/*
 * Copyright (c) Red Hat Inc.

 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors: Dave Airlie <airlied@redhat.com>
 *          Jerome Glisse <jglisse@redhat.com>
 *          Pauli Nieminen <suokkos@gmail.com>
 */
/*
 * Copyright (c) 2013 The FreeBSD Foundation
 * All rights reserved.
 *
 * Portions of this software were developed by Konstantin Belousov
 * <kib@FreeBSD.org> under sponsorship from the FreeBSD Foundation.
 */

/* simple list based uncached page pool
 * - Pool collects resently freed pages for reuse
 * - Use page->lru to keep a free list
 * - doesn't track currently in use pages
 */

#include <sys/cdefs.h>
#include <dev/drm2/drmP.h>
#include <dev/drm2/ttm/ttm_bo_driver.h>
#include <dev/drm2/ttm/ttm_page_alloc.h>
#include <sys/eventhandler.h>
#include <vm/vm_pageout.h>

#define NUM_PAGES_TO_ALLOC              (PAGE_SIZE/sizeof(vm_page_t))
#define SMALL_ALLOCATION                16
#define FREE_ALL_PAGES                  (~0U)
/* times are in msecs */
#define PAGE_FREE_INTERVAL              1000

/**
 * struct ttm_page_pool - Pool to reuse recently allocated uc/wc pages.
 *
 * @lock: Protects the shared pool from concurrnet access. Must be used with
 * irqsave/irqrestore variants because pool allocator maybe called from
 * delayed work.
 * @fill_lock: Prevent concurrent calls to fill.
 * @list: Pool of free uc/wc pages for fast reuse.
 * @gfp_flags: Flags to pass for alloc_page.
 * @npages: Number of pages in pool.
 */
struct ttm_page_pool {
        struct mtx              lock;
        bool                    fill_lock;
        bool                    dma32;
        struct pglist           list;
        int                     ttm_page_alloc_flags;
        unsigned                npages;
        char                    *name;
        unsigned long           nfrees;
        unsigned long           nrefills;
};

/**
 * Limits for the pool. They are handled without locks because only place where
 * they may change is in sysfs store. They won't have immediate effect anyway
 * so forcing serialization to access them is pointless.
 */

struct ttm_pool_opts {
        unsigned        alloc_size;
        unsigned        max_size;
        unsigned        small;
};

#define NUM_POOLS 4

/**
 * struct ttm_pool_manager - Holds memory pools for fst allocation
 *
 * Manager is read only object for pool code so it doesn't need locking.
 *
 * @free_interval: minimum number of jiffies between freeing pages from pool.
 * @page_alloc_inited: reference counting for pool allocation.
 * @work: Work that is used to shrink the pool. Work is only run when there is
 * some pages to free.
 * @small_allocation: Limit in number of pages what is small allocation.
 *
 * @pools: All pool objects in use.
 **/
struct ttm_pool_manager {
        unsigned int kobj_ref;
        eventhandler_tag lowmem_handler;
        struct ttm_pool_opts    options;

        union {
                struct ttm_page_pool    u_pools[NUM_POOLS];
                struct _utag {
                        struct ttm_page_pool    u_wc_pool;
                        struct ttm_page_pool    u_uc_pool;
                        struct ttm_page_pool    u_wc_pool_dma32;
                        struct ttm_page_pool    u_uc_pool_dma32;
                } _ut;
        } _u;
};

#define pools _u.u_pools
#define wc_pool _u._ut.u_wc_pool
#define uc_pool _u._ut.u_uc_pool
#define wc_pool_dma32 _u._ut.u_wc_pool_dma32
#define uc_pool_dma32 _u._ut.u_uc_pool_dma32

