2 * Copyright © 2008-2015 Intel Corporation
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25 #include <linux/oom.h>
26 #include <linux/sched/mm.h>
27 #include <linux/shmem_fs.h>
28 #include <linux/slab.h>
29 #include <linux/swap.h>
30 #include <linux/pci.h>
31 #include <linux/dma-buf.h>
32 #include <linux/vmalloc.h>
34 #include <drm/i915_drm.h>
37 #include "i915_trace.h"
39 static bool shrinker_lock(struct drm_i915_private *i915, bool *unlock)
41 switch (mutex_trylock_recursive(&i915->drm.struct_mutex)) {
42 case MUTEX_TRYLOCK_RECURSIVE:
46 case MUTEX_TRYLOCK_FAILED:
51 if (mutex_trylock(&i915->drm.struct_mutex)) {
55 } while (!need_resched());
59 case MUTEX_TRYLOCK_SUCCESS:
67 static void shrinker_unlock(struct drm_i915_private *i915, bool unlock)
72 mutex_unlock(&i915->drm.struct_mutex);
75 static bool swap_available(void)
77 return get_nr_swap_pages() > 0;
80 static bool can_release_pages(struct drm_i915_gem_object *obj)
82 /* Consider only shrinkable ojects. */
83 if (!i915_gem_object_is_shrinkable(obj))
86 /* Only report true if by unbinding the object and putting its pages
87 * we can actually make forward progress towards freeing physical
90 * If the pages are pinned for any other reason than being bound
91 * to the GPU, simply unbinding from the GPU is not going to succeed
92 * in releasing our pin count on the pages themselves.
94 if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count)
97 /* If any vma are "permanently" pinned, it will prevent us from
98 * reclaiming the obj->mm.pages. We only allow scanout objects to claim
99 * a permanent pin, along with a few others like the context objects.
100 * To simplify the scan, and to avoid walking the list of vma under the
101 * object, we just check the count of its permanently pinned.
103 if (READ_ONCE(obj->pin_global))
106 /* We can only return physical pages to the system if we can either
107 * discard the contents (because the user has marked them as being
108 * purgeable) or if we can move their contents out to swap.
110 return swap_available() || obj->mm.madv == I915_MADV_DONTNEED;
113 static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
115 if (i915_gem_object_unbind(obj) == 0)
116 __i915_gem_object_put_pages(obj, I915_MM_SHRINKER);
117 return !i915_gem_object_has_pages(obj);
121 * i915_gem_shrink - Shrink buffer object caches
123 * @target: amount of memory to make available, in pages
124 * @nr_scanned: optional output for number of pages scanned (incremental)
125 * @flags: control flags for selecting cache types
127 * This function is the main interface to the shrinker. It will try to release
128 * up to @target pages of main memory backing storage from buffer objects.
129 * Selection of the specific caches can be done with @flags. This is e.g. useful
130 * when purgeable objects should be removed from caches preferentially.
132 * Note that it's not guaranteed that released amount is actually available as
133 * free system memory - the pages might still be in-used to due to other reasons
134 * (like cpu mmaps) or the mm core has reused them before we could grab them.
135 * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
136 * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
138 * Also note that any kind of pinning (both per-vma address space pins and
139 * backing storage pins at the buffer object level) result in the shrinker code
140 * having to skip the object.
143 * The number of pages of backing storage actually released.
146 i915_gem_shrink(struct drm_i915_private *i915,
147 unsigned long target,
148 unsigned long *nr_scanned,
152 struct list_head *list;
155 { &i915->mm.unbound_list, I915_SHRINK_UNBOUND },
156 { &i915->mm.bound_list, I915_SHRINK_BOUND },
159 unsigned long count = 0;
160 unsigned long scanned = 0;
163 if (!shrinker_lock(i915, &unlock))
167 * When shrinking the active list, also consider active contexts.
168 * Active contexts are pinned until they are retired, and so can
169 * not be simply unbound to retire and unpin their pages. To shrink
170 * the contexts, we must wait until the gpu is idle.
172 * We don't care about errors here; if we cannot wait upon the GPU,
173 * we will free as much as we can and hope to get a second chance.
175 if (flags & I915_SHRINK_ACTIVE)
176 i915_gem_wait_for_idle(i915,
178 MAX_SCHEDULE_TIMEOUT);
180 trace_i915_gem_shrink(i915, target, flags);
181 i915_retire_requests(i915);
184 * Unbinding of objects will require HW access; Let us not wake the
185 * device just to recover a little memory. If absolutely necessary,
186 * we will force the wake during oom-notifier.
188 if ((flags & I915_SHRINK_BOUND) &&
189 !intel_runtime_pm_get_if_in_use(i915))
190 flags &= ~I915_SHRINK_BOUND;
193 * As we may completely rewrite the (un)bound list whilst unbinding
194 * (due to retiring requests) we have to strictly process only
195 * one element of the list at the time, and recheck the list
196 * on every iteration.
