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_SMP) || defined(CONFIG_DEBUG_MUTEXES)
  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 int num_vma_bound(struct drm_i915_gem_object *obj)
  52 {
  53         struct i915_vma *vma;
  54         int count = 0;
  55
  56         list_for_each_entry(vma, &obj->vma_list, obj_link) {
  57                 if (drm_mm_node_allocated(&vma->node))
  58                         count++;
  59                 if (vma->pin_count)
  60                         count++;
  61         }
  62
  63         return count;
  64 }
  65
  66 static bool swap_available(void)
  67 {
  68         return get_nr_swap_pages() > 0;
  69 }
  70
  71 static bool can_release_pages(struct drm_i915_gem_object *obj)
  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 != num_vma_bound(obj))
  82                 return false;
  83
  84         /* We can only return physical pages to the system if we can either
  85          * discard the contents (because the user has marked them as being
  86          * purgeable) or if we can move their contents out to swap.
  87          */
  88         return swap_available() || obj->madv == I915_MADV_DONTNEED;
  89 }
  90
  91 /**
  92  * i915_gem_shrink - Shrink buffer object caches
  93  * @dev_priv: i915 device
  94  * @target: amount of memory to make available, in pages
  95  * @flags: control flags for selecting cache types
  96  *
  97  * This function is the main interface to the shrinker. It will try to release
  98  * up to @target pages of main memory backing storage from buffer objects.
  99  * Selection of the specific caches can be done with @flags. This is e.g. useful
 100  * when purgeable objects should be removed from caches preferentially.
 101  *
 102  * Note that it's not guaranteed that released amount is actually available as
 103  * free system memory - the pages might still be in-used to due to other reasons
 104  * (like cpu mmaps) or the mm core has reused them before we could grab them.
 105  * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
 106  * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
 107  *
 108  * Also note that any kind of pinning (both per-vma address space pins and
 109  * backing storage pins at the buffer object level) result in the shrinker code
 110  * having to skip the object.
 111  *
 112  * Returns:
 113  * The number of pages of backing storage actually released.
 114  */
 115 unsigned long
 116 i915_gem_shrink(struct drm_i915_private *dev_priv,
 117                 unsigned long target, unsigned flags)
 118 {
 119         const struct {
 120                 struct list_head *list;
 121                 unsigned int bit;
 122         } phases[] = {
 123                 { &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
 124                 { &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
 125                 { NULL, 0 },
 126         }, *phase;
 127         unsigned long count = 0;
 128
 129         trace_i915_gem_shrink(dev_priv, target, flags);
 130         i915_gem_retire_requests(dev_priv->dev);
 131
 132         /*
 133          * As we may completely rewrite the (un)bound list whilst unbinding
 134          * (due to retiring requests) we have to strictly process only
 135          * one element of the list at the time, and recheck the list
 136          * on every iteration.
 137          *
 138          * In particular, we must hold a reference whilst removing the
 139          * object as we may end up waiting for and/or retiring the objects.
 140          * This might release the final reference (held by the active list)
 141          * and result in the object being freed from under us. This is
 142          * similar to the precautions the eviction code must take whilst
 143          * removing objects.
 144          *
 145          * Also note that although these lists do not hold a reference to
 146          * the object we can safely grab one here: The final object
 147          * unreferencing and the bound_list are both protected by the
 148          * dev->struct_mutex and so we won't ever be able to observe an
 149          * object on the bound_list with a reference count equals 0.
