locking/lockdep: Remove unused @nested argument from lock_release()
[sfrench/cifs-2.6.git] / drivers / gpu / drm / i915 / gem / i915_gem_shrinker.c
1 /*
2  * SPDX-License-Identifier: MIT
3  *
4  * Copyright © 2008-2015 Intel Corporation
5  */
6
7 #include <linux/oom.h>
8 #include <linux/sched/mm.h>
9 #include <linux/shmem_fs.h>
10 #include <linux/slab.h>
11 #include <linux/swap.h>
12 #include <linux/pci.h>
13 #include <linux/dma-buf.h>
14 #include <linux/vmalloc.h>
15 #include <drm/i915_drm.h>
16
17 #include "i915_trace.h"
18
19 static bool shrinker_lock(struct drm_i915_private *i915,
20                           unsigned int flags,
21                           bool *unlock)
22 {
23         struct mutex *m = &i915->drm.struct_mutex;
24
25         switch (mutex_trylock_recursive(m)) {
26         case MUTEX_TRYLOCK_RECURSIVE:
27                 *unlock = false;
28                 return true;
29
30         case MUTEX_TRYLOCK_FAILED:
31                 *unlock = false;
32                 if (flags & I915_SHRINK_ACTIVE &&
33                     mutex_lock_killable_nested(m, I915_MM_SHRINKER) == 0)
34                         *unlock = true;
35                 return *unlock;
36
37         case MUTEX_TRYLOCK_SUCCESS:
38                 *unlock = true;
39                 return true;
40         }
41
42         BUG();
43 }
44
45 static void shrinker_unlock(struct drm_i915_private *i915, bool unlock)
46 {
47         if (!unlock)
48                 return;
49
50         mutex_unlock(&i915->drm.struct_mutex);
51 }
52
53 static bool swap_available(void)
54 {
55         return get_nr_swap_pages() > 0;
56 }
57
58 static bool can_release_pages(struct drm_i915_gem_object *obj)
59 {
60         /* Consider only shrinkable ojects. */
61         if (!i915_gem_object_is_shrinkable(obj))
62                 return false;
63
64         /* Only report true if by unbinding the object and putting its pages
65          * we can actually make forward progress towards freeing physical
66          * pages.
67          *
68          * If the pages are pinned for any other reason than being bound
69          * to the GPU, simply unbinding from the GPU is not going to succeed
70          * in releasing our pin count on the pages themselves.
71          */
72         if (atomic_read(&obj->mm.pages_pin_count) > atomic_read(&obj->bind_count))
73                 return false;
74
75         /* If any vma are "permanently" pinned, it will prevent us from
76          * reclaiming the obj->mm.pages. We only allow scanout objects to claim
77          * a permanent pin, along with a few others like the context objects.
78          * To simplify the scan, and to avoid walking the list of vma under the
79          * object, we just check the count of its permanently pinned.
80          */
81         if (READ_ONCE(obj->pin_global))
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->mm.madv == I915_MADV_DONTNEED;
89 }
90
91 static bool unsafe_drop_pages(struct drm_i915_gem_object *obj,
92                               unsigned long shrink)
93 {
94         unsigned long flags;
95
96         flags = 0;
97         if (shrink & I915_SHRINK_ACTIVE)
98                 flags = I915_GEM_OBJECT_UNBIND_ACTIVE;
99
100         if (i915_gem_object_unbind(obj, flags) == 0)
101                 __i915_gem_object_put_pages(obj, I915_MM_SHRINKER);
102
103         return !i915_gem_object_has_pages(obj);
104 }
105
106 static void try_to_writeback(struct drm_i915_gem_object *obj,
107                              unsigned int flags)
108 {
109         switch (obj->mm.madv) {
110         case I915_MADV_DONTNEED:
111                 i915_gem_object_truncate(obj);
112         case __I915_MADV_PURGED:
113                 return;
114         }
115
116         if (flags & I915_SHRINK_WRITEBACK)
117                 i915_gem_object_writeback(obj);
118 }
119
120 /**
121  * i915_gem_shrink - Shrink buffer object caches
122  * @i915: i915 device
123  * @target: amount of memory to make available, in pages
124  * @nr_scanned: optional output for number of pages scanned (incremental)
125  * @shrink: control flags for selecting cache types
126  *
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.
