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 shmemfs objects are backed by swap */
  74         if (!obj->base.filp)
  75                 return false;
  76
  77         /* Only report true if by unbinding the object and putting its pages
  78          * we can actually make forward progress towards freeing physical
  79          * pages.
  80          *
  81          * If the pages are pinned for any other reason than being bound
  82          * to the GPU, simply unbinding from the GPU is not going to succeed
  83          * in releasing our pin count on the pages themselves.
  84          */
  85         if (obj->pages_pin_count != num_vma_bound(obj))
  86                 return false;
  87
  88         /* We can only return physical pages to the system if we can either
  89          * discard the contents (because the user has marked them as being
  90          * purgeable) or if we can move their contents out to swap.
  91          */
  92         return swap_available() || obj->madv == I915_MADV_DONTNEED;
  93 }
  94
  95 /**
  96  * i915_gem_shrink - Shrink buffer object caches
  97  * @dev_priv: i915 device
  98  * @target: amount of memory to make available, in pages
  99  * @flags: control flags for selecting cache types
 100  *
 101  * This function is the main interface to the shrinker. It will try to release
 102  * up to @target pages of main memory backing storage from buffer objects.
 103  * Selection of the specific caches can be done with @flags. This is e.g. useful
 104  * when purgeable objects should be removed from caches preferentially.
 105  *
 106  * Note that it's not guaranteed that released amount is actually available as
 107  * free system memory - the pages might still be in-used to due to other reasons
 108  * (like cpu mmaps) or the mm core has reused them before we could grab them.
 109  * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
 110  * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
 111  *
 112  * Also note that any kind of pinning (both per-vma address space pins and
 113  * backing storage pins at the buffer object level) result in the shrinker code
 114  * having to skip the object.
 115  *
 116  * Returns:
 117  * The number of pages of backing storage actually released.
 118  */
 119 unsigned long
 120 i915_gem_shrink(struct drm_i915_private *dev_priv,
 121                 unsigned long target, unsigned flags)
 122 {
 123         const struct {
 124                 struct list_head *list;
 125                 unsigned int bit;
 126         } phases[] = {
 127                 { &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
 128                 { &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
 129                 { NULL, 0 },
 130         }, *phase;
 131         unsigned long count = 0;
 132
 133         trace_i915_gem_shrink(dev_priv, target, flags);
 134         i915_gem_retire_requests(dev_priv->dev);
 135
 136         /*
 137          * As we may completely rewrite the (un)bound list whilst unbinding
 138          * (due to retiring requests) we have to strictly process only
 139          * one element of the list at the time, and recheck the list
 140          * on every iteration.
 141          *
 142          * In particular, we must hold a reference whilst removing the
 143          * object as we may end up waiting for and/or retiring the objects.
 144          * This might release the final reference (held by the active list)
 145          * and result in the object being freed from under us. This is
 146          * similar to the precautions the eviction code must take whilst
 147          * removing objects.
 148          *
 149          * Also note that although these lists do not hold a reference to
 150          * the object we can safely grab one here: The final object
 151          * unreferencing and the bound_list are both protected by the
 152          * dev->struct_mutex and so we won't ever be able to observe an
 153          * object on the bound_list with a reference count equals 0.
