linux/drivers/gpu/drm/ttm/ttm_memory.c
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   1/* SPDX-License-Identifier: GPL-2.0 OR MIT */
   2/**************************************************************************
   3 *
   4 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   5 * All Rights Reserved.
   6 *
   7 * Permission is hereby granted, free of charge, to any person obtaining a
   8 * copy of this software and associated documentation files (the
   9 * "Software"), to deal in the Software without restriction, including
  10 * without limitation the rights to use, copy, modify, merge, publish,
  11 * distribute, sub license, and/or sell copies of the Software, and to
  12 * permit persons to whom the Software is furnished to do so, subject to
  13 * the following conditions:
  14 *
  15 * The above copyright notice and this permission notice (including the
  16 * next paragraph) shall be included in all copies or substantial portions
  17 * of the Software.
  18 *
  19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  22 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  23 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  24 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  25 * USE OR OTHER DEALINGS IN THE SOFTWARE.
  26 *
  27 **************************************************************************/
  28
  29#define pr_fmt(fmt) "[TTM] " fmt
  30
  31#include <drm/ttm/ttm_memory.h>
  32#include <drm/ttm/ttm_module.h>
  33#include <drm/ttm/ttm_page_alloc.h>
  34#include <linux/spinlock.h>
  35#include <linux/sched.h>
  36#include <linux/wait.h>
  37#include <linux/mm.h>
  38#include <linux/module.h>
  39#include <linux/slab.h>
  40#include <linux/swap.h>
  41
  42#define TTM_MEMORY_ALLOC_RETRIES 4
  43
  44struct ttm_mem_global ttm_mem_glob;
  45EXPORT_SYMBOL(ttm_mem_glob);
  46
  47struct ttm_mem_zone {
  48        struct kobject kobj;
  49        struct ttm_mem_global *glob;
  50        const char *name;
  51        uint64_t zone_mem;
  52        uint64_t emer_mem;
  53        uint64_t max_mem;
  54        uint64_t swap_limit;
  55        uint64_t used_mem;
  56};
  57
  58static struct attribute ttm_mem_sys = {
  59        .name = "zone_memory",
  60        .mode = S_IRUGO
  61};
  62static struct attribute ttm_mem_emer = {
  63        .name = "emergency_memory",
  64        .mode = S_IRUGO | S_IWUSR
  65};
  66static struct attribute ttm_mem_max = {
  67        .name = "available_memory",
  68        .mode = S_IRUGO | S_IWUSR
  69};
  70static struct attribute ttm_mem_swap = {
  71        .name = "swap_limit",
  72        .mode = S_IRUGO | S_IWUSR
  73};
  74static struct attribute ttm_mem_used = {
  75        .name = "used_memory",
  76        .mode = S_IRUGO
  77};
  78
  79static void ttm_mem_zone_kobj_release(struct kobject *kobj)
  80{
  81        struct ttm_mem_zone *zone =
  82                container_of(kobj, struct ttm_mem_zone, kobj);
  83
  84        pr_info("Zone %7s: Used memory at exit: %llu KiB\n",
  85                zone->name, (unsigned long long)zone->used_mem >> 10);
  86        kfree(zone);
  87}
  88
  89static ssize_t ttm_mem_zone_show(struct kobject *kobj,
  90                                 struct attribute *attr,
  91                                 char *buffer)
  92{
  93        struct ttm_mem_zone *zone =
  94                container_of(kobj, struct ttm_mem_zone, kobj);
  95        uint64_t val = 0;
  96
  97        spin_lock(&zone->glob->lock);
  98        if (attr == &ttm_mem_sys)
  99                val = zone->zone_mem;
 100        else if (attr == &ttm_mem_emer)
 101                val = zone->emer_mem;
 102        else if (attr == &ttm_mem_max)
 103                val = zone->max_mem;
 104        else if (attr == &ttm_mem_swap)
 105                val = zone->swap_limit;
 106        else if (attr == &ttm_mem_used)
 107                val = zone->used_mem;
 108        spin_unlock(&zone->glob->lock);
 109
 110        return snprintf(buffer, PAGE_SIZE, "%llu\n",
 111                        (unsigned long long) val >> 10);
 112}
 113
 114static void ttm_check_swapping(struct ttm_mem_global *glob);
 115
 116static ssize_t ttm_mem_zone_store(struct kobject *kobj,
 117                                  struct attribute *attr,
 118                                  const char *buffer,
 119                                  size_t size)
 120{
 121        struct ttm_mem_zone *zone =
 122                container_of(kobj, struct ttm_mem_zone, kobj);
 123        int chars;