MALLOC_DEFINE(M_TTM_POOLMGR, "ttm_poolmgr", "TTM Pool Manager");

static void
ttm_vm_page_free(vm_page_t m)
{

        KASSERT(m->object == NULL, ("ttm page %p is owned", m));
        KASSERT(vm_page_wired(m), ("ttm lost wire %p", m));
        KASSERT((m->flags & PG_FICTITIOUS) != 0, ("ttm lost fictitious %p", m));
        KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("ttm got unmanaged %p", m));
        m->flags &= ~PG_FICTITIOUS;
        m->oflags |= VPO_UNMANAGED;
        vm_page_unwire_noq(m);
        vm_page_free(m);
}

static vm_memattr_t
ttm_caching_state_to_vm(enum ttm_caching_state cstate)
{

        switch (cstate) {
        case tt_uncached:
                return (VM_MEMATTR_UNCACHEABLE);
        case tt_wc:
                return (VM_MEMATTR_WRITE_COMBINING);
        case tt_cached:
                return (VM_MEMATTR_WRITE_BACK);
        }
        panic("caching state %d\n", cstate);
}

static vm_page_t
ttm_vm_page_alloc_dma32(int req, vm_memattr_t memattr)
{
        vm_page_t p;
        int err, tries;

        for (tries = 0; ; tries++) {
                p = vm_page_alloc_noobj_contig(req, 1, 0, 0xffffffff, PAGE_SIZE,
                    0, memattr);
                if (p != NULL || tries > 2)
                        return (p);
                err = vm_page_reclaim_contig(req, 1, 0, 0xffffffff,
                    PAGE_SIZE, 0);
                if (err == ENOMEM)
                        vm_wait(NULL);
                else if (err != 0)
                        return (NULL);
        }
}

static vm_page_t
ttm_vm_page_alloc_any(int req, vm_memattr_t memattr)
{
        vm_page_t p;

        p = vm_page_alloc_noobj(req | VM_ALLOC_WAITOK);
        pmap_page_set_memattr(p, memattr);
        return (p);
}

static vm_page_t
ttm_vm_page_alloc(int flags, enum ttm_caching_state cstate)
{
        vm_page_t p;
        vm_memattr_t memattr;
        int req;

        memattr = ttm_caching_state_to_vm(cstate);
        req = VM_ALLOC_WIRED;
        if ((flags & TTM_PAGE_FLAG_ZERO_ALLOC) != 0)
                req |= VM_ALLOC_ZERO;

        if ((flags & TTM_PAGE_FLAG_DMA32) != 0)
                p = ttm_vm_page_alloc_dma32(req, memattr);
        else
                p = ttm_vm_page_alloc_any(req, memattr);

        if (p != NULL) {
                p->oflags &= ~VPO_UNMANAGED;
                p->flags |= PG_FICTITIOUS;
        }
        return (p);
}

static void ttm_pool_kobj_release(struct ttm_pool_manager *m)
{

        free(m, M_TTM_POOLMGR);
}

#if 0
/* XXXKIB sysctl */
static ssize_t ttm_pool_store(struct ttm_pool_manager *m,
                struct attribute *attr, const char *buffer, size_t size)
{
        int chars;
        unsigned val;
        chars = sscanf(buffer, "%u", &val);
        if (chars == 0)
                return size;

        /* Convert kb to number of pages */
        val = val / (PAGE_SIZE >> 10);

        if (attr == &ttm_page_pool_max)
                m->options.max_size = val;
        else if (attr == &ttm_page_pool_small)
                m->options.small = val;
        else if (attr == &ttm_page_pool_alloc_size) {
                if (val > NUM_PAGES_TO_ALLOC*8) {
                        pr_err("Setting allocation size to %lu is not allowed. Recommended size is %lu\n",
                               NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 7),
                               NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
                        return size;
                } else if (val > NUM_PAGES_TO_ALLOC) {
                        pr_warn("Setting allocation size to larger than %lu is not recommended\n",
                                NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
                }
                m->options.alloc_size = val;
        }

        return size;
}

static ssize_t ttm_pool_show(struct ttm_pool_manager *m,
                struct attribute *attr, char *buffer)
{
        unsigned val = 0;

        if (attr == &ttm_page_pool_max)
                val = m->options.max_size;
        else if (attr == &ttm_page_pool_small)
                val = m->options.small;
        else if (attr == &ttm_page_pool_alloc_size)
                val = m->options.alloc_size;