 154          */
 155         for (phase = phases; phase->list; phase++) {
 156                 struct list_head still_in_list;
 157
 158                 if ((flags & phase->bit) == 0)
 159                         continue;
 160
 161                 INIT_LIST_HEAD(&still_in_list);
 162                 while (count < target && !list_empty(phase->list)) {
 163                         struct drm_i915_gem_object *obj;
 164                         struct i915_vma *vma, *v;
 165
 166                         obj = list_first_entry(phase->list,
 167                                                typeof(*obj), global_list);
 168                         list_move_tail(&obj->global_list, &still_in_list);
 169
 170                         if (flags & I915_SHRINK_PURGEABLE &&
 171                             obj->madv != I915_MADV_DONTNEED)
 172                                 continue;
 173
 174                         if (flags & I915_SHRINK_VMAPS &&
 175                             !is_vmalloc_addr(obj->mapping))
 176                                 continue;
 177
 178                         if ((flags & I915_SHRINK_ACTIVE) == 0 && obj->active)
 179                                 continue;
 180
 181                         if (!can_release_pages(obj))
 182                                 continue;
 183
 184                         drm_gem_object_reference(&obj->base);
 185
 186                         /* For the unbound phase, this should be a no-op! */
 187                         list_for_each_entry_safe(vma, v,
 188                                                  &obj->vma_list, obj_link)
 189                                 if (i915_vma_unbind(vma))
 190                                         break;
 191
 192                         if (i915_gem_object_put_pages(obj) == 0)
 193                                 count += obj->base.size >> PAGE_SHIFT;
 194
 195                         drm_gem_object_unreference(&obj->base);
 196                 }
 197                 list_splice(&still_in_list, phase->list);
 198         }
 199
 200         i915_gem_retire_requests(dev_priv->dev);
 201
 202         return count;
 203 }
 204
 205 /**
 206  * i915_gem_shrink_all - Shrink buffer object caches completely
 207  * @dev_priv: i915 device
 208  *
 209  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
 210  * caches completely. It also first waits for and retires all outstanding
 211  * requests to also be able to release backing storage for active objects.
 212  *
 213  * This should only be used in code to intentionally quiescent the gpu or as a
 214  * last-ditch effort when memory seems to have run out.
 215  *
 216  * Returns:
 217  * The number of pages of backing storage actually released.
 218  */
 219 unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 220 {
 221         return i915_gem_shrink(dev_priv, -1UL,
 222                                I915_SHRINK_BOUND |
 223                                I915_SHRINK_UNBOUND |
 224                                I915_SHRINK_ACTIVE);
 225 }
 226
 227 static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
 228 {
 229         if (!mutex_trylock(&dev->struct_mutex)) {
 230                 if (!mutex_is_locked_by(&dev->struct_mutex, current))
 231                         return false;
 232
 233                 if (to_i915(dev)->mm.shrinker_no_lock_stealing)
 234                         return false;
 235
 236                 *unlock = false;
 237         } else
 238                 *unlock = true;
 239
 240         return true;
 241 }
 242
 243 static unsigned long
 244 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 245 {
 246         struct drm_i915_private *dev_priv =
 247                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 248         struct drm_device *dev = dev_priv->dev;
 249         struct drm_i915_gem_object *obj;
 250         unsigned long count;
 251         bool unlock;
 252
 253         if (!i915_gem_shrinker_lock(dev, &unlock))
 254                 return 0;
 255
 256         count = 0;
 257         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list)
 258                 if (can_release_pages(obj))
 259                         count += obj->base.size >> PAGE_SHIFT;
 260
 261         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 262                 if (!obj->active && can_release_pages(obj))
 263                         count += obj->base.size >> PAGE_SHIFT;
 264         }
 265
 266         if (unlock)
 267                 mutex_unlock(&dev->struct_mutex);
 268
 269         return count;
 270 }
 271
 272 static unsigned long
 273 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 274 {
 275         struct drm_i915_private *dev_priv =
 276                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 277         struct drm_device *dev = dev_priv->dev;
 278         unsigned long freed;
 279         bool unlock;
 280
 281         if (!i915_gem_shrinker_lock(dev, &unlock))
 282                 return SHRINK_STOP;
 283
 284         freed = i915_gem_shrink(dev_priv,
 285                                 sc->nr_to_scan,
 286                                 I915_SHRINK_BOUND |
 287                                 I915_SHRINK_UNBOUND |
 288                                 I915_SHRINK_PURGEABLE);
 289         if (freed < sc->nr_to_scan)
 290                 freed += i915_gem_shrink(dev_priv,
 291                                          sc->nr_to_scan - freed,
 292                                          I915_SHRINK_BOUND |
 293                                          I915_SHRINK_UNBOUND);
 294         if (unlock)
 295                 mutex_unlock(&dev->struct_mutex);
 296