198 * In particular, we must hold a reference whilst removing the
199 * object as we may end up waiting for and/or retiring the objects.
200 * This might release the final reference (held by the active list)
201 * and result in the object being freed from under us. This is
202 * similar to the precautions the eviction code must take whilst
205 * Also note that although these lists do not hold a reference to
206 * the object we can safely grab one here: The final object
207 * unreferencing and the bound_list are both protected by the
208 * dev->struct_mutex and so we won't ever be able to observe an
209 * object on the bound_list with a reference count equals 0.
211 for (phase = phases; phase->list; phase++) {
212 struct list_head still_in_list;
213 struct drm_i915_gem_object *obj;
215 if ((flags & phase->bit) == 0)
218 INIT_LIST_HEAD(&still_in_list);
221 * We serialize our access to unreferenced objects through
222 * the use of the struct_mutex. While the objects are not
223 * yet freed (due to RCU then a workqueue) we still want
224 * to be able to shrink their pages, so they remain on
225 * the unbound/bound list until actually freed.
227 spin_lock(&i915->mm.obj_lock);
228 while (count < target &&
229 (obj = list_first_entry_or_null(phase->list,
232 list_move_tail(&obj->mm.link, &still_in_list);
234 if (flags & I915_SHRINK_PURGEABLE &&
235 obj->mm.madv != I915_MADV_DONTNEED)
238 if (flags & I915_SHRINK_VMAPS &&
239 !is_vmalloc_addr(obj->mm.mapping))
242 if (!(flags & I915_SHRINK_ACTIVE) &&
243 (i915_gem_object_is_active(obj) ||
244 i915_gem_object_is_framebuffer(obj)))
247 if (!can_release_pages(obj))
250 spin_unlock(&i915->mm.obj_lock);
252 if (unsafe_drop_pages(obj)) {
253 /* May arrive from get_pages on another bo */
254 mutex_lock_nested(&obj->mm.lock,
256 if (!i915_gem_object_has_pages(obj)) {
257 __i915_gem_object_invalidate(obj);
258 count += obj->base.size >> PAGE_SHIFT;
260 mutex_unlock(&obj->mm.lock);
262 scanned += obj->base.size >> PAGE_SHIFT;
264 spin_lock(&i915->mm.obj_lock);
266 list_splice_tail(&still_in_list, phase->list);
267 spin_unlock(&i915->mm.obj_lock);
270 if (flags & I915_SHRINK_BOUND)
271 intel_runtime_pm_put(i915);
273 i915_retire_requests(i915);
275 shrinker_unlock(i915, unlock);
278 *nr_scanned += scanned;
283 * i915_gem_shrink_all - Shrink buffer object caches completely
286 * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
287 * caches completely. It also first waits for and retires all outstanding
288 * requests to also be able to release backing storage for active objects.
290 * This should only be used in code to intentionally quiescent the gpu or as a
291 * last-ditch effort when memory seems to have run out.
294 * The number of pages of backing storage actually released.
296 unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
300 intel_runtime_pm_get(i915);
301 freed = i915_gem_shrink(i915, -1UL, NULL,
303 I915_SHRINK_UNBOUND |
305 intel_runtime_pm_put(i915);
311 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
313 struct drm_i915_private *i915 =
314 container_of(shrinker, struct drm_i915_private, mm.shrinker);
315 struct drm_i915_gem_object *obj;
316 unsigned long num_objects = 0;
317 unsigned long count = 0;
319 spin_lock(&i915->mm.obj_lock);
320 list_for_each_entry(obj, &i915->mm.unbound_list, mm.link)
321 if (can_release_pages(obj)) {
322 count += obj->base.size >> PAGE_SHIFT;
326 list_for_each_entry(obj, &i915->mm.bound_list, mm.link)
327 if (!i915_gem_object_is_active(obj) && can_release_pages(obj)) {
328 count += obj->base.size >> PAGE_SHIFT;
331 spin_unlock(&i915->mm.obj_lock);
333 /* Update our preferred vmscan batch size for the next pass.