        val = val * (PAGE_SIZE >> 10);

        return snprintf(buffer, PAGE_SIZE, "%u\n", val);
}
#endif

static struct ttm_pool_manager *_manager;

static int set_pages_array_wb(vm_page_t *pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
        int i;

        for (i = 0; i < addrinarray; i++)
                pmap_page_set_memattr(pages[i], VM_MEMATTR_WRITE_BACK);
#endif
        return 0;
}

static int set_pages_array_wc(vm_page_t *pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
        int i;

        for (i = 0; i < addrinarray; i++)
                pmap_page_set_memattr(pages[i], VM_MEMATTR_WRITE_COMBINING);
#endif
        return 0;
}

static int set_pages_array_uc(vm_page_t *pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
        int i;

        for (i = 0; i < addrinarray; i++)
                pmap_page_set_memattr(pages[i], VM_MEMATTR_UNCACHEABLE);
#endif
        return 0;
}

/**
 * Select the right pool or requested caching state and ttm flags. */
static struct ttm_page_pool *ttm_get_pool(int flags,
                enum ttm_caching_state cstate)
{
        int pool_index;

        if (cstate == tt_cached)
                return NULL;

        if (cstate == tt_wc)
                pool_index = 0x0;
        else
                pool_index = 0x1;

        if (flags & TTM_PAGE_FLAG_DMA32)
                pool_index |= 0x2;

        return &_manager->pools[pool_index];
}

/* set memory back to wb and free the pages. */
static void ttm_pages_put(vm_page_t *pages, unsigned npages)
{
        unsigned i;

        /* Our VM handles vm memattr automatically on the page free. */
        if (set_pages_array_wb(pages, npages))
                printf("[TTM] Failed to set %d pages to wb!\n", npages);
        for (i = 0; i < npages; ++i)
                ttm_vm_page_free(pages[i]);
}

static void ttm_pool_update_free_locked(struct ttm_page_pool *pool,
                unsigned freed_pages)
{
        pool->npages -= freed_pages;
        pool->nfrees += freed_pages;
}

/**
 * Free pages from pool.
 *
 * To prevent hogging the ttm_swap process we only free NUM_PAGES_TO_ALLOC
 * number of pages in one go.
 *
 * @pool: to free the pages from
 * @free_all: If set to true will free all pages in pool
 **/
static int ttm_page_pool_free(struct ttm_page_pool *pool, unsigned nr_free)
{
        vm_page_t p, p1;
        vm_page_t *pages_to_free;
        unsigned freed_pages = 0,
                 npages_to_free = nr_free;
        unsigned i;

        if (NUM_PAGES_TO_ALLOC < nr_free)
                npages_to_free = NUM_PAGES_TO_ALLOC;

        pages_to_free = malloc(npages_to_free * sizeof(vm_page_t),
            M_TEMP, M_WAITOK | M_ZERO);

restart:
        mtx_lock(&pool->lock);

        TAILQ_FOREACH_REVERSE_SAFE(p, &pool->list, pglist, plinks.q, p1) {
                if (freed_pages >= npages_to_free)
                        break;

                pages_to_free[freed_pages++] = p;
                /* We can only remove NUM_PAGES_TO_ALLOC at a time. */
                if (freed_pages >= NUM_PAGES_TO_ALLOC) {
                        /* remove range of pages from the pool */
                        for (i = 0; i < freed_pages; i++)
                                TAILQ_REMOVE(&pool->list, pages_to_free[i], plinks.q);

                        ttm_pool_update_free_locked(pool, freed_pages);
                        /**
                         * Because changing page caching is costly
                         * we unlock the pool to prevent stalling.
                         */
                        mtx_unlock(&pool->lock);

                        ttm_pages_put(pages_to_free, freed_pages);
                        if (likely(nr_free != FREE_ALL_PAGES))
                                nr_free -= freed_pages;

                        if (NUM_PAGES_TO_ALLOC >= nr_free)
                                npages_to_free = nr_free;
                        else
                                npages_to_free = NUM_PAGES_TO_ALLOC;