 124        unsigned long val;
 125        uint64_t val64;
 126
 127        chars = sscanf(buffer, "%lu", &val);
 128        if (chars == 0)
 129                return size;
 130
 131        val64 = val;
 132        val64 <<= 10;
 133
 134        spin_lock(&zone->glob->lock);
 135        if (val64 > zone->zone_mem)
 136                val64 = zone->zone_mem;
 137        if (attr == &ttm_mem_emer) {
 138                zone->emer_mem = val64;
 139                if (zone->max_mem > val64)
 140                        zone->max_mem = val64;
 141        } else if (attr == &ttm_mem_max) {
 142                zone->max_mem = val64;
 143                if (zone->emer_mem < val64)
 144                        zone->emer_mem = val64;
 145        } else if (attr == &ttm_mem_swap)
 146                zone->swap_limit = val64;
 147        spin_unlock(&zone->glob->lock);
 148
 149        ttm_check_swapping(zone->glob);
 150
 151        return size;
 152}
 153
 154static struct attribute *ttm_mem_zone_attrs[] = {
 155        &ttm_mem_sys,
 156        &ttm_mem_emer,
 157        &ttm_mem_max,
 158        &ttm_mem_swap,
 159        &ttm_mem_used,
 160        NULL
 161};
 162
 163static const struct sysfs_ops ttm_mem_zone_ops = {
 164        .show = &ttm_mem_zone_show,
 165        .store = &ttm_mem_zone_store
 166};
 167
 168static struct kobj_type ttm_mem_zone_kobj_type = {
 169        .release = &ttm_mem_zone_kobj_release,
 170        .sysfs_ops = &ttm_mem_zone_ops,
 171        .default_attrs = ttm_mem_zone_attrs,
 172};
 173
 174static struct attribute ttm_mem_global_lower_mem_limit = {
 175        .name = "lower_mem_limit",
 176        .mode = S_IRUGO | S_IWUSR
 177};
 178
 179static ssize_t ttm_mem_global_show(struct kobject *kobj,
 180                                 struct attribute *attr,
 181                                 char *buffer)
 182{
 183        struct ttm_mem_global *glob =
 184                container_of(kobj, struct ttm_mem_global, kobj);
 185        uint64_t val = 0;
 186
 187        spin_lock(&glob->lock);
 188        val = glob->lower_mem_limit;
 189        spin_unlock(&glob->lock);
 190        /* convert from number of pages to KB */
 191        val <<= (PAGE_SHIFT - 10);
 192        return snprintf(buffer, PAGE_SIZE, "%llu\n",
 193                        (unsigned long long) val);
 194}
 195
 196static ssize_t ttm_mem_global_store(struct kobject *kobj,
 197                                  struct attribute *attr,
 198                                  const char *buffer,
 199                                  size_t size)
 200{
 201        int chars;
 202        uint64_t val64;
 203        unsigned long val;
 204        struct ttm_mem_global *glob =
 205                container_of(kobj, struct ttm_mem_global, kobj);
 206
 207        chars = sscanf(buffer, "%lu", &val);
 208        if (chars == 0)
 209                return size;
 210
 211        val64 = val;
 212        /* convert from KB to number of pages */
 213        val64 >>= (PAGE_SHIFT - 10);
 214
 215        spin_lock(&glob->lock);
 216        glob->lower_mem_limit = val64;
 217        spin_unlock(&glob->lock);
 218
 219        return size;
 220}
 221
 222static struct attribute *ttm_mem_global_attrs[] = {
 223        &ttm_mem_global_lower_mem_limit,
 224        NULL
 225};
 226
 227static const struct sysfs_ops ttm_mem_global_ops = {
 228        .show = &ttm_mem_global_show,
 229        .store = &ttm_mem_global_store,
 230};
 231
 232static struct kobj_type ttm_mem_glob_kobj_type = {
 233        .sysfs_ops = &ttm_mem_global_ops,
 234        .default_attrs = ttm_mem_global_attrs,
 235};
 236
 237static bool ttm_zones_above_swap_target(struct ttm_mem_global *glob,
 238                                        bool from_wq, uint64_t extra)
 239{
 240        unsigned int i;
 241        struct ttm_mem_zone *zone;
 242        uint64_t target;
 243
 244        for (i = 0; i < glob->num_zones; ++i) {
 245                zone = glob->zones[i];
 246
 247                if (from_wq)
 248                        target = zone->swap_limit;
 249                else if (capable(CAP_SYS_ADMIN))
 250                        target = zone->emer_mem;
 251                else
 252                        target = zone->max_mem;
 253
 254                target = (extra > target) ? 0ULL : target;
 255
 256                if (zone->used_mem > target)
 257                        return true;
 258        }
 259        return false;
 260}
 261
 262/**
 263 * At this point we only support a single shrink callback.