 150          */
 151         for (phase = phases; phase->list; phase++) {
 152                 struct list_head still_in_list;
 153
 154                 if ((flags & phase->bit) == 0)
 155                         continue;
 156
 157                 INIT_LIST_HEAD(&still_in_list);
 158                 while (count < target && !list_empty(phase->list)) {
 159                         struct drm_i915_gem_object *obj;
 160                         struct i915_vma *vma, *v;
 161
 162                         obj = list_first_entry(phase->list,
 163                                                typeof(*obj), global_list);
 164                         list_move_tail(&obj->global_list, &still_in_list);
 165
 166                         if (flags & I915_SHRINK_PURGEABLE &&
 167                             obj->madv != I915_MADV_DONTNEED)
 168                                 continue;
 169
 170                         if (flags & I915_SHRINK_VMAPS &&
 171                             !is_vmalloc_addr(obj->mapping))
 172                                 continue;
 173
 174                         if ((flags & I915_SHRINK_ACTIVE) == 0 && obj->active)
 175                                 continue;
 176
 177                         if (!can_release_pages(obj))
 178                                 continue;
 179
 180                         drm_gem_object_reference(&obj->base);
 181
 182                         /* For the unbound phase, this should be a no-op! */
 183                         list_for_each_entry_safe(vma, v,
 184                                                  &obj->vma_list, obj_link)
 185                                 if (i915_vma_unbind(vma))
 186                                         break;
 187
 188                         if (i915_gem_object_put_pages(obj) == 0)
 189                                 count += obj->base.size >> PAGE_SHIFT;
 190
 191                         drm_gem_object_unreference(&obj->base);
 192                 }
 193                 list_splice(&still_in_list, phase->list);
 194         }
 195
 196         i915_gem_retire_requests(dev_priv->dev);
 197
 198         return count;
 199 }
 200
 201 /**
 202  * i915_gem_shrink_all - Shrink buffer object caches completely
 203  * @dev_priv: i915 device
 204  *
 205  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
 206  * caches completely. It also first waits for and retires all outstanding
 207  * requests to also be able to release backing storage for active objects.
 208  *
 209  * This should only be used in code to intentionally quiescent the gpu or as a
 210  * last-ditch effort when memory seems to have run out.
 211  *
 212  * Returns:
 213  * The number of pages of backing storage actually released.
 214  */
 215 unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 216 {
 217         return i915_gem_shrink(dev_priv, -1UL,
 218                                I915_SHRINK_BOUND |
 219                                I915_SHRINK_UNBOUND |
 220                                I915_SHRINK_ACTIVE);
 221 }
 222
 223 static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
 224 {
 225         if (!mutex_trylock(&dev->struct_mutex)) {
 226                 if (!mutex_is_locked_by(&dev->struct_mutex, current))
 227                         return false;
 228
 229                 if (to_i915(dev)->mm.shrinker_no_lock_stealing)
 230                         return false;
 231
 232                 *unlock = false;
 233         } else
 234                 *unlock = true;
 235
 236         return true;
 237 }
 238
 239 static unsigned long
 240 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 241 {
 242         struct drm_i915_private *dev_priv =
 243                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 244         struct drm_device *dev = dev_priv->dev;
 245         struct drm_i915_gem_object *obj;
 246         unsigned long count;
 247         bool unlock;
 248
 249         if (!i915_gem_shrinker_lock(dev, &unlock))
 250                 return 0;
 251
 252         count = 0;
 253         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list)
 254                 if (can_release_pages(obj))
 255                         count += obj->base.size >> PAGE_SHIFT;
 256
 257         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 258                 if (!obj->active && can_release_pages(obj))
 259                         count += obj->base.size >> PAGE_SHIFT;
 260         }
 261
 262         if (unlock)
 263                 mutex_unlock(&dev->struct_mutex);
 264
 265         return count;
 266 }
 267
 268 static unsigned long
 269 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 270 {
 271         struct drm_i915_private *dev_priv =
 272                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 273         struct drm_device *dev = dev_priv->dev;
 274         unsigned long freed;
 275         bool unlock;
 276
 277         if (!i915_gem_shrinker_lock(dev, &unlock))
 278                 return SHRINK_STOP;
 279
 280         freed = i915_gem_shrink(dev_priv,
 281                                 sc->nr_to_scan,
 282                                 I915_SHRINK_BOUND |
 283                                 I915_SHRINK_UNBOUND |
 284                                 I915_SHRINK_PURGEABLE);
 285         if (freed < sc->nr_to_scan)
 286                 freed += i915_gem_shrink(dev_priv,
 287                                          sc->nr_to_scan - freed,
 288                                          I915_SHRINK_BOUND |
 289                                          I915_SHRINK_UNBOUND);
 290         if (unlock)
 291                 mutex_unlock(&dev->struct_mutex);
 292
 293         return freed;
 294 }
 295
