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