#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/bit_spinlock.h>
#include <linux/page_cgroup.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/memory.h>
#include <linux/vmalloc.h>
#include <linux/cgroup.h>
#include <linux/swapops.h>
#include <linux/kmemleak.h>

static unsigned long total_usage;

#if !defined(CONFIG_SPARSEMEM)


void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
{
        pgdat->node_page_cgroup = NULL;
}

struct page_cgroup *lookup_page_cgroup(struct page *page)
{
        unsigned long pfn = page_to_pfn(page);
        unsigned long offset;
        struct page_cgroup *base;

        base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
#ifdef CONFIG_DEBUG_VM
        /*
         * The sanity checks the page allocator does upon freeing a
         * page can reach here before the page_cgroup arrays are
         * allocated when feeding a range of pages to the allocator
         * for the first time during bootup or memory hotplug.
         */
        if (unlikely(!base))
                return NULL;
#endif
        offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
        return base + offset;
}

static int __init alloc_node_page_cgroup(int nid)
{
        struct page_cgroup *base;
        unsigned long table_size;
        unsigned long nr_pages;

        nr_pages = NODE_DATA(nid)->node_spanned_pages;
        if (!nr_pages)
                return 0;

        table_size = sizeof(struct page_cgroup) * nr_pages;

        base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
                        table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
        if (!base)
                return -ENOMEM;
        NODE_DATA(nid)->node_page_cgroup = base;
        total_usage += table_size;
        return 0;
}

void __init page_cgroup_init_flatmem(void)
{

        int nid, fail;

        if (mem_cgroup_disabled())
                return;

        for_each_online_node(nid)  {
                fail = alloc_node_page_cgroup(nid);
                if (fail)
                        goto fail;
        }
        printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
        printk(KERN_INFO "please try 'cgroup_disable=memory' option if you"
        " don't want memory cgroups\n");
        invoke_page_ext_init_callbacks();
        return;
fail:
        printk(KERN_CRIT "allocation of page_cgroup failed.\n");
        printk(KERN_CRIT "please try 'cgroup_disable=memory' boot option\n");
        panic("Out of memory");
}

#else /* CONFIG_FLAT_NODE_MEM_MAP */

struct page_cgroup *lookup_page_cgroup(struct page *page)
{
        unsigned long pfn = page_to_pfn(page);
        struct mem_section *section = __pfn_to_section(pfn);
#ifdef CONFIG_DEBUG_VM
        /*
         * The sanity checks the page allocator does upon freeing a
         * page can reach here before the page_cgroup arrays are
         * allocated when feeding a range of pages to the allocator
         * for the first time during bootup or memory hotplug.
         */
        if (!section->page_cgroup)
                return NULL;
#endif
        return section->page_cgroup + pfn;
}

static void *__meminit alloc_page_cgroup(size_t size, int nid)
{
        gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
        void *addr = NULL;

        addr = alloc_pages_exact_nid(nid, size, flags);
        if (addr) {
                kmemleak_alloc(addr, size, 1, flags);
                return addr;
        }

        if (node_state(nid, N_HIGH_MEMORY))
                addr = vzalloc_node(size, nid);
        else
                addr = vzalloc(size);

        return addr;
}

static int __meminit init_section_page_cgroup(unsigned long pfn, int nid)
{
        struct mem_section *section;
        struct page_cgroup *base;
        unsigned long table_size;

        section = __pfn_to_section(pfn);

        if (section->page_cgroup)
                return 0;

        table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
        base = alloc_page_cgroup(table_size, nid);

        /*
         * The value stored in section->page_cgroup is (base - pfn)
         * and it does not point to the memory block allocated above,
         * causing kmemleak false positives.
         */
        kmemleak_not_leak(base);

        if (!base) {
                printk(KERN_ERR "page cgroup allocation failure\n");
                return -ENOMEM;
        }

        /*
         * The passed "pfn" may not be aligned to SECTION.  For the calculation
         * we need to apply a mask.
         */
        pfn &= PAGE_SECTION_MASK;
        section->page_cgroup = base - pfn;
        total_usage += table_size;
        return 0;
}
#ifdef CONFIG_MEMORY_HOTPLUG
static void free_page_cgroup(void *addr)
{
        if (is_vmalloc_addr(addr)) {
                vfree(addr);
        } else {
                struct page *page = virt_to_page(addr);
                size_t table_size =
                        sizeof(struct page_cgroup) * PAGES_PER_SECTION;