 296 struct shrinker_lock_uninterruptible {
 297         bool was_interruptible;
 298         bool unlock;
 299 };
 300
 301 static bool
 302 i915_gem_shrinker_lock_uninterruptible(struct drm_i915_private *dev_priv,
 303                                        struct shrinker_lock_uninterruptible *slu,
 304                                        int timeout_ms)
 305 {
 306         unsigned long timeout = msecs_to_jiffies(timeout_ms) + 1;
 307
 308         while (!i915_gem_shrinker_lock(dev_priv->dev, &slu->unlock)) {
 309                 schedule_timeout_killable(1);
 310                 if (fatal_signal_pending(current))
 311                         return false;
 312                 if (--timeout == 0) {
 313                         pr_err("Unable to lock GPU to purge memory.\n");
 314                         return false;
 315                 }
 316         }
 317
 318         slu->was_interruptible = dev_priv->mm.interruptible;
 319         dev_priv->mm.interruptible = false;
 320         return true;
 321 }
 322
 323 static void
 324 i915_gem_shrinker_unlock_uninterruptible(struct drm_i915_private *dev_priv,
 325                                          struct shrinker_lock_uninterruptible *slu)
 326 {
 327         dev_priv->mm.interruptible = slu->was_interruptible;
 328         if (slu->unlock)
 329                 mutex_unlock(&dev_priv->dev->struct_mutex);
 330 }
 331
 332 static int
 333 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 334 {
 335         struct drm_i915_private *dev_priv =
 336                 container_of(nb, struct drm_i915_private, mm.oom_notifier);
 337         struct shrinker_lock_uninterruptible slu;
 338         struct drm_i915_gem_object *obj;
 339         unsigned long pinned, bound, unbound, freed_pages;
 340
 341         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 342                 return NOTIFY_DONE;
 343
 344         freed_pages = i915_gem_shrink_all(dev_priv);
 345
 346         /* Because we may be allocating inside our own driver, we cannot
 347          * assert that there are no objects with pinned pages that are not
 348          * being pointed to by hardware.
 349          */
 350         unbound = bound = pinned = 0;
 351         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list) {
 352                 if (!obj->base.filp) /* not backed by a freeable object */
 353                         continue;
 354
 355                 if (obj->pages_pin_count)
 356                         pinned += obj->base.size;
 357                 else
 358                         unbound += obj->base.size;
 359         }
 360         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 361                 if (!obj->base.filp)
 362                         continue;
 363
 364                 if (obj->pages_pin_count)
 365                         pinned += obj->base.size;
 366                 else
 367                         bound += obj->base.size;
 368         }
 369
 370         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 371
 372         if (freed_pages || unbound || bound)
 373                 pr_info("Purging GPU memory, %lu bytes freed, %lu bytes still pinned.\n",
 374                         freed_pages << PAGE_SHIFT, pinned);
 375         if (unbound || bound)
 376                 pr_err("%lu and %lu bytes still available in the "
 377                        "bound and unbound GPU page lists.\n",
 378                        bound, unbound);
 379
 380         *(unsigned long *)ptr += freed_pages;
 381         return NOTIFY_DONE;
 382 }
 383
 384 static int
 385 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
 386 {
 387         struct drm_i915_private *dev_priv =
 388                 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
 389         struct shrinker_lock_uninterruptible slu;
 390         unsigned long freed_pages;
 391
 392         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 393                 return NOTIFY_DONE;
 394
 395         freed_pages = i915_gem_shrink(dev_priv, -1UL,
 396                                       I915_SHRINK_BOUND |
 397                                       I915_SHRINK_UNBOUND |
 398                                       I915_SHRINK_ACTIVE |
 399                                       I915_SHRINK_VMAPS);
 400
 401         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 402
 403         *(unsigned long *)ptr += freed_pages;
 404         return NOTIFY_DONE;
 405 }
 406
 407 /**
 408  * i915_gem_shrinker_init - Initialize i915 shrinker
 409  * @dev_priv: i915 device
 410  *
 411  * This function registers and sets up the i915 shrinker and OOM handler.
 412  */
 413 void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
 414 {
 415         dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
 416         dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
 417         dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
 418         WARN_ON(register_shrinker(&dev_priv->mm.shrinker));
 419
 420         dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 421         WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));
 422
 423         dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
 424         WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 425 }
 426
 427 /**
 428  * i915_gem_shrinker_cleanup - Clean up i915 shrinker
 429  * @dev_priv: i915 device
 430  *
 431  * This function unregisters the i915 shrinker and OOM handler.
 432  */
 433 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
 434 {
 435         WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 436         WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 437         unregister_shrinker(&dev_priv->mm.shrinker);
 438 }