page_cgroup.c

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#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");
    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:
    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_HIGH_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|....
             */
            if (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");
    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;
}

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;
}

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;
}

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