 264 * Extend this if needed, perhaps using a linked list of callbacks.
 265 * Note that this function is reentrant:
 266 * many threads may try to swap out at any given time.
 267 */
 268
 269static void ttm_shrink(struct ttm_mem_global *glob, bool from_wq,
 270                        uint64_t extra, struct ttm_operation_ctx *ctx)
 271{
 272        int ret;
 273
 274        spin_lock(&glob->lock);
 275
 276        while (ttm_zones_above_swap_target(glob, from_wq, extra)) {
 277                spin_unlock(&glob->lock);
 278                ret = ttm_bo_swapout(&ttm_bo_glob, ctx);
 279                spin_lock(&glob->lock);
 280                if (unlikely(ret != 0))
 281                        break;
 282        }
 283
 284        spin_unlock(&glob->lock);
 285}
 286
 287static void ttm_shrink_work(struct work_struct *work)
 288{
 289        struct ttm_operation_ctx ctx = {
 290                .interruptible = false,
 291                .no_wait_gpu = false
 292        };
 293        struct ttm_mem_global *glob =
 294            container_of(work, struct ttm_mem_global, work);
 295
 296        ttm_shrink(glob, true, 0ULL, &ctx);
 297}
 298
 299static int ttm_mem_init_kernel_zone(struct ttm_mem_global *glob,
 300                                    const struct sysinfo *si)
 301{
 302        struct ttm_mem_zone *zone = kzalloc(sizeof(*zone), GFP_KERNEL);
 303        uint64_t mem;
 304        int ret;
 305
 306        if (unlikely(!zone))
 307                return -ENOMEM;
 308
 309        mem = si->totalram - si->totalhigh;
 310        mem *= si->mem_unit;
 311
 312        zone->name = "kernel";
 313        zone->zone_mem = mem;
 314        zone->max_mem = mem >> 1;
 315        zone->emer_mem = (mem >> 1) + (mem >> 2);
 316        zone->swap_limit = zone->max_mem - (mem >> 3);
 317        zone->used_mem = 0;
 318        zone->glob = glob;
 319        glob->zone_kernel = zone;
 320        ret = kobject_init_and_add(
 321                &zone->kobj, &ttm_mem_zone_kobj_type, &glob->kobj, zone->name);
 322        if (unlikely(ret != 0)) {
 323                kobject_put(&zone->kobj);
 324                return ret;
 325        }
 326        glob->zones[glob->num_zones++] = zone;
 327        return 0;
 328}
 329
 330#ifdef CONFIG_HIGHMEM
 331static int ttm_mem_init_highmem_zone(struct ttm_mem_global *glob,
 332                                     const struct sysinfo *si)
 333{
 334        struct ttm_mem_zone *zone;
 335        uint64_t mem;
 336        int ret;
 337
 338        if (si->totalhigh == 0)
 339                return 0;
 340
 341        zone = kzalloc(sizeof(*zone), GFP_KERNEL);
 342        if (unlikely(!zone))
 343                return -ENOMEM;
 344
 345        mem = si->totalram;
 346        mem *= si->mem_unit;
 347
 348        zone->name = "highmem";
 349        zone->zone_mem = mem;
 350        zone->max_mem = mem >> 1;
 351        zone->emer_mem = (mem >> 1) + (mem >> 2);
 352        zone->swap_limit = zone->max_mem - (mem >> 3);
 353        zone->used_mem = 0;
 354        zone->glob = glob;
 355        glob->zone_highmem = zone;
 356        ret = kobject_init_and_add(
 357                &zone->kobj, &ttm_mem_zone_kobj_type, &glob->kobj, "%s",
 358                zone->name);
 359        if (unlikely(ret != 0)) {
 360                kobject_put(&zone->kobj);
 361                return ret;
 362        }
 363        glob->zones[glob->num_zones++] = zone;
 364        return 0;
 365}
 366#else
 367static int ttm_mem_init_dma32_zone(struct ttm_mem_global *glob,
 368                                   const struct sysinfo *si)
 369{
 370        struct ttm_mem_zone *zone = kzalloc(sizeof(*zone), GFP_KERNEL);
 371        uint64_t mem;
 372        int ret;
 373
 374        if (unlikely(!zone))
 375                return -ENOMEM;
 376
 377        mem = si->totalram;
 378        mem *= si->mem_unit;
 379
 380        /**
 381         * No special dma32 zone needed.
