sys/dev/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 shrinker_lock(struct drm_i915_private *dev_priv, bool *unlock)
  39 {
  40         switch (mutex_trylock_recursive(&dev_priv->drm.struct_mutex)) {
  41         case MUTEX_TRYLOCK_RECURSIVE:
  42                 *unlock = false;
  43                 return true;
  44
  45         case MUTEX_TRYLOCK_FAILED:
  46                 *unlock = false;
  47                 preempt_disable();
  48                 do {
  49                         cpu_relax();
  50                         if (mutex_trylock(&dev_priv->drm.struct_mutex)) {
  51                                 *unlock = true;
  52                                 break;
  53                         }
  54                 } while (!need_resched());
  55                 preempt_enable();
  56                 return *unlock;
  57
  58         case MUTEX_TRYLOCK_SUCCESS:
  59                 *unlock = true;
  60                 return true;
  61         }
  62
  63         BUG();
  64 }
  65
  66 static void shrinker_unlock(struct drm_i915_private *dev_priv, bool unlock)
  67 {
  68         if (!unlock)
  69                 return;
  70
  71         mutex_unlock(&dev_priv->drm.struct_mutex);
  72 }
  73
  74 static bool swap_available(void)
  75 {
  76         return get_nr_swap_pages() > 0;
  77 }
  78
  79 static bool can_release_pages(struct drm_i915_gem_object *obj)
  80 {
  81         /* Consider only shrinkable ojects. */
  82         if (!i915_gem_object_is_shrinkable(obj))
  83                 return false;
  84
  85         /* Only report true if by unbinding the object and putting its pages
  86          * we can actually make forward progress towards freeing physical
  87          * pages.
  88          *
  89          * If the pages are pinned for any other reason than being bound
  90          * to the GPU, simply unbinding from the GPU is not going to succeed
  91          * in releasing our pin count on the pages themselves.
  92          */
  93         if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count)
  94                 return false;
  95
  96         /* If any vma are "permanently" pinned, it will prevent us from
  97          * reclaiming the obj->mm.pages. We only allow scanout objects to claim
  98          * a permanent pin, along with a few others like the context objects.
  99          * To simplify the scan, and to avoid walking the list of vma under the
 100          * object, we just check the count of its permanently pinned.
 101          */
 102         if (READ_ONCE(obj->pin_global))
 103                 return false;
 104
 105         /* We can only return physical pages to the system if we can either
 106          * discard the contents (because the user has marked them as being
 107          * purgeable) or if we can move their contents out to swap.
 108          */
 109         return swap_available() || obj->mm.madv == I915_MADV_DONTNEED;
 110 }
 111
 112 static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
 113 {
 114         if (i915_gem_object_unbind(obj) == 0)
 115                 __i915_gem_object_put_pages(obj, I915_MM_SHRINKER);
 116         return !i915_gem_object_has_pages(obj);
 117 }
 118
 119 /**
 120  * i915_gem_shrink - Shrink buffer object caches
 121  * @dev_priv: i915 device
 122  * @target: amount of memory to make available, in pages
 123  * @nr_scanned: optional output for number of pages scanned (incremental)
 124  * @flags: control flags for selecting cache types
 125  *
 126  * This function is the main interface to the shrinker. It will try to release
 127  * up to @target pages of main memory backing storage from buffer objects.
 128  * Selection of the specific caches can be done with @flags. This is e.g. useful
 129  * when purgeable objects should be removed from caches preferentially.
 130  *
 131  * Note that it's not guaranteed that released amount is actually available as
 132  * free system memory - the pages might still be in-used to due to other reasons
 133  * (like cpu mmaps) or the mm core has reused them before we could grab them.
 134  * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
 135  * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
 136  *
 137  * Also note that any kind of pinning (both per-vma address space pins and
 138  * backing storage pins at the buffer object level) result in the shrinker code
 139  * having to skip the object.
 140  *
 141  * Returns:
 142  * The number of pages of backing storage actually released.
 143  */
 144 unsigned long
 145 i915_gem_shrink(struct drm_i915_private *dev_priv,
 146                 unsigned long target,
 147                 unsigned long *nr_scanned,
 148                 unsigned flags)
 149 {
 150         const struct {
 151                 struct list_head *list;
 152                 unsigned int bit;
 153         } phases[] = {
 154                 { &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
 155                 { &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
 156                 { NULL, 0 },
 157         }, *phase;
 158         unsigned long count = 0;
 159         unsigned long scanned = 0;
 160         bool unlock;
 161
 162         if (!shrinker_lock(dev_priv, &unlock))
 163                 return 0;
 164
 165         /*
 166          * When shrinking the active list, also consider active contexts.