                BUG_ON(PageReserved(page));
                free_pages_exact(addr, table_size);
        }
}

void __free_page_cgroup(unsigned long pfn)
{
        struct mem_section *ms;
        struct page_cgroup *base;

        ms = __pfn_to_section(pfn);
        if (!ms || !ms->page_cgroup)
                return;
        base = ms->page_cgroup + pfn;
        free_page_cgroup(base);
        ms->page_cgroup = NULL;
}

int __meminit online_page_cgroup(unsigned long start_pfn,
                        unsigned long nr_pages,
                        int nid)
{
        unsigned long start, end, pfn;
        int fail = 0;

        start = SECTION_ALIGN_DOWN(start_pfn);
        end = SECTION_ALIGN_UP(start_pfn + nr_pages);

        if (nid == -1) {
                /*
                 * In this case, "nid" already exists and contains valid memory.
                 * "start_pfn" passed to us is a pfn which is an arg for
                 * online__pages(), and start_pfn should exist.
                 */
                nid = pfn_to_nid(start_pfn);
                VM_BUG_ON(!node_state(nid, N_ONLINE));
        }

        for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
                if (!pfn_present(pfn))
                        continue;
                fail = init_section_page_cgroup(pfn, nid);
        }
        if (!fail)
                return 0;

        /* rollback */
        for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
                __free_page_cgroup(pfn);

        return -ENOMEM;
}

int __meminit offline_page_cgroup(unsigned long start_pfn,
                unsigned long nr_pages, int nid)
{
        unsigned long start, end, pfn;

        start = SECTION_ALIGN_DOWN(start_pfn);
        end = SECTION_ALIGN_UP(start_pfn + nr_pages);

        for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
                __free_page_cgroup(pfn);
        return 0;

}

static int __meminit page_cgroup_callback(struct notifier_block *self,
                               unsigned long action, void *arg)
{
        struct memory_notify *mn = arg;
        int ret = 0;
        switch (action) {
        case MEM_GOING_ONLINE:
                ret = online_page_cgroup(mn->start_pfn,
                                   mn->nr_pages, mn->status_change_nid);
                break;
        case MEM_OFFLINE:
                offline_page_cgroup(mn->start_pfn,
                                mn->nr_pages, mn->status_change_nid);
                break;
        case MEM_CANCEL_ONLINE:
                offline_page_cgroup(mn->start_pfn,
                                mn->nr_pages, mn->status_change_nid);
                break;
        case MEM_GOING_OFFLINE:
                break;
        case MEM_ONLINE:
        case MEM_CANCEL_OFFLINE:
                break;
        }

        return notifier_from_errno(ret);
}

#endif

void __init page_cgroup_init(void)
{
        unsigned long pfn;
        int nid;

        if (mem_cgroup_disabled())
                return;

        for_each_node_state(nid, N_MEMORY) {
                unsigned long start_pfn, end_pfn;

                start_pfn = node_start_pfn(nid);
                end_pfn = node_end_pfn(nid);
                /*
                 * start_pfn and end_pfn may not be aligned to SECTION and the
                 * page->flags of out of node pages are not initialized.  So we
                 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
                 */
                for (pfn = start_pfn;
                     pfn < end_pfn;
                     pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {

                        if (!pfn_valid(pfn))
                                continue;
                        /*
                         * Nodes's pfns can be overlapping.
                         * We know some arch can have a nodes layout such as
                         * -------------pfn-------------->
                         * N0 | N1 | N2 | N0 | N1 | N2|....
                         * skip if this section starts in a higher node
                         */
                        if (early_pfn_to_nid(pfn) > nid)
                                continue;
                        if (init_section_page_cgroup(pfn, nid))
                                goto oom;
                }
        }
        hotplug_memory_notifier(page_cgroup_callback, 0);
        printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
        printk(KERN_INFO "please try 'cgroup_disable=memory' option if you "
                         "don't want memory cgroups\n");
        invoke_page_ext_init_callbacks();
        return;
oom:
        printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");
        panic("Out of memory");
}

void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
{
        return;
}

#endif


#ifdef CONFIG_MEMCG_SWAP

static DEFINE_MUTEX(swap_cgroup_mutex);
struct swap_cgroup_ctrl {
        struct page **map;
        unsigned long length;
        spinlock_t      lock;
};

static struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];

struct swap_cgroup {
        unsigned short          id;
};
#define SC_PER_PAGE     (PAGE_SIZE/sizeof(struct swap_cgroup))

/*
 * SwapCgroup implements "lookup" and "exchange" operations.
 * In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
 * against SwapCache. At swap_free(), this is accessed directly from swap.
 *
 * This means,
 *  - we have no race in "exchange" when we're accessed via SwapCache because
 *    SwapCache(and its swp_entry) is under lock.
 *  - When called via swap_free(), there is no user of this entry and no race.
 * Then, we don't need lock around "exchange".
 *
 * TODO: we can push these buffers out to HIGHMEM.
 */