334 * Our rough guess for an effective batch size is roughly 2
335 * available GEM objects worth of pages. That is we don't want
336 * the shrinker to fire, until it is worth the cost of freeing an
340 unsigned long avg = 2 * count / num_objects;
342 i915->mm.shrinker.batch =
343 max((i915->mm.shrinker.batch + avg) >> 1,
344 128ul /* default SHRINK_BATCH */);
351 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
353 struct drm_i915_private *i915 =
354 container_of(shrinker, struct drm_i915_private, mm.shrinker);
360 if (!shrinker_lock(i915, &unlock))
363 freed = i915_gem_shrink(i915,
367 I915_SHRINK_UNBOUND |
368 I915_SHRINK_PURGEABLE);
369 if (sc->nr_scanned < sc->nr_to_scan)
370 freed += i915_gem_shrink(i915,
371 sc->nr_to_scan - sc->nr_scanned,
374 I915_SHRINK_UNBOUND);
375 if (sc->nr_scanned < sc->nr_to_scan && current_is_kswapd()) {
376 intel_runtime_pm_get(i915);
377 freed += i915_gem_shrink(i915,
378 sc->nr_to_scan - sc->nr_scanned,
382 I915_SHRINK_UNBOUND);
383 intel_runtime_pm_put(i915);
386 shrinker_unlock(i915, unlock);
388 return sc->nr_scanned ? freed : SHRINK_STOP;
392 shrinker_lock_uninterruptible(struct drm_i915_private *i915, bool *unlock,
395 unsigned long timeout = jiffies + msecs_to_jiffies_timeout(timeout_ms);
398 if (i915_gem_wait_for_idle(i915,
399 0, MAX_SCHEDULE_TIMEOUT) == 0 &&
400 shrinker_lock(i915, unlock))
403 schedule_timeout_killable(1);
404 if (fatal_signal_pending(current))
407 if (time_after(jiffies, timeout)) {
408 pr_err("Unable to lock GPU to purge memory.\n");
417 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
419 struct drm_i915_private *i915 =
420 container_of(nb, struct drm_i915_private, mm.oom_notifier);
421 struct drm_i915_gem_object *obj;
422 unsigned long unevictable, bound, unbound, freed_pages;
424 freed_pages = i915_gem_shrink_all(i915);
426 /* Because we may be allocating inside our own driver, we cannot
427 * assert that there are no objects with pinned pages that are not
428 * being pointed to by hardware.
430 unbound = bound = unevictable = 0;
431 spin_lock(&i915->mm.obj_lock);
432 list_for_each_entry(obj, &i915->mm.unbound_list, mm.link) {
433 if (!can_release_pages(obj))
434 unevictable += obj->base.size >> PAGE_SHIFT;
436 unbound += obj->base.size >> PAGE_SHIFT;
438 list_for_each_entry(obj, &i915->mm.bound_list, mm.link) {
439 if (!can_release_pages(obj))
440 unevictable += obj->base.size >> PAGE_SHIFT;
442 bound += obj->base.size >> PAGE_SHIFT;
444 spin_unlock(&i915->mm.obj_lock);
446 if (freed_pages || unbound || bound)
447 pr_info("Purging GPU memory, %lu pages freed, "
448 "%lu pages still pinned.\n",
449 freed_pages, unevictable);
450 if (unbound || bound)
451 pr_err("%lu and %lu pages still available in the "
452 "bound and unbound GPU page lists.\n",
455 *(unsigned long *)ptr += freed_pages;
460 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
462 struct drm_i915_private *i915 =
463 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
464 struct i915_vma *vma, *next;
465 unsigned long freed_pages = 0;
469 if (!shrinker_lock_uninterruptible(i915, &unlock, 5000))
472 /* Force everything onto the inactive lists */
473 ret = i915_gem_wait_for_idle(i915,
475 MAX_SCHEDULE_TIMEOUT);
479 intel_runtime_pm_get(i915);
480 freed_pages += i915_gem_shrink(i915, -1UL, NULL,
482 I915_SHRINK_UNBOUND |
485 intel_runtime_pm_put(i915);
487 /* We also want to clear any cached iomaps as they wrap vmap */
488 list_for_each_entry_safe(vma, next,
489 &i915->ggtt.vm.inactive_list, vm_link) {
490 unsigned long count = vma->node.size >> PAGE_SHIFT;
491 if (vma->iomap && i915_vma_unbind(vma) == 0)
492 freed_pages += count;
496 shrinker_unlock(i915, unlock);
498 *(unsigned long *)ptr += freed_pages;
503 * i915_gem_shrinker_register - Register the i915 shrinker
506 * This function registers and sets up the i915 shrinker and OOM handler.
508 void i915_gem_shrinker_register(struct drm_i915_private *i915)
510 i915->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
511 i915->mm.shrinker.count_objects = i915_gem_shrinker_count;
512 i915->mm.shrinker.seeks = DEFAULT_SEEKS;
513 i915->mm.shrinker.batch = 4096;
514 WARN_ON(register_shrinker(&i915->mm.shrinker));
516 i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
517 WARN_ON(register_oom_notifier(&i915->mm.oom_notifier));
519 i915->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
520 WARN_ON(register_vmap_purge_notifier(&i915->mm.vmap_notifier));
524 * i915_gem_shrinker_unregister - Unregisters the i915 shrinker
527 * This function unregisters the i915 shrinker and OOM handler.
529 void i915_gem_shrinker_unregister(struct drm_i915_private *i915)
531 WARN_ON(unregister_vmap_purge_notifier(&i915->mm.vmap_notifier));
532 WARN_ON(unregister_oom_notifier(&i915->mm.oom_notifier));
533 unregister_shrinker(&i915->mm.shrinker);
536 void i915_gem_shrinker_taints_mutex(struct mutex *mutex)
538 if (!IS_ENABLED(CONFIG_LOCKDEP))
541 fs_reclaim_acquire(GFP_KERNEL);
544 fs_reclaim_release(GFP_KERNEL);