                        freed_pages = 0;

                        /* free all so restart the processing */
                        if (nr_free)
                                goto restart;

                        /* Not allowed to fall through or break because
                         * following context is inside spinlock while we are
                         * outside here.
                         */
                        goto out;

                }
        }

        /* remove range of pages from the pool */
        if (freed_pages) {
                for (i = 0; i < freed_pages; i++)
                        TAILQ_REMOVE(&pool->list, pages_to_free[i], plinks.q);

                ttm_pool_update_free_locked(pool, freed_pages);
                nr_free -= freed_pages;
        }

        mtx_unlock(&pool->lock);

        if (freed_pages)
                ttm_pages_put(pages_to_free, freed_pages);
out:
        free(pages_to_free, M_TEMP);
        return nr_free;
}

/* Get good estimation how many pages are free in pools */
static int ttm_pool_get_num_unused_pages(void)
{
        unsigned i;
        int total = 0;
        for (i = 0; i < NUM_POOLS; ++i)
                total += _manager->pools[i].npages;

        return total;
}

/**
 * Callback for mm to request pool to reduce number of page held.
 */
static int ttm_pool_mm_shrink(void *arg, int flags __unused)
{
        static unsigned int start_pool = 0;
        unsigned i;
        unsigned pool_offset = atomic_fetchadd_int(&start_pool, 1);
        struct ttm_page_pool *pool;
        int shrink_pages = 100; /* XXXKIB */

        pool_offset = pool_offset % NUM_POOLS;
        /* select start pool in round robin fashion */
        for (i = 0; i < NUM_POOLS; ++i) {
                unsigned nr_free = shrink_pages;
                if (shrink_pages == 0)
                        break;
                pool = &_manager->pools[(i + pool_offset)%NUM_POOLS];
                shrink_pages = ttm_page_pool_free(pool, nr_free);
        }
        /* return estimated number of unused pages in pool */
        return ttm_pool_get_num_unused_pages();
}

static void ttm_pool_mm_shrink_init(struct ttm_pool_manager *manager)
{

        manager->lowmem_handler = EVENTHANDLER_REGISTER(vm_lowmem,
            ttm_pool_mm_shrink, manager, EVENTHANDLER_PRI_ANY);
}

static void ttm_pool_mm_shrink_fini(struct ttm_pool_manager *manager)
{

        EVENTHANDLER_DEREGISTER(vm_lowmem, manager->lowmem_handler);
}

static int ttm_set_pages_caching(vm_page_t *pages,
                enum ttm_caching_state cstate, unsigned cpages)
{
        int r = 0;
        /* Set page caching */
        switch (cstate) {
        case tt_uncached:
                r = set_pages_array_uc(pages, cpages);
                if (r)
                        printf("[TTM] Failed to set %d pages to uc!\n", cpages);
                break;
        case tt_wc:
                r = set_pages_array_wc(pages, cpages);
                if (r)
                        printf("[TTM] Failed to set %d pages to wc!\n", cpages);
                break;
        default:
                break;
        }
        return r;
}

/**
 * Free pages the pages that failed to change the caching state. If there is
 * any pages that have changed their caching state already put them to the
 * pool.
 */
static void ttm_handle_caching_state_failure(struct pglist *pages,
                int ttm_flags, enum ttm_caching_state cstate,
                vm_page_t *failed_pages, unsigned cpages)
{
        unsigned i;
        /* Failed pages have to be freed */
        for (i = 0; i < cpages; ++i) {
                TAILQ_REMOVE(pages, failed_pages[i], plinks.q);
                ttm_vm_page_free(failed_pages[i]);
        }
}

/**
 * Allocate new pages with correct caching.
 *
 * This function is reentrant if caller updates count depending on number of
 * pages returned in pages array.
 */
static int ttm_alloc_new_pages(struct pglist *pages, int ttm_alloc_flags,
                int ttm_flags, enum ttm_caching_state cstate, unsigned count)
{
        vm_page_t *caching_array;
        vm_page_t p;
        int r = 0;
        unsigned i, cpages;
        unsigned max_cpages = min(count,
                        (unsigned)(PAGE_SIZE/sizeof(vm_page_t)));