 382         */
 383
 384        if (mem <= ((uint64_t) 1ULL << 32)) {
 385                kfree(zone);
 386                return 0;
 387        }
 388
 389        /*
 390         * Limit max dma32 memory to 4GB for now
 391         * until we can figure out how big this
 392         * zone really is.
 393         */
 394
 395        mem = ((uint64_t) 1ULL << 32);
 396        zone->name = "dma32";
 397        zone->zone_mem = mem;
 398        zone->max_mem = mem >> 1;
 399        zone->emer_mem = (mem >> 1) + (mem >> 2);
 400        zone->swap_limit = zone->max_mem - (mem >> 3);
 401        zone->used_mem = 0;
 402        zone->glob = glob;
 403        glob->zone_dma32 = zone;
 404        ret = kobject_init_and_add(
 405                &zone->kobj, &ttm_mem_zone_kobj_type, &glob->kobj, zone->name);
 406        if (unlikely(ret != 0)) {
 407                kobject_put(&zone->kobj);
 408                return ret;
 409        }
 410        glob->zones[glob->num_zones++] = zone;
 411        return 0;
 412}
 413#endif
 414
 415int ttm_mem_global_init(struct ttm_mem_global *glob)
 416{
 417        struct sysinfo si;
 418        int ret;
 419        int i;
 420        struct ttm_mem_zone *zone;
 421
 422        spin_lock_init(&glob->lock);
 423        glob->swap_queue = create_singlethread_workqueue("ttm_swap");
 424        INIT_WORK(&glob->work, ttm_shrink_work);
 425        ret = kobject_init_and_add(
 426                &glob->kobj, &ttm_mem_glob_kobj_type, ttm_get_kobj(), "memory_accounting");
 427        if (unlikely(ret != 0)) {
 428                kobject_put(&glob->kobj);
 429                return ret;
 430        }
 431
 432        si_meminfo(&si);
 433
 434        /* set it as 0 by default to keep original behavior of OOM */
 435        glob->lower_mem_limit = 0;
 436
 437        ret = ttm_mem_init_kernel_zone(glob, &si);
 438        if (unlikely(ret != 0))
 439                goto out_no_zone;
 440#ifdef CONFIG_HIGHMEM
 441        ret = ttm_mem_init_highmem_zone(glob, &si);
 442        if (unlikely(ret != 0))
 443                goto out_no_zone;
 444#else
 445        ret = ttm_mem_init_dma32_zone(glob, &si);
 446        if (unlikely(ret != 0))
 447                goto out_no_zone;
 448#endif
 449        for (i = 0; i < glob->num_zones; ++i) {
 450                zone = glob->zones[i];
 451                pr_info("Zone %7s: Available graphics memory: %llu KiB\n",
 452                        zone->name, (unsigned long long)zone->max_mem >> 10);
 453        }
 454        ttm_page_alloc_init(glob, glob->zone_kernel->max_mem/(2*PAGE_SIZE));
 455        ttm_dma_page_alloc_init(glob, glob->zone_kernel->max_mem/(2*PAGE_SIZE));
 456        return 0;
 457out_no_zone:
 458        ttm_mem_global_release(glob);
 459        return ret;
 460}
 461
 462void ttm_mem_global_release(struct ttm_mem_global *glob)
 463{
 464        struct ttm_mem_zone *zone;
 465        unsigned int i;
 466
 467        /* let the page allocator first stop the shrink work. */
 468        ttm_page_alloc_fini();
 469        ttm_dma_page_alloc_fini();
 470
 471        flush_workqueue(glob->swap_queue);
 472        destroy_workqueue(glob->swap_queue);
 473        glob->swap_queue = NULL;
 474        for (i = 0; i < glob->num_zones; ++i) {
 475                zone = glob->zones[i];
 476                kobject_del(&zone->kobj);