 297         return freed;
 298 }
 299
 300 struct shrinker_lock_uninterruptible {
 301         bool was_interruptible;
 302         bool unlock;
 303 };
 304
 305 static bool
 306 i915_gem_shrinker_lock_uninterruptible(struct drm_i915_private *dev_priv,
 307                                        struct shrinker_lock_uninterruptible *slu,
 308                                        int timeout_ms)
 309 {
 310         unsigned long timeout = msecs_to_jiffies(timeout_ms) + 1;
 311
 312         while (!i915_gem_shrinker_lock(dev_priv->dev, &slu->unlock)) {
 313                 schedule_timeout_killable(1);
 314                 if (fatal_signal_pending(current))
 315                         return false;
 316                 if (--timeout == 0) {
 317                         pr_err("Unable to lock GPU to purge memory.\n");
 318                         return false;
 319                 }
 320         }
 321
 322         slu->was_interruptible = dev_priv->mm.interruptible;
 323         dev_priv->mm.interruptible = false;
 324         return true;
 325 }
 326
 327 static void
 328 i915_gem_shrinker_unlock_uninterruptible(struct drm_i915_private *dev_priv,
 329                                          struct shrinker_lock_uninterruptible *slu)
 330 {
 331         dev_priv->mm.interruptible = slu->was_interruptible;
 332         if (slu->unlock)
 333                 mutex_unlock(&dev_priv->dev->struct_mutex);
 334 }
 335
 336 static int
 337 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 338 {
 339         struct drm_i915_private *dev_priv =
 340                 container_of(nb, struct drm_i915_private, mm.oom_notifier);
 341         struct shrinker_lock_uninterruptible slu;
 342         struct drm_i915_gem_object *obj;
 343         unsigned long unevictable, bound, unbound, freed_pages;
 344
 345         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 346                 return NOTIFY_DONE;
 347
 348         freed_pages = i915_gem_shrink_all(dev_priv);
 349
 350         /* Because we may be allocating inside our own driver, we cannot
 351          * assert that there are no objects with pinned pages that are not
 352          * being pointed to by hardware.
 353          */
 354         unbound = bound = unevictable = 0;
 355         list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list) {
 356                 if (!can_release_pages(obj))
 357                         unevictable += obj->base.size >> PAGE_SHIFT;
 358                 else
 359                         unbound += obj->base.size >> PAGE_SHIFT;
 360         }
 361         list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
 362                 if (!can_release_pages(obj))
 363                         unevictable += obj->base.size >> PAGE_SHIFT;
 364                 else
 365                         bound += obj->base.size >> PAGE_SHIFT;
 366         }
 367
 368         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 369
 370         if (freed_pages || unbound || bound)
 371                 pr_info("Purging GPU memory, %lu pages freed, "
 372                         "%lu pages still pinned.\n",
 373                         freed_pages, unevictable);
 374         if (unbound || bound)
 375                 pr_err("%lu and %lu pages still available in the "
 376                        "bound and unbound GPU page lists.\n",
 377                        bound, unbound);
 378
 379         *(unsigned long *)ptr += freed_pages;
 380         return NOTIFY_DONE;
 381 }
 382
 383 static int
 384 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
 385 {
 386         struct drm_i915_private *dev_priv =
 387                 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
 388         struct shrinker_lock_uninterruptible slu;
 389         unsigned long freed_pages;
 390
 391         if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 392                 return NOTIFY_DONE;
 393
 394         freed_pages = i915_gem_shrink(dev_priv, -1UL,
 395                                       I915_SHRINK_BOUND |
 396                                       I915_SHRINK_UNBOUND |
 397                                       I915_SHRINK_ACTIVE |
 398                                       I915_SHRINK_VMAPS);
 399
 400         i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);
 401
 402         *(unsigned long *)ptr += freed_pages;
 403         return NOTIFY_DONE;
 404 }
 405
 406 /**
 407  * i915_gem_shrinker_init - Initialize i915 shrinker
 408  * @dev_priv: i915 device
 409  *
 410  * This function registers and sets up the i915 shrinker and OOM handler.
 411  */
 412 void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
 413 {
 414         dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
 415         dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
 416         dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
 417         WARN_ON(register_shrinker(&dev_priv->mm.shrinker));
 418
 419         dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 420         WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));
 421
 422         dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
 423         WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 424 }
 425
 426 /**
 427  * i915_gem_shrinker_cleanup - Clean up i915 shrinker
 428  * @dev_priv: i915 device
 429  *
 430  * This function unregisters the i915 shrinker and OOM handler.
 431  */
 432 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
 433 {
 434         WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 435         WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 436         unregister_shrinker(&dev_priv->mm.shrinker);
 437 }