131  *
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().
137  *
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.
141  *
142  * Returns:
143  * The number of pages of backing storage actually released.
144  */
145 unsigned long
146 i915_gem_shrink(struct drm_i915_private *i915,
147                 unsigned long target,
148                 unsigned long *nr_scanned,
149                 unsigned int shrink)
150 {
151         const struct {
152                 struct list_head *list;
153                 unsigned int bit;
154         } phases[] = {
155                 { &i915->mm.purge_list, ~0u },
156                 {
157                         &i915->mm.shrink_list,
158                         I915_SHRINK_BOUND | I915_SHRINK_UNBOUND
159                 },
160                 { NULL, 0 },
161         }, *phase;
162         intel_wakeref_t wakeref = 0;
163         unsigned long count = 0;
164         unsigned long scanned = 0;
165         bool unlock;
166
167         if (!shrinker_lock(i915, shrink, &unlock))
168                 return 0;
169
170         /*
171          * When shrinking the active list, we should also consider active
172          * contexts. Active contexts are pinned until they are retired, and
173          * so can not be simply unbound to retire and unpin their pages. To
174          * shrink the contexts, we must wait until the gpu is idle and
175          * completed its switch to the kernel context. In short, we do
176          * not have a good mechanism for idling a specific context.
177          */
178
179         trace_i915_gem_shrink(i915, target, shrink);
180
181         /*
182          * Unbinding of objects will require HW access; Let us not wake the
183          * device just to recover a little memory. If absolutely necessary,
184          * we will force the wake during oom-notifier.
185          */
186         if (shrink & I915_SHRINK_BOUND) {
187                 wakeref = intel_runtime_pm_get_if_in_use(&i915->runtime_pm);
188                 if (!wakeref)
189                         shrink &= ~I915_SHRINK_BOUND;
190         }
191
192         /*
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.
197          *
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
203          * removing objects.
204          *
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.
210          */
211         for (phase = phases; phase->list; phase++) {
212                 struct list_head still_in_list;
213                 struct drm_i915_gem_object *obj;
214                 unsigned long flags;
215
216                 if ((shrink & phase->bit) == 0)
217                         continue;
218
219                 INIT_LIST_HEAD(&still_in_list);
220
221                 /*
222                  * We serialize our access to unreferenced objects through
223                  * the use of the struct_mutex. While the objects are not
224                  * yet freed (due to RCU then a workqueue) we still want
225                  * to be able to shrink their pages, so they remain on
226                  * the unbound/bound list until actually freed.
227                  */
228                 spin_lock_irqsave(&i915->mm.obj_lock, flags);
229                 while (count < target &&
230                        (obj = list_first_entry_or_null(phase->list,
231                                                        typeof(*obj),
232                                                        mm.link))) {
233                         list_move_tail(&obj->mm.link, &still_in_list);
234
235                         if (shrink & I915_SHRINK_VMAPS &&
236                             !is_vmalloc_addr(obj->mm.mapping))
237                                 continue;
238
239                         if (!(shrink & I915_SHRINK_ACTIVE) &&
240                             i915_gem_object_is_framebuffer(obj))
241                                 continue;
242
243                         if (!(shrink & I915_SHRINK_BOUND) &&
244                             atomic_read(&obj->bind_count))
245                                 continue;
246
247                         if (!can_release_pages(obj))
248                                 continue;
249
250                         if (!kref_get_unless_zero(&obj->base.refcount))
251                                 continue;
252
253                         spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
254
255                         if (unsafe_drop_pages(obj, shrink)) {
256                                 /* May arrive from get_pages on another bo */
257                                 mutex_lock_nested(&obj->mm.lock,
258                                                   I915_MM_SHRINKER);
259                                 if (!i915_gem_object_has_pages(obj)) {
260                                         try_to_writeback(obj, shrink);
261                                         count += obj->base.size >> PAGE_SHIFT;
262                                 }
263                                 mutex_unlock(&obj->mm.lock);
264                         }
265
266                         scanned += obj->base.size >> PAGE_SHIFT;
267                         i915_gem_object_put(obj);
268
269                         spin_lock_irqsave(&i915->mm.obj_lock, flags);
270                 }
271                 list_splice_tail(&still_in_list, phase->list);
272                 spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
273         }
274
275         if (shrink & I915_SHRINK_BOUND)
276                 intel_runtime_pm_put(&i915->runtime_pm, wakeref);
277
278         shrinker_unlock(i915, unlock);
279
280         if (nr_scanned)
281                 *nr_scanned += scanned;
282         return count;
283 }
284
285 /**
286  * i915_gem_shrink_all - Shrink buffer object caches completely
287  * @i915: i915 device
288  *
289  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
290  * caches completely. It also first waits for and retires all outstanding
291  * requests to also be able to release backing storage for active objects.
