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 mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
  39 {
  40         if (!mutex_is_locked(mutex))
  41                 return false;
  42
  43 #if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER)
  44         return mutex->owner == task;
  45 #else
  46         /* Since UP may be pre-empted, we cannot assume that we own the lock */
  47         return false;
  48 #endif
  49 }
  50
  51 static bool any_vma_pinned(struct drm_i915_gem_object *obj)
  52 {
  53         struct i915_vma *vma;
  54
  55         list_for_each_entry(vma, &obj->vma_list, obj_link)
  56                 if (i915_vma_is_pinned(vma))
  57                         return true;
  58
  59         return false;
  60 }
  61
  62 static bool swap_available(void)
  63 {
  64         return get_nr_swap_pages() > 0;
  65 }
  66
  67 static bool can_release_pages(struct drm_i915_gem_object *obj)
  68 {
  69         /* Only shmemfs objects are backed by swap */
  70         if (!obj->base.filp)
  71                 return false;
  72
  73         /* Only report true if by unbinding the object and putting its pages
  74          * we can actually make forward progress towards freeing physical
  75          * pages.
  76          *
  77          * If the pages are pinned for any other reason than being bound
  78          * to the GPU, simply unbinding from the GPU is not going to succeed
  79          * in releasing our pin count on the pages themselves.
  80          */
  81         if (obj->pages_pin_count > obj->bind_count)
  82                 return false;
  83
  84         if (any_vma_pinned(obj))
  85                 return false;
  86
  87         /* We can only return physical pages to the system if we can either
  88          * discard the contents (because the user has marked them as being
  89          * purgeable) or if we can move their contents out to swap.
  90          */
  91         return swap_available() || obj->madv == I915_MADV_DONTNEED;
  92 }
  93
  94 /**
  95  * i915_gem_shrink - Shrink buffer object caches
  96  * @dev_priv: i915 device
  97  * @target: amount of memory to make available, in pages
  98  * @flags: control flags for selecting cache types
  99  *
 100  * This function is the main interface to the shrinker. It will try to release
 101  * up to @target pages of main memory backing storage from buffer objects.
 102  * Selection of the specific caches can be done with @flags. This is e.g. useful
 103  * when purgeable objects should be removed from caches preferentially.
 104  *
 105  * Note that it's not guaranteed that released amount is actually available as
 106  * free system memory - the pages might still be in-used to due to other reasons
 107  * (like cpu mmaps) or the mm core has reused them before we could grab them.
 108  * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
 109  * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
 110  *
 111  * Also note that any kind of pinning (both per-vma address space pins and
 112  * backing storage pins at the buffer object level) result in the shrinker code
 113  * having to skip the object.
 114  *
 115  * Returns:
 116  * The number of pages of backing storage actually released.
 117  */
 118 unsigned long
 119 i915_gem_shrink(struct drm_i915_private *dev_priv,
 120                 unsigned long target, unsigned flags)
 121 {
 122         const struct {
 123                 struct list_head *list;
 124                 unsigned int bit;
 125         } phases[] = {
 126                 { &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
 127                 { &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
 128                 { NULL, 0 },
 129         }, *phase;
 130         unsigned long count = 0;
 131
 132         trace_i915_gem_shrink(dev_priv, target, flags);
 133         i915_gem_retire_requests(dev_priv);
 134
 135         /*
 136          * Unbinding of objects will require HW access; Let us not wake the
 137          * device just to recover a little memory. If absolutely necessary,
 138          * we will force the wake during oom-notifier.
 139          */
 140         if ((flags & I915_SHRINK_BOUND) &&
 141             !intel_runtime_pm_get_if_in_use(dev_priv))
 142                 flags &= ~I915_SHRINK_BOUND;
 143
 144         /*
 145          * As we may completely rewrite the (un)bound list whilst unbinding
 146          * (due to retiring requests) we have to strictly process only
 147          * one element of the list at the time, and recheck the list
 148          * on every iteration.
 149          *
 150          * In particular, we must hold a reference whilst removing the
 151          * object as we may end up waiting for and/or retiring the objects.
 152          * This might release the final reference (held by the active list)
 153          * and result in the object being freed from under us. This is
 154          * similar to the precautions the eviction code must take whilst
 155          * removing objects.
 156          *
 157          * Also note that although these lists do not hold a reference to
 158          * the object we can safely grab one here: The final object
 159          * unreferencing and the bound_list are both protected by the
 160          * dev->struct_mutex and so we won't ever be able to observe an
 161          * object on the bound_list with a reference count equals 0.
