drivers/gpu/drm/i915/i915_gem_shrinker.c

   1 /*
   2  * Copyright © 2008-2015 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  */
  24
  25 #include <linux/oom.h>
  26 #include <linux/shmem_fs.h>
  27 #include <linux/slab.h>
  28 #include <linux/swap.h>
  29 #include <linux/pci.h>
  30 #include <linux/dma-buf.h>
  31 #include <linux/vmalloc.h>
  32 #include <drm/drmP.h>
  33 #include <drm/i915_drm.h>
  34
  35 #include "i915_drv.h"
  36 #include "i915_trace.h"
  37
  38 static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
  39 {
  40         switch (mutex_trylock_recursive(&dev->struct_mutex)) {
  41         case MUTEX_TRYLOCK_FAILED:
  42                 return false;
  43
  44         case MUTEX_TRYLOCK_SUCCESS:
  45                 *unlock = true;
  46                 return true;
  47
  48         case MUTEX_TRYLOCK_RECURSIVE:
  49                 *unlock = false;
  50                 return true;
  51         }
  52
  53         BUG();
  54 }
  55
  56 static void i915_gem_shrinker_unlock(struct drm_device *dev, bool unlock)
  57 {
  58         if (!unlock)
  59                 return;
  60
  61         mutex_unlock(&dev->struct_mutex);
  62 }
  63
  64 static bool any_vma_pinned(struct drm_i915_gem_object *obj)
  65 {
  66         struct i915_vma *vma;
  67
  68         list_for_each_entry(vma, &obj->vma_list, obj_link)
  69                 if (i915_vma_is_pinned(vma))
  70                         return true;
  71
  72         return false;
  73 }
  74
  75 static bool swap_available(void)
  76 {
  77         return get_nr_swap_pages() > 0;
  78 }
  79
  80 static bool can_release_pages(struct drm_i915_gem_object *obj)
  81 {
  82         if (!obj->mm.pages)
  83                 return false;
  84
  85         /* Consider only shrinkable ojects. */
  86         if (!i915_gem_object_is_shrinkable(obj))
  87                 return false;
  88
  89         /* Only report true if by unbinding the object and putting its pages
  90          * we can actually make forward progress towards freeing physical
  91          * pages.
  92          *
  93          * If the pages are pinned for any other reason than being bound
  94          * to the GPU, simply unbinding from the GPU is not going to succeed
  95          * in releasing our pin count on the pages themselves.
  96          */
  97         if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count)
  98                 return false;
  99
 100         if (any_vma_pinned(obj))
 101                 return false;
 102
 103         /* We can only return physical pages to the system if we can either
 104          * discard the contents (because the user has marked them as being
 105          * purgeable) or if we can move their contents out to swap.
 106          */
 107         return swap_available() || obj->mm.madv == I915_MADV_DONTNEED;
 108 }
 109
 110 static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
 111 {
 112         if (i915_gem_object_unbind(obj) == 0)
 113                 __i915_gem_object_put_pages(obj, I915_MM_SHRINKER);
 114         return !READ_ONCE(obj->mm.pages);
 115 }
 116
 117 /**
 118  * i915_gem_shrink - Shrink buffer object caches
 119  * @dev_priv: i915 device
 120  * @target: amount of memory to make available, in pages
 121  * @flags: control flags for selecting cache types
 122  *
 123  * This function is the main interface to the shrinker. It will try to release
 124  * up to @target pages of main memory backing storage from buffer objects.
 125  * Selection of the specific caches can be done with @flags. This is e.g. useful
 126  * when purgeable objects should be removed from caches preferentially.
 127  *
 128  * Note that it's not guaranteed that released amount is actually available as
 129  * free system memory - the pages might still be in-used to due to other reasons
 130  * (like cpu mmaps) or the mm core has reused them before we could grab them.
 131  * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
 132  * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
 133  *
 134  * Also note that any kind of pinning (both per-vma address space pins and
 135  * backing storage pins at the buffer object level) result in the shrinker code
 136  * having to skip the object.
 137  *
 138  * Returns:
 139  * The number of pages of backing storage actually released.