 477                kobject_put(&zone->kobj);
 478        }
 479        kobject_del(&glob->kobj);
 480        kobject_put(&glob->kobj);
 481        memset(glob, 0, sizeof(*glob));
 482}
 483
 484static void ttm_check_swapping(struct ttm_mem_global *glob)
 485{
 486        bool needs_swapping = false;
 487        unsigned int i;
 488        struct ttm_mem_zone *zone;
 489
 490        spin_lock(&glob->lock);
 491        for (i = 0; i < glob->num_zones; ++i) {
 492                zone = glob->zones[i];
 493                if (zone->used_mem > zone->swap_limit) {
 494                        needs_swapping = true;
 495                        break;
 496                }
 497        }
 498
 499        spin_unlock(&glob->lock);
 500
 501        if (unlikely(needs_swapping))
 502                (void)queue_work(glob->swap_queue, &glob->work);
 503
 504}
 505
 506static void ttm_mem_global_free_zone(struct ttm_mem_global *glob,
 507                                     struct ttm_mem_zone *single_zone,
 508                                     uint64_t amount)
 509{
 510        unsigned int i;
 511        struct ttm_mem_zone *zone;
 512
 513        spin_lock(&glob->lock);
 514        for (i = 0; i < glob->num_zones; ++i) {
 515                zone = glob->zones[i];
 516                if (single_zone && zone != single_zone)
 517                        continue;
 518                zone->used_mem -= amount;
 519        }
 520        spin_unlock(&glob->lock);
 521}
 522
 523void ttm_mem_global_free(struct ttm_mem_global *glob,
 524                         uint64_t amount)
 525{
 526        return ttm_mem_global_free_zone(glob, glob->zone_kernel, amount);
 527}
 528EXPORT_SYMBOL(ttm_mem_global_free);
 529
 530/*
 531 * check if the available mem is under lower memory limit
 532 *
 533 * a. if no swap disk at all or free swap space is under swap_mem_limit
 534 * but available system mem is bigger than sys_mem_limit, allow TTM
 535 * allocation;
 536 *
 537 * b. if the available system mem is less than sys_mem_limit but free
 538 * swap disk is bigger than swap_mem_limit, allow TTM allocation.
 539 */
 540bool
 541ttm_check_under_lowerlimit(struct ttm_mem_global *glob,
 542                        uint64_t num_pages,
 543                        struct ttm_operation_ctx *ctx)
 544{
 545        int64_t available;
 546
 547        if (ctx->flags & TTM_OPT_FLAG_FORCE_ALLOC)
 548                return false;
 549
 550        available = get_nr_swap_pages() + si_mem_available();
 551        available -= num_pages;
 552        if (available < glob->lower_mem_limit)
 553                return true;
 554
 555        return false;
 556}
 557EXPORT_SYMBOL(ttm_check_under_lowerlimit);
 558
 559static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
 560                                  struct ttm_mem_zone *single_zone,
 561                                  uint64_t amount, bool reserve)
 562{
 563        uint64_t limit;
 564        int ret = -ENOMEM;
 565        unsigned int i;
 566        struct ttm_mem_zone *zone;
 567
 568        spin_lock(&glob->lock);
 569        for (i = 0; i < glob->num_zones; ++i) {
 570                zone = glob->zones[i];
 571                if (single_zone && zone != single_zone)
 572                        continue;
 573
 574                limit = (capable(CAP_SYS_ADMIN)) ?