        /* allocate array for page caching change */
        caching_array = malloc(max_cpages * sizeof(vm_page_t), M_TEMP,
            M_WAITOK | M_ZERO);

        for (i = 0, cpages = 0; i < count; ++i) {
                p = ttm_vm_page_alloc(ttm_alloc_flags, cstate);
                if (!p) {
                        printf("[TTM] Unable to get page %u\n", i);

                        /* store already allocated pages in the pool after
                         * setting the caching state */
                        if (cpages) {
                                r = ttm_set_pages_caching(caching_array,
                                                          cstate, cpages);
                                if (r)
                                        ttm_handle_caching_state_failure(pages,
                                                ttm_flags, cstate,
                                                caching_array, cpages);
                        }
                        r = -ENOMEM;
                        goto out;
                }

#ifdef CONFIG_HIGHMEM /* KIB: nop */
                /* gfp flags of highmem page should never be dma32 so we
                 * we should be fine in such case
                 */
                if (!PageHighMem(p))
#endif
                {
                        caching_array[cpages++] = p;
                        if (cpages == max_cpages) {

                                r = ttm_set_pages_caching(caching_array,
                                                cstate, cpages);
                                if (r) {
                                        ttm_handle_caching_state_failure(pages,
                                                ttm_flags, cstate,
                                                caching_array, cpages);
                                        goto out;
                                }
                                cpages = 0;
                        }
                }

                TAILQ_INSERT_HEAD(pages, p, plinks.q);
        }

        if (cpages) {
                r = ttm_set_pages_caching(caching_array, cstate, cpages);
                if (r)
                        ttm_handle_caching_state_failure(pages,
                                        ttm_flags, cstate,
                                        caching_array, cpages);
        }
out:
        free(caching_array, M_TEMP);

        return r;
}

/**
 * Fill the given pool if there aren't enough pages and the requested number of
 * pages is small.
 */
static void ttm_page_pool_fill_locked(struct ttm_page_pool *pool,
    int ttm_flags, enum ttm_caching_state cstate, unsigned count)
{
        vm_page_t p;
        int r;
        unsigned cpages = 0;
        /**
         * Only allow one pool fill operation at a time.
         * If pool doesn't have enough pages for the allocation new pages are
         * allocated from outside of pool.
         */
        if (pool->fill_lock)
                return;

        pool->fill_lock = true;

        /* If allocation request is small and there are not enough
         * pages in a pool we fill the pool up first. */
        if (count < _manager->options.small
                && count > pool->npages) {
                struct pglist new_pages;
                unsigned alloc_size = _manager->options.alloc_size;

                /**
                 * Can't change page caching if in irqsave context. We have to
                 * drop the pool->lock.
                 */
                mtx_unlock(&pool->lock);

                TAILQ_INIT(&new_pages);
                r = ttm_alloc_new_pages(&new_pages, pool->ttm_page_alloc_flags,
                    ttm_flags, cstate, alloc_size);
                mtx_lock(&pool->lock);

                if (!r) {
                        TAILQ_CONCAT(&pool->list, &new_pages, plinks.q);
                        ++pool->nrefills;
                        pool->npages += alloc_size;
                } else {
                        printf("[TTM] Failed to fill pool (%p)\n", pool);
                        /* If we have any pages left put them to the pool. */
                        TAILQ_FOREACH(p, &pool->list, plinks.q) {
                                ++cpages;
                        }
                        TAILQ_CONCAT(&pool->list, &new_pages, plinks.q);
                        pool->npages += cpages;
                }