 167          * Active contexts are pinned until they are retired, and so can
 168          * not be simply unbound to retire and unpin their pages. To shrink
 169          * the contexts, we must wait until the gpu is idle.
 170          *
 171          * We don't care about errors here; if we cannot wait upon the GPU,
 172          * we will free as much as we can and hope to get a second chance.
 173          */
 174         if (flags & I915_SHRINK_ACTIVE)
 175                 i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED);
 176
 177         trace_i915_gem_shrink(dev_priv, target, flags);
 178         i915_gem_retire_requests(dev_priv);
 179
 180         /*
 181          * Unbinding of objects will require HW access; Let us not wake the
 182          * device just to recover a little memory. If absolutely necessary,
 183          * we will force the wake during oom-notifier.
 184          */
 185         if ((flags & I915_SHRINK_BOUND) &&
 186             !intel_runtime_pm_get_if_in_use(dev_priv))
 187                 flags &= ~I915_SHRINK_BOUND;
 188
 189         /*
 190          * As we may completely rewrite the (un)bound list whilst unbinding
 191          * (due to retiring requests) we have to strictly process only
 192          * one element of the list at the time, and recheck the list
 193          * on every iteration.
 194          *
 195          * In particular, we must hold a reference whilst removing the
 196          * object as we may end up waiting for and/or retiring the objects.
 197          * This might release the final reference (held by the active list)
 198          * and result in the object being freed from under us. This is
 199          * similar to the precautions the eviction code must take whilst
 200          * removing objects.
 201          *
 202          * Also note that although these lists do not hold a reference to
 203          * the object we can safely grab one here: The final object
 204          * unreferencing and the bound_list are both protected by the
 205          * dev->struct_mutex and so we won't ever be able to observe an
 206          * object on the bound_list with a reference count equals 0.
 207          */
 208         for (phase = phases; phase->list; phase++) {
 209                 struct list_head still_in_list;
 210                 struct drm_i915_gem_object *obj;
 211
 212                 if ((flags & phase->bit) == 0)
 213                         continue;
 214
 215                 INIT_LIST_HEAD(&still_in_list);
 216
 217                 /*
 218                  * We serialize our access to unreferenced objects through
 219                  * the use of the struct_mutex. While the objects are not
 220                  * yet freed (due to RCU then a workqueue) we still want
 221                  * to be able to shrink their pages, so they remain on
 222                  * the unbound/bound list until actually freed.
 223                  */
 224                 lockmgr(&dev_priv->mm.obj_lock, LK_EXCLUSIVE);
 225                 while (count < target &&
 226                        (obj = list_first_entry_or_null(phase->list,
 227                                                        typeof(*obj),
 228                                                        mm.link))) {
 229                         list_move_tail(&obj->mm.link, &still_in_list);
 230
 231                         if (flags & I915_SHRINK_PURGEABLE &&
 232                             obj->mm.madv != I915_MADV_DONTNEED)
 233                                 continue;
 234
 235                         if (flags & I915_SHRINK_VMAPS &&
 236                             !is_vmalloc_addr(obj->mm.mapping))
 237                                 continue;
 238
 239                         if (!(flags & I915_SHRINK_ACTIVE) &&
 240                             (i915_gem_object_is_active(obj) ||
 241                              i915_gem_object_is_framebuffer(obj)))
 242                                 continue;
 243
 244                         if (!can_release_pages(obj))
 245                                 continue;
 246
 247                         lockmgr(&dev_priv->mm.obj_lock, LK_RELEASE);
 248
 249                         if (unsafe_drop_pages(obj)) {
 250                                 /* May arrive from get_pages on another bo */
 251                                 mutex_lock_nested(&obj->mm.lock,
 252                                                   I915_MM_SHRINKER);
 253                                 if (!i915_gem_object_has_pages(obj)) {
 254                                         __i915_gem_object_invalidate(obj);
 255                                         count += obj->base.size >> PAGE_SHIFT;
 256                                 }
 257                                 mutex_unlock(&obj->mm.lock);
 258                         }
 259                         scanned += obj->base.size >> PAGE_SHIFT;
 260
 261                         lockmgr(&dev_priv->mm.obj_lock, LK_EXCLUSIVE);
 262                 }
 263                 list_splice_tail(&still_in_list, phase->list);
 264                 lockmgr(&dev_priv->mm.obj_lock, LK_RELEASE);
 265         }
 266
 267         if (flags & I915_SHRINK_BOUND)
 268                 intel_runtime_pm_put(dev_priv);
 269
 270         i915_gem_retire_requests(dev_priv);
 271
 272         shrinker_unlock(dev_priv, unlock);
 273
 274         if (nr_scanned)
 275                 *nr_scanned += scanned;
 276         return count;
 277 }
 278
 279 /**
 280  * i915_gem_shrink_all - Shrink buffer object caches completely
 281  * @dev_priv: i915 device
 282  *
 283  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
 284  * caches completely. It also first waits for and retires all outstanding
 285  * requests to also be able to release backing storage for active objects.