292  *
293  * This should only be used in code to intentionally quiescent the gpu or as a
294  * last-ditch effort when memory seems to have run out.
295  *
296  * Returns:
297  * The number of pages of backing storage actually released.
298  */
299 unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
300 {
301         intel_wakeref_t wakeref;
302         unsigned long freed = 0;
303
304         with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
305                 freed = i915_gem_shrink(i915, -1UL, NULL,
306                                         I915_SHRINK_BOUND |
307                                         I915_SHRINK_UNBOUND |
308                                         I915_SHRINK_ACTIVE);
309         }
310
311         return freed;
312 }
313
314 static unsigned long
315 i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
316 {
317         struct drm_i915_private *i915 =
318                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
319         unsigned long num_objects;
320         unsigned long count;
321
322         count = READ_ONCE(i915->mm.shrink_memory) >> PAGE_SHIFT;
323         num_objects = READ_ONCE(i915->mm.shrink_count);
324
325         /*
326          * Update our preferred vmscan batch size for the next pass.
327          * Our rough guess for an effective batch size is roughly 2
328          * available GEM objects worth of pages. That is we don't want
329          * the shrinker to fire, until it is worth the cost of freeing an
330          * entire GEM object.
331          */
332         if (num_objects) {
333                 unsigned long avg = 2 * count / num_objects;
334
335                 i915->mm.shrinker.batch =
336                         max((i915->mm.shrinker.batch + avg) >> 1,
337                             128ul /* default SHRINK_BATCH */);
338         }
339
340         return count;
341 }
342
343 static unsigned long
344 i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
345 {
346         struct drm_i915_private *i915 =
347                 container_of(shrinker, struct drm_i915_private, mm.shrinker);
348         unsigned long freed;
349         bool unlock;
350
351         sc->nr_scanned = 0;
352
353         if (!shrinker_lock(i915, 0, &unlock))
354                 return SHRINK_STOP;
355
356         freed = i915_gem_shrink(i915,
357                                 sc->nr_to_scan,
358                                 &sc->nr_scanned,
359                                 I915_SHRINK_BOUND |
360                                 I915_SHRINK_UNBOUND |
361                                 I915_SHRINK_WRITEBACK);
362         if (sc->nr_scanned < sc->nr_to_scan && current_is_kswapd()) {
363                 intel_wakeref_t wakeref;
364
365                 with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
366                         freed += i915_gem_shrink(i915,
367                                                  sc->nr_to_scan - sc->nr_scanned,
368                                                  &sc->nr_scanned,
369                                                  I915_SHRINK_ACTIVE |
370                                                  I915_SHRINK_BOUND |
371                                                  I915_SHRINK_UNBOUND |
372                                                  I915_SHRINK_WRITEBACK);
373                 }
374         }
375
376         shrinker_unlock(i915, unlock);
377
378         return sc->nr_scanned ? freed : SHRINK_STOP;
379 }
380
381 static int
382 i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
383 {
384         struct drm_i915_private *i915 =
385                 container_of(nb, struct drm_i915_private, mm.oom_notifier);
386         struct drm_i915_gem_object *obj;
387         unsigned long unevictable, available, freed_pages;
388         intel_wakeref_t wakeref;
389         unsigned long flags;
390
391         freed_pages = 0;
392         with_intel_runtime_pm(&i915->runtime_pm, wakeref)
393                 freed_pages += i915_gem_shrink(i915, -1UL, NULL,
394                                                I915_SHRINK_BOUND |
395                                                I915_SHRINK_UNBOUND |
396                                                I915_SHRINK_WRITEBACK);
397
398         /* Because we may be allocating inside our own driver, we cannot
399          * assert that there are no objects with pinned pages that are not
400          * being pointed to by hardware.