 575                        zone->emer_mem : zone->max_mem;
 576
 577                if (zone->used_mem > limit)
 578                        goto out_unlock;
 579        }
 580
 581        if (reserve) {
 582                for (i = 0; i < glob->num_zones; ++i) {
 583                        zone = glob->zones[i];
 584                        if (single_zone && zone != single_zone)
 585                                continue;
 586                        zone->used_mem += amount;
 587                }
 588        }
 589
 590        ret = 0;
 591out_unlock:
 592        spin_unlock(&glob->lock);
 593        ttm_check_swapping(glob);
 594
 595        return ret;
 596}
 597
 598
 599static int ttm_mem_global_alloc_zone(struct ttm_mem_global *glob,
 600                                     struct ttm_mem_zone *single_zone,
 601                                     uint64_t memory,
 602                                     struct ttm_operation_ctx *ctx)
 603{
 604        int count = TTM_MEMORY_ALLOC_RETRIES;
 605
 606        while (unlikely(ttm_mem_global_reserve(glob,
 607                                               single_zone,
 608                                               memory, true)
 609                        != 0)) {
 610                if (ctx->no_wait_gpu)
 611                        return -ENOMEM;
 612                if (unlikely(count-- == 0))
 613                        return -ENOMEM;
 614                ttm_shrink(glob, false, memory + (memory >> 2) + 16, ctx);
 615        }
 616
 617        return 0;
 618}
 619
 620int ttm_mem_global_alloc(struct ttm_mem_global *glob, uint64_t memory,
 621                         struct ttm_operation_ctx *ctx)
 622{
 623        /**
 624         * Normal allocations of kernel memory are registered in
 625         * the kernel zone.
 626         */
 627
 628        return ttm_mem_global_alloc_zone(glob, glob->zone_kernel, memory, ctx);
 629}
 630EXPORT_SYMBOL(ttm_mem_global_alloc);
 631
 632int ttm_mem_global_alloc_page(struct ttm_mem_global *glob,
 633                              struct page *page, uint64_t size,
 634                              struct ttm_operation_ctx *ctx)
 635{
 636        struct ttm_mem_zone *zone = NULL;
 637
 638        /**
 639         * Page allocations may be registed in a single zone
 640         * only if highmem or !dma32.
 641         */
 642
 643#ifdef CONFIG_HIGHMEM
 644        if (PageHighMem(page) && glob->zone_highmem != NULL)
 645                zone = glob->zone_highmem;
 646#else
 647        if (glob->zone_dma32 && page_to_pfn(page) > 0x00100000UL)
 648                zone = glob->zone_kernel;
 649#endif
 650        return ttm_mem_global_alloc_zone(glob, zone, size, ctx);
 651}
 652
 653void ttm_mem_global_free_page(struct ttm_mem_global *glob, struct page *page,
 654                              uint64_t size)
 655{
 656        struct ttm_mem_zone *zone = NULL;
 657
 658#ifdef CONFIG_HIGHMEM
 659        if (PageHighMem(page) && glob->zone_highmem != NULL)
 660                zone = glob->zone_highmem;
 661#else
 662        if (glob->zone_dma32 && page_to_pfn(page) > 0x00100000UL)
 663                zone = glob->zone_kernel;
 664#endif
 665        ttm_mem_global_free_zone(glob, zone, size);
 666}
 667
 668size_t ttm_round_pot(size_t size)
 669{
 670        if ((size & (size - 1)) == 0)
 671                return size;
 672        else if (size > PAGE_SIZE)
 673                return PAGE_ALIGN(size);
 674        else {
 675                size_t tmp_size = 4;
 676
 677                while (tmp_size < size)
 678                        tmp_size <<= 1;
 679
 680                return tmp_size;
 681        }
 682        return 0;
 683}
 684EXPORT_SYMBOL(ttm_round_pot);
 685
 686uint64_t ttm_get_kernel_zone_memory_size(struct ttm_mem_global *glob)
 687{
 688        return glob->zone_kernel->max_mem;
 689}
 690EXPORT_SYMBOL(ttm_get_kernel_zone_memory_size);
 691