 286  *
 287  * This should only be used in code to intentionally quiescent the gpu or as a
 288  * last-ditch effort when memory seems to have run out.
 289  *
 290  * Returns:
 291  * The number of pages of backing storage actually released.
 292  */
 293 unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 294 {
 295         unsigned long freed;
 296
 297         intel_runtime_pm_get(dev_priv);
 298         freed = i915_gem_shrink(dev_priv, -1UL, NULL,
 299                                 I915_SHRINK_BOUND |
 300                                 I915_SHRINK_UNBOUND |
 301                                 I915_SHRINK_ACTIVE);
 302         intel_runtime_pm_put(dev_priv);
 303
 304         return freed;
 305 }
 306
 307 static unsigned long
 308 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
 309 {
 310 #if 0
 311         struct drm_i915_private *dev_priv =
 312                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 313         struct drm_i915_gem_object *obj;
 314         unsigned long count = 0;
 315
 316         spin_lock(&dev_priv->mm.obj_lock);
 317         list_for_each_entry(obj, &dev_priv->mm.unbound_list, mm.link)
 318                 if (can_release_pages(obj))
 319                         count += obj->base.size >> PAGE_SHIFT;
 320
 321         list_for_each_entry(obj, &dev_priv->mm.bound_list, mm.link)
 322                 if (!i915_gem_object_is_active(obj) && can_release_pages(obj))
 323                         count += obj->base.size >> PAGE_SHIFT;
 324         spin_unlock(&dev_priv->mm.obj_lock);
 325
 326         return count;
 327 #endif
 328         return 0;
 329 }
 330
 331 static unsigned long
 332 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 333 {
 334 #if 0
 335         struct drm_i915_private *dev_priv =
 336                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
 337         unsigned long freed;
 338         bool unlock;
 339
 340         sc->nr_scanned = 0;
 341
 342         if (!shrinker_lock(dev_priv, &unlock))
 343                 return SHRINK_STOP;
 344
 345         freed = i915_gem_shrink(dev_priv,
 346                                 sc->nr_to_scan,
 347                                 &sc->nr_scanned,
 348                                 I915_SHRINK_BOUND |
 349                                 I915_SHRINK_UNBOUND |
 350                                 I915_SHRINK_PURGEABLE);
 351         if (freed < sc->nr_to_scan)
 352                 freed += i915_gem_shrink(dev_priv,
 353                                          sc->nr_to_scan - sc->nr_scanned,
 354                                          &sc->nr_scanned,
 355                                          I915_SHRINK_BOUND |
 356                                          I915_SHRINK_UNBOUND);
 357         if (freed < sc->nr_to_scan && current_is_kswapd()) {
 358                 intel_runtime_pm_get(dev_priv);
 359                 freed += i915_gem_shrink(dev_priv,
 360                                          sc->nr_to_scan - sc->nr_scanned,
 361                                          &sc->nr_scanned,
 362                                          I915_SHRINK_ACTIVE |
 363                                          I915_SHRINK_BOUND |
 364                                          I915_SHRINK_UNBOUND);
 365                 intel_runtime_pm_put(dev_priv);
 366         }
 367
 368         shrinker_unlock(dev_priv, unlock);
 369
 370         return freed;
 371 #endif
 372         return 0;
 373 }
 374
 375 #if 0
 376 static bool
 377 shrinker_lock_uninterruptible(struct drm_i915_private *dev_priv, bool *unlock,
 378                               int timeout_ms)
 379 {
 380         unsigned long timeout = jiffies + msecs_to_jiffies_timeout(timeout_ms);
 381
 382         do {
 383                 if (i915_gem_wait_for_idle(dev_priv, 0) == 0 &&
 384                     shrinker_lock(dev_priv, unlock))
 385                         break;
 386
 387                 schedule_timeout_killable(1);
 388                 if (fatal_signal_pending(current))
 389                         return false;
 390
 391                 if (time_after(jiffies, timeout)) {
 392                         pr_err("Unable to lock GPU to purge memory.\n");
 393                         return false;
 394                 }
 395         } while (1);
 396
 397         return true;
 398 }
 399
 400 static int
 401 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 402 {
 403         struct drm_i915_private *dev_priv =
 404                 container_of(nb, struct drm_i915_private, mm.oom_notifier);
 405         struct drm_i915_gem_object *obj;
 406         unsigned long unevictable, bound, unbound, freed_pages;
 407
 408         freed_pages = i915_gem_shrink_all(dev_priv);
 409
 410         /* Because we may be allocating inside our own driver, we cannot
 411          * assert that there are no objects with pinned pages that are not
 412          * being pointed to by hardware.
