node *node) {}

static inline void hugetlb_unregister_node(struct node *node) {}
#endif

static void node_device_release(struct device *dev)
{
        struct node *node = to_node(dev);

#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS)
        /*
         * We schedule the work only when a memory section is
         * onlined/offlined on this node. When we come here,
         * all the memory on this node has been offlined,
         * so we won't enqueue new work to this work.
         *
         * The work is using node->node_work, so we should
         * flush work before freeing the memory.
         */
        flush_work(&node->node_work);
#endif
        kfree(node);
}

/*
 * register_node - Setup a sysfs device for a node.
 * @num - Node number to use when creating the device.
 *
 * Initialize and register the node device.
 */
static int register_node(struct node *node, int num)
{
        int error;

        node->dev.id = num;
        node->dev.bus = &node_subsys;
        node->dev.release = node_device_release;
        node->dev.groups = node_dev_groups;
        error = device_register(&node->dev);

        if (error)
                put_device(&node->dev);
        else {
                hugetlb_register_node(node);

                compaction_register_node(node);
        }
        return error;
}

/**
 * unregister_node - unregister a node device
 * @node: node going away
 *
 * Unregisters a node device @node.  All the devices on the node must be
 * unregistered before calling this function.
 */
void unregister_node(struct node *node)
{
        hugetlb_unregister_node(node);          /* no-op, if memoryless node */
        node_remove_accesses(node);
        node_remove_caches(node);
        device_unregister(&node->dev);
}

struct node *node_devices[MAX_NUMNODES];

/*
 * register cpu under node
 */
int register_cpu_under_node(unsigned int cpu, unsigned int nid)
{
        int ret;
        struct device *obj;

        if (!node_online(nid))
                return 0;

        obj = get_cpu_device(cpu);
        if (!obj)
                return 0;

        ret = sysfs_create_link(&node_devices[nid]->dev.kobj,
                                &obj->kobj,
                                kobject_name(&obj->kobj));
        if (ret)
                return ret;

        return sysfs_create_link(&obj->kobj,
                                 &node_devices[nid]->dev.kobj,
                                 kobject_name(&node_devices[nid]->dev.kobj));
}

/**
 * register_memory_node_under_compute_node - link memory node to its compute
 *                                           node for a given access class.
 * @mem_nid:    Memory node number
 * @cpu_nid:    Cpu  node number
 * @access:     Access class to register
 *
 * Description:
 *      For use with platforms that may have separate memory and compute nodes.
 *      This function will export node relationships linking which memory
 *      initiator nodes can access memory targets at a given ranked access
 *      class.
 */
int register_memory_node_under_compute_node(unsigned int mem_nid,
                                            unsigned int cpu_nid,
                                            unsigned access)
{
        struct node *init_node, *targ_node;
        struct node_access_nodes *initiator, *target;
        int ret;

        if (!node_online(cpu_nid) || !node_online(mem_nid))
                return -ENODEV;

        init_node = node_devices[cpu_nid];
        targ_node = node_devices[mem_nid];
        initiator = node_init_node_access(init_node, access);
        target = node_init_node_access(targ_node, access);
        if (!initiator || !target)
                return -ENOMEM;

        ret = sysfs_add_link_to_group(&initiator->dev.kobj, "targets",
                                      &targ_node->dev.kobj,
                                      dev_name(&targ_node->dev));
        if (ret)
                return ret;

        ret = sysfs_add_link_to_group(&target->dev.kobj, "initiators",
                                      &init_node->dev.kobj,
                                      dev_name(&init_node->dev));
        if (ret)
                goto err;

        return 0;
 err:
        sysfs_remove_link_from_group(&initiator->dev.kobj, "targets",
                                     dev_name(&targ_node->dev));
        return ret;
}

int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
{
        struct device *obj;

        if (!node_online(nid))
                return 0;

        obj = get_cpu_device(cpu);
        if (!obj)
                return 0;

        sysfs_remove_link(&node_devices[nid]->dev.kobj,
                          kobject_name(&obj->kobj));
        sysfs_remove_link(&obj->kobj,
                          kobject_name(&node_devices[nid]->dev.kobj));

        return 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
static int __ref get_nid_for_pfn(unsigned long pfn)
{
        if (!pfn_valid_within(pfn))
                return -1;
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
        if (system_state < SYSTEM_RUNNING)
                return early_pfn_to_nid(pfn);
#endif
        return pfn_to_nid(pfn);
}