 140  */
 141 unsigned long
 142 i915_gem_shrink(struct drm_i915_private *dev_priv,
 143                 unsigned long target, unsigned flags)
 144 {
 145         const struct {
 146                 struct list_head *list;
 147                 unsigned int bit;
 148         } phases[] = {
 149                 { &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
 150                 { &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
 151                 { NULL, 0 },
 152         }, *phase;
 153         unsigned long count = 0;
 154         bool unlock;
 155
 156         if (!i915_gem_shrinker_lock(&dev_priv->drm, &unlock))
 157                 return 0;
 158
 159         trace_i915_gem_shrink(dev_priv, target, flags);
 160         i915_gem_retire_requests(dev_priv);
 161
 162         /*
 163          * Unbinding of objects will require HW access; Let us not wake the
 164          * device just to recover a little memory. If absolutely necessary,
 165          * we will force the wake during oom-notifier.
 166          */
 167         if ((flags & I915_SHRINK_BOUND) &&
 168             !intel_runtime_pm_get_if_in_use(dev_priv))
 169                 flags &= ~I915_SHRINK_BOUND;
 170
 171         /*
 172          * As we may completely rewrite the (un)bound list whilst unbinding
 173          * (due to retiring requests) we have to strictly process only
 174          * one element of the list at the time, and recheck the list
 175          * on every iteration.
 176          *
 177          * In particular, we must hold a reference whilst removing the
 178          * object as we may end up waiting for and/or retiring the objects.
 179          * This might release the final reference (held by the active list)
 180          * and result in the object being freed from under us. This is
 181          * similar to the precautions the eviction code must take whilst
 182          * removing objects.
 183          *
 184          * Also note that although these lists do not hold a reference to
 185          * the object we can safely grab one here: The final object
 186          * unreferencing and the bound_list are both protected by the
 187          * dev->struct_mutex and so we won't ever be able to observe an
 188          * object on the bound_list with a reference count equals 0.
 189          */
 190         for (phase = phases; phase->list; phase++) {
 191                 struct list_head still_in_list;
 192                 struct drm_i915_gem_object *obj;
 193
 194                 if ((flags & phase->bit) == 0)
 195                         continue;
 196
 197                 INIT_LIST_HEAD(&still_in_list);
 198                 while (count < target &&
 199                        (obj = list_first_entry_or_null(phase->list,
 200                                                        typeof(*obj),
 201                                                        global_link))) {
 202                         list_move_tail(&obj->global_link, &still_in_list);
 203                         if (!obj->mm.pages) {
 204                                 list_del_init(&obj->global_link);
 205                                 continue;
 206                         }
 207
 208                         if (flags & I915_SHRINK_PURGEABLE &&
 209                             obj->mm.madv != I915_MADV_DONTNEED)
 210                                 continue;
 211
 212                         if (flags & I915_SHRINK_VMAPS &&
 213                             !is_vmalloc_addr(obj->mm.mapping))
 214                                 continue;
 215
 216                         if (!(flags & I915_SHRINK_ACTIVE) &&
 217                             (i915_gem_object_is_active(obj) ||
 218                              i915_gem_object_is_framebuffer(obj)))
 219                                 continue;
 220
 221                         if (!can_release_pages(obj))
 222                                 continue;
 223
 224                         if (unsafe_drop_pages(obj)) {
 225                                 /* May arrive from get_pages on another bo */
 226                                 mutex_lock_nested(&obj->mm.lock,
 227                                                   I915_MM_SHRINKER);
 228                                 if (!obj->mm.pages) {
 229                                         __i915_gem_object_invalidate(obj);
 230                                         list_del_init(&obj->global_link);
 231                                         count += obj->base.size >> PAGE_SHIFT;
 232                                 }
 233                                 mutex_unlock(&obj->mm.lock);
 234                         }
 235                 }
 236                 list_splice_tail(&still_in_list, phase->list);
 237         }
 238
 239         if (flags & I915_SHRINK_BOUND)
 240                 intel_runtime_pm_put(dev_priv);
 241
 242         i915_gem_retire_requests(dev_priv);
 243
 244         i915_gem_shrinker_unlock(&dev_priv->drm, unlock);
 245
 246         return count;
 247 }
 248
 249 /**
 250  * i915_gem_shrink_all - Shrink buffer object caches completely
 251  * @dev_priv: i915 device
 252  *
 253  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
 254  * caches completely. It also first waits for and retires all outstanding
 255  * requests to also be able to release backing storage for active objects.