401          */
402         available = unevictable = 0;
403         spin_lock_irqsave(&i915->mm.obj_lock, flags);
404         list_for_each_entry(obj, &i915->mm.shrink_list, mm.link) {
405                 if (!can_release_pages(obj))
406                         unevictable += obj->base.size >> PAGE_SHIFT;
407                 else
408                         available += obj->base.size >> PAGE_SHIFT;
409         }
410         spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
411
412         if (freed_pages || available)
413                 pr_info("Purging GPU memory, %lu pages freed, "
414                         "%lu pages still pinned, %lu pages left available.\n",
415                         freed_pages, unevictable, available);
416
417         *(unsigned long *)ptr += freed_pages;
418         return NOTIFY_DONE;
419 }
420
421 static int
422 i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
423 {
424         struct drm_i915_private *i915 =
425                 container_of(nb, struct drm_i915_private, mm.vmap_notifier);
426         struct i915_vma *vma, *next;
427         unsigned long freed_pages = 0;
428         intel_wakeref_t wakeref;
429         bool unlock;
430
431         if (!shrinker_lock(i915, 0, &unlock))
432                 return NOTIFY_DONE;
433
434         with_intel_runtime_pm(&i915->runtime_pm, wakeref)
435                 freed_pages += i915_gem_shrink(i915, -1UL, NULL,
436                                                I915_SHRINK_BOUND |
437                                                I915_SHRINK_UNBOUND |
438                                                I915_SHRINK_VMAPS);
439
440         /* We also want to clear any cached iomaps as they wrap vmap */
441         mutex_lock(&i915->ggtt.vm.mutex);
442         list_for_each_entry_safe(vma, next,
443                                  &i915->ggtt.vm.bound_list, vm_link) {
444                 unsigned long count = vma->node.size >> PAGE_SHIFT;
445
446                 if (!vma->iomap || i915_vma_is_active(vma))
447                         continue;
448
449                 mutex_unlock(&i915->ggtt.vm.mutex);
450                 if (i915_vma_unbind(vma) == 0)
451                         freed_pages += count;
452                 mutex_lock(&i915->ggtt.vm.mutex);
453         }
454         mutex_unlock(&i915->ggtt.vm.mutex);
455
456         shrinker_unlock(i915, unlock);
457
458         *(unsigned long *)ptr += freed_pages;
459         return NOTIFY_DONE;
460 }
461
462 void i915_gem_driver_register__shrinker(struct drm_i915_private *i915)
463 {
464         i915->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
465         i915->mm.shrinker.count_objects = i915_gem_shrinker_count;
466         i915->mm.shrinker.seeks = DEFAULT_SEEKS;
467         i915->mm.shrinker.batch = 4096;
468         WARN_ON(register_shrinker(&i915->mm.shrinker));
469
470         i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
471         WARN_ON(register_oom_notifier(&i915->mm.oom_notifier));
472
473         i915->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
474         WARN_ON(register_vmap_purge_notifier(&i915->mm.vmap_notifier));
475 }
476
477 void i915_gem_driver_unregister__shrinker(struct drm_i915_private *i915)
478 {
479         WARN_ON(unregister_vmap_purge_notifier(&i915->mm.vmap_notifier));
480         WARN_ON(unregister_oom_notifier(&i915->mm.oom_notifier));
481         unregister_shrinker(&i915->mm.shrinker);
482 }
483
484 void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
485                                     struct mutex *mutex)
486 {
487         bool unlock = false;
488