/*
 * allocate buffer for swap_cgroup.
 */
static int swap_cgroup_prepare(int type)
{
        struct page *page;
        struct swap_cgroup_ctrl *ctrl;
        unsigned long idx, max;

        ctrl = &swap_cgroup_ctrl[type];

        for (idx = 0; idx < ctrl->length; idx++) {
                page = alloc_page(GFP_KERNEL | __GFP_ZERO);
                if (!page)
                        goto not_enough_page;
                ctrl->map[idx] = page;
        }
        return 0;
not_enough_page:
        max = idx;
        for (idx = 0; idx < max; idx++)
                __free_page(ctrl->map[idx]);

        return -ENOMEM;
}

static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
                                        struct swap_cgroup_ctrl **ctrlp)
{
        pgoff_t offset = swp_offset(ent);
        struct swap_cgroup_ctrl *ctrl;
        struct page *mappage;
        struct swap_cgroup *sc;

        ctrl = &swap_cgroup_ctrl[swp_type(ent)];
        if (ctrlp)
                *ctrlp = ctrl;

        mappage = ctrl->map[offset / SC_PER_PAGE];
        sc = page_address(mappage);
        return sc + offset % SC_PER_PAGE;
}

/**
 * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
 * @ent: swap entry to be cmpxchged
 * @old: old id
 * @new: new id
 *
 * Returns old id at success, 0 at failure.
 * (There is no mem_cgroup using 0 as its id)
 */
unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
                                        unsigned short old, unsigned short new)
{
        struct swap_cgroup_ctrl *ctrl;
        struct swap_cgroup *sc;
        unsigned long flags;
        unsigned short retval;

        sc = lookup_swap_cgroup(ent, &ctrl);

        spin_lock_irqsave(&ctrl->lock, flags);
        retval = sc->id;
        if (retval == old)
                sc->id = new;
        else
                retval = 0;
        spin_unlock_irqrestore(&ctrl->lock, flags);
        return retval;
}

/**
 * swap_cgroup_record - record mem_cgroup for this swp_entry.
 * @ent: swap entry to be recorded into
 * @id: mem_cgroup to be recorded
 *
 * Returns old value at success, 0 at failure.
 * (Of course, old value can be 0.)
 */
unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
{
        struct swap_cgroup_ctrl *ctrl;
        struct swap_cgroup *sc;
        unsigned short old;
        unsigned long flags;

        sc = lookup_swap_cgroup(ent, &ctrl);

        spin_lock_irqsave(&ctrl->lock, flags);
        old = sc->id;
        sc->id = id;
        spin_unlock_irqrestore(&ctrl->lock, flags);

        return old;
}

/**
 * lookup_swap_cgroup_id - lookup mem_cgroup id tied to swap entry
 * @ent: swap entry to be looked up.
 *
 * Returns CSS ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)
 */
unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
{
        return lookup_swap_cgroup(ent, NULL)->id;
}

int swap_cgroup_swapon(int type, unsigned long max_pages)
{
        void *array;
        unsigned long array_size;
        unsigned long length;
        struct swap_cgroup_ctrl *ctrl;

        if (!do_swap_account)
                return 0;

        length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
        array_size = length * sizeof(void *);

        array = vzalloc(array_size);
        if (!array)
                goto nomem;

        ctrl = &swap_cgroup_ctrl[type];
        mutex_lock(&swap_cgroup_mutex);
        ctrl->length = length;
        ctrl->map = array;
        spin_lock_init(&ctrl->lock);
        if (swap_cgroup_prepare(type)) {
                /* memory shortage */
                ctrl->map = NULL;
                ctrl->length = 0;
                mutex_unlock(&swap_cgroup_mutex);
                vfree(array);
                goto nomem;
        }
        mutex_unlock(&swap_cgroup_mutex);

        return 0;
nomem:
        printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
        printk(KERN_INFO
                "swap_cgroup can be disabled by swapaccount=0 boot option\n");
        return -ENOMEM;
}

void swap_cgroup_swapoff(int type)
{
        struct page **map;
        unsigned long i, length;
        struct swap_cgroup_ctrl *ctrl;

        if (!do_swap_account)
                return;

        mutex_lock(&swap_cgroup_mutex);
        ctrl = &swap_cgroup_ctrl[type];
        map = ctrl->map;
        length = ctrl->length;
        ctrl->map = NULL;
        ctrl->length = 0;
        mutex_unlock(&swap_cgroup_mutex);

        if (map) {
                for (i = 0; i < length; i++) {
                        struct page *page = map[i];
                        if (page)
                                __free_page(page);
                }
                vfree(map);
        }
}

#endif