 256  *
 257  * This should only be used in code to intentionally quiescent the gpu or as a
 258  * last-ditch effort when memory seems to have run out.
 259  *
 260  * Returns:
 261  * The number of pages of backing storage actually released.
 262  */
 263 unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 264 {
 265         unsigned long freed;
 266
 267         intel_runtime_pm_get(dev_priv);
 268         freed = i915_gem_shrink(dev_priv, -1UL,
 269                                 I915_SHRINK_BOUND |
 270                                 I915_SHRINK_UNBOUND |
 271                                 I915_SHRINK_ACTIVE);
 272         intel_runtime_pm_put(dev_priv);
 273
 274         return freed;
 275 }
 276
 277 static unsigned long
 278 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 279 {
 280         struct drm_i915_private *dev_priv =
 281                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 282         struct drm_device *dev = &dev_priv->drm;
 283         struct drm_i915_gem_object *obj;
 284         unsigned long count;
 285         bool unlock;
 286
 287         if (!i915_gem_shrinker_lock(dev, &unlock))
 288                 return 0;
 289
 290         i915_gem_retire_requests(dev_priv);
 291
 292         count = 0;
 293         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_link)
 294                 if (can_release_pages(obj))
 295                         count += obj->base.size >> PAGE_SHIFT;
 296
 297         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_link) {
 298                 if (!i915_gem_object_is_active(obj) && can_release_pages(obj))
 299                         count += obj->base.size >> PAGE_SHIFT;
 300         }
 301
 302         i915_gem_shrinker_unlock(dev, unlock);
 303
 304         return count;
 305 }
 306
 307 static unsigned long
 308 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 309 {
 310         struct drm_i915_private *dev_priv =
 311                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 312         struct drm_device *dev = &dev_priv->drm;
 313         unsigned long freed;
 314         bool unlock;
 315
 316         if (!i915_gem_shrinker_lock(dev, &unlock))
 317                 return SHRINK_STOP;
 318
 319         freed = i915_gem_shrink(dev_priv,
 320                                 sc->nr_to_scan,
 321                                 I915_SHRINK_BOUND |
 322                                 I915_SHRINK_UNBOUND |
 323                                 I915_SHRINK_PURGEABLE);
 324         if (freed < sc->nr_to_scan)
 325                 freed += i915_gem_shrink(dev_priv,
 326                                          sc->nr_to_scan - freed,
 327                                          I915_SHRINK_BOUND |
 328                                          I915_SHRINK_UNBOUND);
 329
 330         i915_gem_shrinker_unlock(dev, unlock);
 331
 332         return freed;
 333 }
 334
 335 struct shrinker_lock_uninterruptible {
 336         bool was_interruptible;
 337         bool unlock;
 338 };
 339
 340 static bool
 341 i915_gem_shrinker_lock_uninterruptible(struct drm_i915_private *dev_priv,
 342                                        struct shrinker_lock_uninterruptible *slu,
 343                                        int timeout_ms)
 344 {
 345         unsigned long timeout = jiffies + msecs_to_jiffies_timeout(timeout_ms);
 346
 347         do {
 348                 if (i915_gem_wait_for_idle(dev_priv, 0) == 0 &&
 349                     i915_gem_shrinker_lock(&dev_priv->drm, &slu->unlock))
 350                         break;
 351
 352                 schedule_timeout_killable(1);
 353                 if (fatal_signal_pending(current))
 354                         return false;
 355
 356                 if (time_after(jiffies, timeout)) {
 357                         pr_err("Unable to lock GPU to purge memory.\n");
 358                         return false;
 359                 }
 360         } while (1);
 361
 362         slu->was_interruptible = dev_priv->mm.interruptible;
 363         dev_priv->mm.interruptible = false;
 364         return true;
 365 }
 366
 367 static void
 368 i915_gem_shrinker_unlock_uninterruptible(struct drm_i915_private *dev_priv,
 369                                          struct shrinker_lock_uninterruptible *slu)
 370 {
 371         dev_priv->mm.interruptible = slu->was_interruptible;
 372         i915_gem_shrinker_unlock(&dev_priv->drm, slu->unlock);
 373 }
 374
 375 static int
 376 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 377 {
 378         struct drm_i915_private *dev_priv =
 379                 container_of(nb, struct drm_i915_private, mm.oom_notifier);
 380         struct shrinker_lock_uninterruptible slu;
 381         struct drm_i915_gem_object *obj;
 382         unsigned long unevictable, bound, unbound, freed_pages;
 383
 384         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 385                 return NOTIFY_DONE;
 386
 387         freed_pages = i915_gem_shrink_all(dev_priv);
 388
 389         /* Because we may be allocating inside our own driver, we cannot
 390          * assert that there are no objects with pinned pages that are not
 391          * being pointed to by hardware.