 162          */
 163         for (phase = phases; phase->list; phase++) {
 164                 struct list_head still_in_list;
 165                 struct drm_i915_gem_object *obj;
 166
 167                 if ((flags & phase->bit) == 0)
 168                         continue;
 169
 170                 INIT_LIST_HEAD(&still_in_list);
 171                 while (count < target &&
 172                        (obj = list_first_entry_or_null(phase->list,
 173                                                        typeof(*obj),
 174                                                        global_list))) {
 175                         list_move_tail(&obj->global_list, &still_in_list);
 176
 177                         if (flags & I915_SHRINK_PURGEABLE &&
 178                             obj->madv != I915_MADV_DONTNEED)
 179                                 continue;
 180
 181                         if (flags & I915_SHRINK_VMAPS &&
 182                             !is_vmalloc_addr(obj->mapping))
 183                                 continue;
 184
 185                         if ((flags & I915_SHRINK_ACTIVE) == 0 &&
 186                             i915_gem_object_is_active(obj))
 187                                 continue;
 188
 189                         if (!can_release_pages(obj))
 190                                 continue;
 191
 192                         i915_gem_object_get(obj);
 193
 194                         /* For the unbound phase, this should be a no-op! */
 195                         i915_gem_object_unbind(obj);
 196                         if (i915_gem_object_put_pages(obj) == 0)
 197                                 count += obj->base.size >> PAGE_SHIFT;
 198
 199                         i915_gem_object_put(obj);
 200                 }
 201                 list_splice(&still_in_list, phase->list);
 202         }
 203
 204         if (flags & I915_SHRINK_BOUND)
 205                 intel_runtime_pm_put(dev_priv);
 206
 207         i915_gem_retire_requests(dev_priv);
 208         /* expedite the RCU grace period to free some request slabs */
 209         synchronize_rcu_expedited();
 210
 211         return count;
 212 }
 213
 214 /**
 215  * i915_gem_shrink_all - Shrink buffer object caches completely
 216  * @dev_priv: i915 device
 217  *
 218  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
 219  * caches completely. It also first waits for and retires all outstanding
 220  * requests to also be able to release backing storage for active objects.
 221  *
 222  * This should only be used in code to intentionally quiescent the gpu or as a
 223  * last-ditch effort when memory seems to have run out.
 224  *
 225  * Returns:
 226  * The number of pages of backing storage actually released.
 227  */
 228 unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 229 {
 230         unsigned long freed;
 231
 232         freed = i915_gem_shrink(dev_priv, -1UL,
 233                                 I915_SHRINK_BOUND |
 234                                 I915_SHRINK_UNBOUND |
 235                                 I915_SHRINK_ACTIVE);
 236         rcu_barrier(); /* wait until our RCU delayed slab frees are completed */
 237
 238         return freed;
 239 }
 240
 241 static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
 242 {
 243         if (!mutex_trylock(&dev->struct_mutex)) {
 244                 if (!mutex_is_locked_by(&dev->struct_mutex, current))
 245                         return false;
 246
 247                 *unlock = false;
 248         } else
 249                 *unlock = true;
 250
 251         return true;
 252 }
 253
 254 static unsigned long
 255 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 256 {
 257         struct drm_i915_private *dev_priv =
 258                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 259         struct drm_device *dev = &dev_priv->drm;
 260         struct drm_i915_gem_object *obj;
 261         unsigned long count;
 262         bool unlock;
 263
 264         if (!i915_gem_shrinker_lock(dev, &unlock))
 265                 return 0;
 266
 267         i915_gem_retire_requests(dev_priv);
 268
 269         count = 0;
 270         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list)
 271                 if (can_release_pages(obj))
 272                         count += obj->base.size >> PAGE_SHIFT;
 273
 274         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 275                 if (!i915_gem_object_is_active(obj) && can_release_pages(obj))
 276                         count += obj->base.size >> PAGE_SHIFT;
 277         }
 278
 279         if (unlock)
 280                 mutex_unlock(&dev->struct_mutex);
 281
 282         return count;
 283 }
 284
 285 static unsigned long
 286 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 287 {
 288         struct drm_i915_private *dev_priv =
 289                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 290         struct drm_device *dev = &dev_priv->drm;
 291         unsigned long freed;
 292         bool unlock;
 293
 294         if (!i915_gem_shrinker_lock(dev, &unlock))
 295                 return SHRINK_STOP;
 296
 297         freed = i915_gem_shrink(dev_priv,
 298                                 sc->nr_to_scan,
 299                                 I915_SHRINK_BOUND |
 300                                 I915_SHRINK_UNBOUND |
 301                                 I915_SHRINK_PURGEABLE);
 302         if (freed < sc->nr_to_scan)
 303                 freed += i915_gem_shrink(dev_priv,
 304                                          sc->nr_to_scan - freed,
 305                                          I915_SHRINK_BOUND |
 306                                          I915_SHRINK_UNBOUND);
 307         if (unlock)
 308                 mutex_unlock(&dev->struct_mutex);
 309
 310         return freed;
 311 }
 312
 313 struct shrinker_lock_uninterruptible {
 314         bool was_interruptible;
 315         bool unlock;
 316 };
 317
 318 static bool
 319 i915_gem_shrinker_lock_uninterruptible(struct drm_i915_private *dev_priv,
 320                                        struct shrinker_lock_uninterruptible *slu,
 321                                        int timeout_ms)
 322 {
 323         unsigned long timeout = jiffies + msecs_to_jiffies_timeout(timeout_ms);