489         if (!IS_ENABLED(CONFIG_LOCKDEP))
490                 return;
491
492         if (!lockdep_is_held_type(&i915->drm.struct_mutex, -1)) {
493                 mutex_acquire(&i915->drm.struct_mutex.dep_map,
494                               I915_MM_NORMAL, 0, _RET_IP_);
495                 unlock = true;
496         }
497
498         fs_reclaim_acquire(GFP_KERNEL);
499
500         /*
501          * As we invariably rely on the struct_mutex within the shrinker,
502          * but have a complicated recursion dance, taint all the mutexes used
503          * within the shrinker with the struct_mutex. For completeness, we
504          * taint with all subclass of struct_mutex, even though we should
505          * only need tainting by I915_MM_NORMAL to catch possible ABBA
506          * deadlocks from using struct_mutex inside @mutex.
507          */
508         mutex_acquire(&i915->drm.struct_mutex.dep_map,
509                       I915_MM_SHRINKER, 0, _RET_IP_);
510
511         mutex_acquire(&mutex->dep_map, 0, 0, _RET_IP_);
512         mutex_release(&mutex->dep_map, _RET_IP_);
513
514         mutex_release(&i915->drm.struct_mutex.dep_map, _RET_IP_);
515
516         fs_reclaim_release(GFP_KERNEL);
517
518         if (unlock)
519                 mutex_release(&i915->drm.struct_mutex.dep_map, _RET_IP_);
520 }
521
522 #define obj_to_i915(obj__) to_i915((obj__)->base.dev)
523
524 void i915_gem_object_make_unshrinkable(struct drm_i915_gem_object *obj)
525 {
526         /*
527          * We can only be called while the pages are pinned or when
528          * the pages are released. If pinned, we should only be called
529          * from a single caller under controlled conditions; and on release
530          * only one caller may release us. Neither the two may cross.
531          */
532         if (!list_empty(&obj->mm.link)) { /* pinned by caller */
533                 struct drm_i915_private *i915 = obj_to_i915(obj);
534                 unsigned long flags;
535
536                 spin_lock_irqsave(&i915->mm.obj_lock, flags);
537                 GEM_BUG_ON(list_empty(&obj->mm.link));
538
539                 list_del_init(&obj->mm.link);
540                 i915->mm.shrink_count--;
541                 i915->mm.shrink_memory -= obj->base.size;
542
543                 spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
544         }
545 }
546
547 static void __i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj,
548                                               struct list_head *head)
549 {
550         GEM_BUG_ON(!i915_gem_object_has_pages(obj));
551         GEM_BUG_ON(!list_empty(&obj->mm.link));
552
553         if (i915_gem_object_is_shrinkable(obj)) {
554                 struct drm_i915_private *i915 = obj_to_i915(obj);
555                 unsigned long flags;
556
557                 spin_lock_irqsave(&i915->mm.obj_lock, flags);
558                 GEM_BUG_ON(!kref_read(&obj->base.refcount));
559
560                 list_add_tail(&obj->mm.link, head);
561                 i915->mm.shrink_count++;
562                 i915->mm.shrink_memory += obj->base.size;
563
564                 spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
565         }
566 }
567
568 void i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj)
569 {
570         __i915_gem_object_make_shrinkable(obj,
571                                           &obj_to_i915(obj)->mm.shrink_list);
572 }
573
574 void i915_gem_object_make_purgeable(struct drm_i915_gem_object *obj)
575 {
576         __i915_gem_object_make_shrinkable(obj,
577                                           &obj_to_i915(obj)->mm.purge_list);
578 }