/* register memory section under specified node if it spans that node */
static int register_mem_sect_under_node(struct memory_block *mem_blk,
                                         void *arg)
{
        int ret, nid = *(int *)arg;
        unsigned long pfn, sect_start_pfn, sect_end_pfn;

        mem_blk->nid = nid;

        sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
        sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
        sect_end_pfn += PAGES_PER_SECTION - 1;
        for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
                int page_nid;

                /*
                 * memory block could have several absent sections from start.
                 * skip pfn range from absent section
                 */
                if (!pfn_present(pfn)) {
                        pfn = round_down(pfn + PAGES_PER_SECTION,
                                         PAGES_PER_SECTION) - 1;
                        continue;
                }

                /*
                 * We need to check if page belongs to nid only for the boot
                 * case, during hotplug we know that all pages in the memory
                 * block belong to the same node.
                 */
                if (system_state == SYSTEM_BOOTING) {
                        page_nid = get_nid_for_pfn(pfn);
                        if (page_nid < 0)
                                continue;
                        if (page_nid != nid)
                                continue;
                }
                ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
                                        &mem_blk->dev.kobj,
                                        kobject_name(&mem_blk->dev.kobj));
                if (ret)
                        return ret;

                return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
                                &node_devices[nid]->dev.kobj,
                                kobject_name(&node_devices[nid]->dev.kobj));
        }
        /* mem section does not span the specified node */
        return 0;
}

/*
 * Unregister memory block device under all nodes that it spans.
 * Has to be called with mem_sysfs_mutex held (due to unlinked_nodes).
 */
void unregister_memory_block_under_nodes(struct memory_block *mem_blk)
{
        unsigned long pfn, sect_start_pfn, sect_end_pfn;
        static nodemask_t unlinked_nodes;

        nodes_clear(unlinked_nodes);
        sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
        sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
        for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
                int nid;

                nid = get_nid_for_pfn(pfn);
                if (nid < 0)
                        continue;
                if (!node_online(nid))
                        continue;
                if (node_test_and_set(nid, unlinked_nodes))
                        continue;
                sysfs_remove_link(&node_devices[nid]->dev.kobj,
                         kobject_name(&mem_blk->dev.kobj));
                sysfs_remove_link(&mem_blk->dev.kobj,
                         kobject_name(&node_devices[nid]->dev.kobj));
        }
}

int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn)
{
        return walk_memory_blocks(PFN_PHYS(start_pfn),
                                  PFN_PHYS(end_pfn - start_pfn), (void *)&nid,
                                  register_mem_sect_under_node);
}

#ifdef CONFIG_HUGETLBFS
/*
 * Handle per node hstate attribute [un]registration on transistions
 * to/from memoryless state.
 */
static void node_hugetlb_work(struct work_struct *work)
{
        struct node *node = container_of(work, struct node, node_work);

        /*
         * We only get here when a node transitions to/from memoryless state.
         * We can detect which transition occurred by examining whether the
         * node has memory now.  hugetlb_register_node() already check this
         * so we try to register the attributes.  If that fails, then the
         * node has transitioned to memoryless, try to unregister the
         * attributes.
         */
        if (!hugetlb_register_node(node))
                hugetlb_unregister_node(node);
}

static void init_node_hugetlb_work(int nid)
{
        INIT_WORK(&node_devices[nid]->node_work, node_hugetlb_work);
}

static int node_memory_callback(struct notifier_block *self,
                                unsigned long action, void *arg)
{
        struct memory_notify *mnb = arg;
        int nid = mnb->status_change_nid;

        switch (action) {
        case MEM_ONLINE:
        case MEM_OFFLINE:
                /*
                 * offload per node hstate [un]registration to a work thread
                 * when transitioning to/from memoryless state.
                 */
                if (nid != NUMA_NO_NODE)
                        schedule_work(&node_devices[nid]->node_work);
                break;

        case MEM_GOING_ONLINE:
        case MEM_GOING_OFFLINE:
        case MEM_CANCEL_ONLINE:
        case MEM_CANCEL_OFFLINE:
        default:
                break;
        }

        return NOTIFY_OK;
}
#endif  /* CONFIG_HUGETLBFS */
#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */

#if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
    !defined(CONFIG_HUGETLBFS)
static inline int node_memory_callback(struct notifier_block *self,
                                unsigned long action, void *arg)
{
        return NOTIFY_OK;
}

static void init_node_hugetlb_work(int nid) { }

#endif

int __register_one_node(int nid)
{
        int error;
        int cpu;

        node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL);
        if (!node_devices[nid])
                return -ENOMEM;

        error = register_node(node_devices[nid], nid);

        /* link cpu under this node */
        for_each_present_cpu(cpu) {
                if (cpu_to_node(cpu) == nid)
                        register_cpu_under_node(cpu, nid);
        }

        INIT_LIST_HEAD(&node_devices[nid]->access_list);
        /* initialize work queue for memory hot plug */
        init_node_hugetlb_work(nid);
        node_init_caches(nid);

        return error;
}

void unregister_one_node(int nid)
{
        if (!node_devices[nid])
                return;

        unregister_node(node_devices[nid]);
        node_devices[nid] = NULL;
}

/*
 * node states attributes
 */

static ssize_t print_nodes_state(enum node_states state, char *buf)
{
        int n;

        n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl",
                      nodemask_pr_args(&node_states[state]));
        buf[n++] = '\n';
        buf[n] = '\0';
        return n;
}

struct node_attr {
        struct device_attribute attr;
        enum node_states state;
};

static ssize_t show_node_state(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct node_attr *na = container_of(attr, struct node_attr, attr);
        return print_nodes_state(na->state, buf);
}

#define _NODE_ATTR(name, state) \
        { __ATTR(name, 0444, show_node_state, NULL), state }

static struct node_attr node_state_attr[] = {
        [N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE),
        [N_ONLINE] = _NODE_ATTR(online, N_ONLINE),
        [N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY),
#ifdef CONFIG_HIGHMEM
        [N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY),
#endif
        [N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY),
        [N_CPU] = _NODE_ATTR(has_cpu, N_CPU),
};

static struct attribute *node_state_attrs[] = {
        &node_state_attr[N_POSSIBLE].attr.attr,
        &node_state_attr[N_ONLINE].attr.attr,
        &node_state_attr[N_NORMAL_MEMORY].attr.attr,
#ifdef CONFIG_HIGHMEM
        &node_state_attr[N_HIGH_MEMORY].attr.attr,
#endif
        &node_state_attr[N_MEMORY].attr.attr,
        &node_state_attr[N_CPU].attr.attr,
        NULL
};

static struct attribute_group memory_root_attr_group = {
        .attrs = node_state_attrs,
};

static const struct attribute_group *cpu_root_attr_groups[] = {
        &memory_root_attr_group,
        NULL,
};

#define NODE_CALLBACK_PRI       2       /* lower than SLAB */
static int __init register_node_type(void)
{
        int ret;

        BUILD_BUG_ON(ARRAY_SIZE(node_state_attr) != NR_NODE_STATES);
        BUILD_BUG_ON(ARRAY_SIZE(node_state_attrs)-1 != NR_NODE_STATES);

        ret = subsys_system_register(&node_subsys, cpu_root_attr_groups);
        if (!ret) {
                static struct notifier_block node_memory_callback_nb = {
                        .notifier_call = node_memory_callback,
                        .priority = NODE_CALLBACK_PRI,
                };
                register_hotmemory_notifier(&node_memory_callback_nb);
        }

        /*
         * Note:  we're not going to unregister the node class if we fail
         * to register the node state class attribute files.
         */
        return ret;
}
postcore_initcall(register_node_type);