 324
 325         do {
 326                 if (i915_gem_wait_for_idle(dev_priv, 0) == 0 &&
 327                     i915_gem_shrinker_lock(&dev_priv->drm, &slu->unlock))
 328                         break;
 329
 330                 schedule_timeout_killable(1);
 331                 if (fatal_signal_pending(current))
 332                         return false;
 333
 334                 if (time_after(jiffies, timeout)) {
 335                         pr_err("Unable to lock GPU to purge memory.\n");
 336                         return false;
 337                 }
 338         } while (1);
 339
 340         slu->was_interruptible = dev_priv->mm.interruptible;
 341         dev_priv->mm.interruptible = false;
 342         return true;
 343 }
 344
 345 static void
 346 i915_gem_shrinker_unlock_uninterruptible(struct drm_i915_private *dev_priv,
 347                                          struct shrinker_lock_uninterruptible *slu)
 348 {
 349         dev_priv->mm.interruptible = slu->was_interruptible;
 350         if (slu->unlock)
 351                 mutex_unlock(&dev_priv->drm.struct_mutex);
 352 }
 353
 354 static int
 355 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 356 {
 357         struct drm_i915_private *dev_priv =
 358                 container_of(nb, struct drm_i915_private, mm.oom_notifier);
 359         struct shrinker_lock_uninterruptible slu;
 360         struct drm_i915_gem_object *obj;
 361         unsigned long unevictable, bound, unbound, freed_pages;
 362
 363         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 364                 return NOTIFY_DONE;
 365
 366         intel_runtime_pm_get(dev_priv);
 367         freed_pages = i915_gem_shrink_all(dev_priv);
 368         intel_runtime_pm_put(dev_priv);
 369
 370         /* Because we may be allocating inside our own driver, we cannot
 371          * assert that there are no objects with pinned pages that are not
 372          * being pointed to by hardware.
 373          */
 374         unbound = bound = unevictable = 0;
 375         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list) {
 376                 if (!can_release_pages(obj))
 377                         unevictable += obj->base.size >> PAGE_SHIFT;
 378                 else
 379                         unbound += obj->base.size >> PAGE_SHIFT;
 380         }
 381         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 382                 if (!can_release_pages(obj))
 383                         unevictable += obj->base.size >> PAGE_SHIFT;
 384                 else
 385                         bound += obj->base.size >> PAGE_SHIFT;
 386         }
 387
 388         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 389
 390         if (freed_pages || unbound || bound)
 391                 pr_info("Purging GPU memory, %lu pages freed, "
 392                         "%lu pages still pinned.\n",
 393                         freed_pages, unevictable);
 394         if (unbound || bound)
 395                 pr_err("%lu and %lu pages still available in the "
 396                        "bound and unbound GPU page lists.\n",
 397                        bound, unbound);
 398
 399         *(unsigned long *)ptr += freed_pages;
 400         return NOTIFY_DONE;
 401 }
 402
 403 static int
 404 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
 405 {
 406         struct drm_i915_private *dev_priv =
 407                 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
 408         struct shrinker_lock_uninterruptible slu;
 409         struct i915_vma *vma, *next;
 410         unsigned long freed_pages = 0;
 411         int ret;
 412
 413         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 414                 return NOTIFY_DONE;
 415
 416         /* Force everything onto the inactive lists */
 417         ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED);
 418         if (ret)
 419                 goto out;
 420
 421         intel_runtime_pm_get(dev_priv);
 422         freed_pages += i915_gem_shrink(dev_priv, -1UL,
 423                                        I915_SHRINK_BOUND |
 424                                        I915_SHRINK_UNBOUND |
 425                                        I915_SHRINK_ACTIVE |
 426                                        I915_SHRINK_VMAPS);
 427         intel_runtime_pm_put(dev_priv);
 428
 429         /* We also want to clear any cached iomaps as they wrap vmap */
 430         list_for_each_entry_safe(vma, next,
 431                                  &dev_priv->ggtt.base.inactive_list, vm_link) {
 432                 unsigned long count = vma->node.size >> PAGE_SHIFT;
 433                 if (vma->iomap && i915_vma_unbind(vma) == 0)
 434                         freed_pages += count;
 435         }
 436
 437 out:
 438         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 439
 440         *(unsigned long *)ptr += freed_pages;
 441         return NOTIFY_DONE;
 442 }
 443
 444 /**
 445  * i915_gem_shrinker_init - Initialize i915 shrinker
 446  * @dev_priv: i915 device
 447  *
 448  * This function registers and sets up the i915 shrinker and OOM handler.
 449  */
 450 void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
 451 {
 452         dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
 453         dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
 454         dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
 455         WARN_ON(register_shrinker(&dev_priv->mm.shrinker));
 456
 457         dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 458         WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));
 459
 460         dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
 461         WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 462 }
 463
 464 /**
 465  * i915_gem_shrinker_cleanup - Clean up i915 shrinker
 466  * @dev_priv: i915 device
 467  *
 468  * This function unregisters the i915 shrinker and OOM handler.
 469  */
 470 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
 471 {
 472         WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 473         WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 474         unregister_shrinker(&dev_priv->mm.shrinker);
 475 }