 392          */
 393         unbound = bound = unevictable = 0;
 394         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_link) {
 395                 if (!obj->mm.pages)
 396                         continue;
 397
 398                 if (!can_release_pages(obj))
 399                         unevictable += obj->base.size >> PAGE_SHIFT;
 400                 else
 401                         unbound += obj->base.size >> PAGE_SHIFT;
 402         }
 403         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_link) {
 404                 if (!obj->mm.pages)
 405                         continue;
 406
 407                 if (!can_release_pages(obj))
 408                         unevictable += obj->base.size >> PAGE_SHIFT;
 409                 else
 410                         bound += obj->base.size >> PAGE_SHIFT;
 411         }
 412
 413         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 414
 415         if (freed_pages || unbound || bound)
 416                 pr_info("Purging GPU memory, %lu pages freed, "
 417                         "%lu pages still pinned.\n",
 418                         freed_pages, unevictable);
 419         if (unbound || bound)
 420                 pr_err("%lu and %lu pages still available in the "
 421                        "bound and unbound GPU page lists.\n",
 422                        bound, unbound);
 423
 424         *(unsigned long *)ptr += freed_pages;
 425         return NOTIFY_DONE;
 426 }
 427
 428 static int
 429 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
 430 {
 431         struct drm_i915_private *dev_priv =
 432                 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
 433         struct shrinker_lock_uninterruptible slu;
 434         struct i915_vma *vma, *next;
 435         unsigned long freed_pages = 0;
 436         int ret;
 437
 438         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 439                 return NOTIFY_DONE;
 440
 441         /* Force everything onto the inactive lists */
 442         ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED);
 443         if (ret)
 444                 goto out;
 445
 446         intel_runtime_pm_get(dev_priv);
 447         freed_pages += i915_gem_shrink(dev_priv, -1UL,
 448                                        I915_SHRINK_BOUND |
 449                                        I915_SHRINK_UNBOUND |
 450                                        I915_SHRINK_ACTIVE |
 451                                        I915_SHRINK_VMAPS);
 452         intel_runtime_pm_put(dev_priv);
 453
 454         /* We also want to clear any cached iomaps as they wrap vmap */
 455         list_for_each_entry_safe(vma, next,
 456                                  &dev_priv->ggtt.base.inactive_list, vm_link) {
 457                 unsigned long count = vma->node.size >> PAGE_SHIFT;
 458                 if (vma->iomap && i915_vma_unbind(vma) == 0)
 459                         freed_pages += count;
 460         }
 461
 462 out:
 463         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 464
 465         *(unsigned long *)ptr += freed_pages;
 466         return NOTIFY_DONE;
 467 }
 468
 469 /**
 470  * i915_gem_shrinker_init - Initialize i915 shrinker
 471  * @dev_priv: i915 device
 472  *
 473  * This function registers and sets up the i915 shrinker and OOM handler.
 474  */
 475 void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
 476 {
 477         dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
 478         dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
 479         dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
 480         WARN_ON(register_shrinker(&dev_priv->mm.shrinker));
 481
 482         dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 483         WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));
 484
 485         dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
 486         WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 487 }
 488
 489 /**
 490  * i915_gem_shrinker_cleanup - Clean up i915 shrinker
 491  * @dev_priv: i915 device
 492  *
 493  * This function unregisters the i915 shrinker and OOM handler.
 494  */
 495 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
 496 {
 497         WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 498         WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 499         unregister_shrinker(&dev_priv->mm.shrinker);
 500 }