        }
        pool->fill_lock = false;
}

/**
 * Cut 'count' number of pages from the pool and put them on the return list.
 *
 * @return count of pages still required to fulfill the request.
 */
static unsigned ttm_page_pool_get_pages(struct ttm_page_pool *pool,
                                        struct pglist *pages,
                                        int ttm_flags,
                                        enum ttm_caching_state cstate,
                                        unsigned count)
{
        vm_page_t p;
        unsigned i;

        mtx_lock(&pool->lock);
        ttm_page_pool_fill_locked(pool, ttm_flags, cstate, count);

        if (count >= pool->npages) {
                /* take all pages from the pool */
                TAILQ_CONCAT(pages, &pool->list, plinks.q);
                count -= pool->npages;
                pool->npages = 0;
                goto out;
        }
        for (i = 0; i < count; i++) {
                p = TAILQ_FIRST(&pool->list);
                TAILQ_REMOVE(&pool->list, p, plinks.q);
                TAILQ_INSERT_TAIL(pages, p, plinks.q);
        }
        pool->npages -= count;
        count = 0;
out:
        mtx_unlock(&pool->lock);
        return count;
}

/* Put all pages in pages list to correct pool to wait for reuse */
static void ttm_put_pages(vm_page_t *pages, unsigned npages, int flags,
                          enum ttm_caching_state cstate)
{
        struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
        unsigned i;

        if (pool == NULL) {
                /* No pool for this memory type so free the pages */
                for (i = 0; i < npages; i++) {
                        if (pages[i]) {
                                ttm_vm_page_free(pages[i]);
                                pages[i] = NULL;
                        }
                }
                return;
        }

        mtx_lock(&pool->lock);
        for (i = 0; i < npages; i++) {
                if (pages[i]) {
                        TAILQ_INSERT_TAIL(&pool->list, pages[i], plinks.q);
                        pages[i] = NULL;
                        pool->npages++;
                }
        }
        /* Check that we don't go over the pool limit */
        npages = 0;
        if (pool->npages > _manager->options.max_size) {
                npages = pool->npages - _manager->options.max_size;
                /* free at least NUM_PAGES_TO_ALLOC number of pages
                 * to reduce calls to set_memory_wb */
                if (npages < NUM_PAGES_TO_ALLOC)
                        npages = NUM_PAGES_TO_ALLOC;
        }
        mtx_unlock(&pool->lock);
        if (npages)
                ttm_page_pool_free(pool, npages);
}

/*
 * On success pages list will hold count number of correctly
 * cached pages.
 */
static int ttm_get_pages(vm_page_t *pages, unsigned npages, int flags,
                         enum ttm_caching_state cstate)
{
        struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
        struct pglist plist;
        vm_page_t p = NULL;
        int gfp_flags;
        unsigned count;
        int r;

        /* No pool for cached pages */
        if (pool == NULL) {
                for (r = 0; r < npages; ++r) {
                        p = ttm_vm_page_alloc(flags, cstate);
                        if (!p) {
                                printf("[TTM] Unable to allocate page\n");
                                return -ENOMEM;
                        }
                        pages[r] = p;
                }
                return 0;
        }

        /* combine zero flag to pool flags */
        gfp_flags = flags | pool->ttm_page_alloc_flags;

        /* First we take pages from the pool */
        TAILQ_INIT(&plist);
        npages = ttm_page_pool_get_pages(pool, &plist, flags, cstate, npages);
        count = 0;
        TAILQ_FOREACH(p, &plist, plinks.q) {
                pages[count++] = p;
        }

        /* clear the pages coming from the pool if requested */
        if (flags & TTM_PAGE_FLAG_ZERO_ALLOC) {
                TAILQ_FOREACH(p, &plist, plinks.q) {
                        pmap_zero_page(p);
                }
        }

        /* If pool didn't have enough pages allocate new one. */
        if (npages > 0) {
                /* ttm_alloc_new_pages doesn't reference pool so we can run
                 * multiple requests in parallel.
                 **/
                TAILQ_INIT(&plist);
                r = ttm_alloc_new_pages(&plist, gfp_flags, flags, cstate,
                    npages);
                TAILQ_FOREACH(p, &plist, plinks.q) {
                        pages[count++] = p;
                }
                if (r) {
                        /* If there is any pages in the list put them back to
                         * the pool. */
                        printf("[TTM] Failed to allocate extra pages for large request\n");
                        ttm_put_pages(pages, count, flags, cstate);
                        return r;
                }
        }

        return 0;
}

static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, int flags,
                                      char *name)
{
        mtx_init(&pool->lock, "ttmpool", NULL, MTX_DEF);
        pool->fill_lock = false;
        TAILQ_INIT(&pool->list);
        pool->npages = pool->nfrees = 0;
        pool->ttm_page_alloc_flags = flags;
        pool->name = name;
}

int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
{

        if (_manager != NULL)
                printf("[TTM] manager != NULL\n");
        printf("[TTM] Initializing pool allocator\n");