 413          */
 414         unbound = bound = unevictable = 0;
 415         spin_lock(&dev_priv->mm.obj_lock);
 416         list_for_each_entry(obj, &dev_priv->mm.unbound_list, mm.link) {
 417                 if (!can_release_pages(obj))
 418                         unevictable += obj->base.size >> PAGE_SHIFT;
 419                 else
 420                         unbound += obj->base.size >> PAGE_SHIFT;
 421         }
 422         list_for_each_entry(obj, &dev_priv->mm.bound_list, mm.link) {
 423                 if (!can_release_pages(obj))
 424                         unevictable += obj->base.size >> PAGE_SHIFT;
 425                 else
 426                         bound += obj->base.size >> PAGE_SHIFT;
 427         }
 428         spin_unlock(&dev_priv->mm.obj_lock);
 429
 430         if (freed_pages || unbound || bound)
 431                 pr_info("Purging GPU memory, %lu pages freed, "
 432                         "%lu pages still pinned.\n",
 433                         freed_pages, unevictable);
 434         if (unbound || bound)
 435                 pr_err("%lu and %lu pages still available in the "
 436                        "bound and unbound GPU page lists.\n",
 437                        bound, unbound);
 438
 439         *(unsigned long *)ptr += freed_pages;
 440         return NOTIFY_DONE;
 441 }
 442
 443 static int
 444 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
 445 {
 446         struct drm_i915_private *dev_priv =
 447                 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
 448         struct i915_vma *vma, *next;
 449         unsigned long freed_pages = 0;
 450         bool unlock;
 451         int ret;
 452
 453         if (!shrinker_lock_uninterruptible(dev_priv, &unlock, 5000))
 454                 return NOTIFY_DONE;
 455
 456         /* Force everything onto the inactive lists */
 457         ret = i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED);
 458         if (ret)
 459                 goto out;
 460
 461         intel_runtime_pm_get(dev_priv);
 462         freed_pages += i915_gem_shrink(dev_priv, -1UL, NULL,
 463                                        I915_SHRINK_BOUND |
 464                                        I915_SHRINK_UNBOUND |
 465                                        I915_SHRINK_ACTIVE |
 466                                        I915_SHRINK_VMAPS);
 467         intel_runtime_pm_put(dev_priv);
 468
 469         /* We also want to clear any cached iomaps as they wrap vmap */
 470         list_for_each_entry_safe(vma, next,
 471                                  &dev_priv->ggtt.base.inactive_list, vm_link) {
 472                 unsigned long count = vma->node.size >> PAGE_SHIFT;
 473                 if (vma->iomap && i915_vma_unbind(vma) == 0)
 474                         freed_pages += count;
 475         }
 476
 477 out:
 478         shrinker_unlock(dev_priv, unlock);
 479
 480         *(unsigned long *)ptr += freed_pages;
 481         return NOTIFY_DONE;
 482 }
 483 #endif
 484
 485 /**
 486  * i915_gem_shrinker_init - Initialize i915 shrinker
 487  * @dev_priv: i915 device
 488  *
 489  * This function registers and sets up the i915 shrinker and OOM handler.
 490  */
 491 void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
 492 {
 493         dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
 494         dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
 495         dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
 496 #if 0
 497         WARN_ON(register_shrinker(&dev_priv->mm.shrinker));
 498
 499         dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 500         WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));
 501
 502         dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
 503         WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 504 #endif
 505 }
 506
 507 /**
 508  * i915_gem_shrinker_cleanup - Clean up i915 shrinker
 509  * @dev_priv: i915 device
 510  *
 511  * This function unregisters the i915 shrinker and OOM handler.
 512  */
 513 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
 514 {
 515 #if 0
 516         WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 517         WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 518         unregister_shrinker(&dev_priv->mm.shrinker);
 519 #endif
 520 }