        _manager = malloc(sizeof(*_manager), M_TTM_POOLMGR, M_WAITOK | M_ZERO);

        ttm_page_pool_init_locked(&_manager->wc_pool, 0, "wc");
        ttm_page_pool_init_locked(&_manager->uc_pool, 0, "uc");
        ttm_page_pool_init_locked(&_manager->wc_pool_dma32,
            TTM_PAGE_FLAG_DMA32, "wc dma");
        ttm_page_pool_init_locked(&_manager->uc_pool_dma32,
            TTM_PAGE_FLAG_DMA32, "uc dma");

        _manager->options.max_size = max_pages;
        _manager->options.small = SMALL_ALLOCATION;
        _manager->options.alloc_size = NUM_PAGES_TO_ALLOC;

        refcount_init(&_manager->kobj_ref, 1);
        ttm_pool_mm_shrink_init(_manager);

        return 0;
}

void ttm_page_alloc_fini(void)
{
        int i;

        printf("[TTM] Finalizing pool allocator\n");
        ttm_pool_mm_shrink_fini(_manager);

        for (i = 0; i < NUM_POOLS; ++i)
                ttm_page_pool_free(&_manager->pools[i], FREE_ALL_PAGES);

        if (refcount_release(&_manager->kobj_ref))
                ttm_pool_kobj_release(_manager);
        _manager = NULL;
}

int ttm_pool_populate(struct ttm_tt *ttm)
{
        struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
        unsigned i;
        int ret;

        if (ttm->state != tt_unpopulated)
                return 0;

        for (i = 0; i < ttm->num_pages; ++i) {
                ret = ttm_get_pages(&ttm->pages[i], 1,
                                    ttm->page_flags,
                                    ttm->caching_state);
                if (ret != 0) {
                        ttm_pool_unpopulate(ttm);
                        return -ENOMEM;
                }

                ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
                                                false, false);
                if (unlikely(ret != 0)) {
                        ttm_pool_unpopulate(ttm);
                        return -ENOMEM;
                }
        }

        if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
                ret = ttm_tt_swapin(ttm);
                if (unlikely(ret != 0)) {
                        ttm_pool_unpopulate(ttm);
                        return ret;
                }
        }

        ttm->state = tt_unbound;
        return 0;
}

void ttm_pool_unpopulate(struct ttm_tt *ttm)
{
        unsigned i;

        for (i = 0; i < ttm->num_pages; ++i) {
                if (ttm->pages[i]) {
                        ttm_mem_global_free_page(ttm->glob->mem_glob,
                                                 ttm->pages[i]);
                        ttm_put_pages(&ttm->pages[i], 1,
                                      ttm->page_flags,
                                      ttm->caching_state);
                }
        }
        ttm->state = tt_unpopulated;
}

#if 0
/* XXXKIB sysctl */
int ttm_page_alloc_debugfs(struct seq_file *m, void *data)
{
        struct ttm_page_pool *p;
        unsigned i;
        char *h[] = {"pool", "refills", "pages freed", "size"};
        if (!_manager) {
                seq_printf(m, "No pool allocator running.\n");
                return 0;
        }
        seq_printf(m, "%6s %12s %13s %8s\n",
                        h[0], h[1], h[2], h[3]);
        for (i = 0; i < NUM_POOLS; ++i) {
                p = &_manager->pools[i];

                seq_printf(m, "%6s %12ld %13ld %8d\n",
                                p->name, p->nrefills,
                                p->nfrees, p->npages);
        }
        return 0;
}
#endif