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Diffstat (limited to 'drivers/gpu/drm/i915/gem/i915_gem_shrinker.c')
-rw-r--r--drivers/gpu/drm/i915/gem/i915_gem_shrinker.c535
1 files changed, 535 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
new file mode 100644
index 000000000000..3a926a8755c6
--- /dev/null
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
@@ -0,0 +1,535 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2008-2015 Intel Corporation
+ */
+
+#include <linux/oom.h>
+#include <linux/sched/mm.h>
+#include <linux/shmem_fs.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/pci.h>
+#include <linux/dma-buf.h>
+#include <linux/vmalloc.h>
+#include <drm/i915_drm.h>
+
+#include "i915_trace.h"
+
+static bool shrinker_lock(struct drm_i915_private *i915,
+ unsigned int flags,
+ bool *unlock)
+{
+ struct mutex *m = &i915->drm.struct_mutex;
+
+ switch (mutex_trylock_recursive(m)) {
+ case MUTEX_TRYLOCK_RECURSIVE:
+ *unlock = false;
+ return true;
+
+ case MUTEX_TRYLOCK_FAILED:
+ *unlock = false;
+ if (flags & I915_SHRINK_ACTIVE &&
+ mutex_lock_killable_nested(m, I915_MM_SHRINKER) == 0)
+ *unlock = true;
+ return *unlock;
+
+ case MUTEX_TRYLOCK_SUCCESS:
+ *unlock = true;
+ return true;
+ }
+
+ BUG();
+}
+
+static void shrinker_unlock(struct drm_i915_private *i915, bool unlock)
+{
+ if (!unlock)
+ return;
+
+ mutex_unlock(&i915->drm.struct_mutex);
+}
+
+static bool swap_available(void)
+{
+ return get_nr_swap_pages() > 0;
+}
+
+static bool can_release_pages(struct drm_i915_gem_object *obj)
+{
+ /* Consider only shrinkable ojects. */
+ if (!i915_gem_object_is_shrinkable(obj))
+ return false;
+
+ /* Only report true if by unbinding the object and putting its pages
+ * we can actually make forward progress towards freeing physical
+ * pages.
+ *
+ * If the pages are pinned for any other reason than being bound
+ * to the GPU, simply unbinding from the GPU is not going to succeed
+ * in releasing our pin count on the pages themselves.
+ */
+ if (atomic_read(&obj->mm.pages_pin_count) > atomic_read(&obj->bind_count))
+ return false;
+
+ /* If any vma are "permanently" pinned, it will prevent us from
+ * reclaiming the obj->mm.pages. We only allow scanout objects to claim
+ * a permanent pin, along with a few others like the context objects.
+ * To simplify the scan, and to avoid walking the list of vma under the
+ * object, we just check the count of its permanently pinned.
+ */
+ if (READ_ONCE(obj->pin_global))
+ return false;
+
+ /* We can only return physical pages to the system if we can either
+ * discard the contents (because the user has marked them as being
+ * purgeable) or if we can move their contents out to swap.
+ */
+ return swap_available() || obj->mm.madv == I915_MADV_DONTNEED;
+}
+
+static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
+{
+ if (i915_gem_object_unbind(obj) == 0)
+ __i915_gem_object_put_pages(obj, I915_MM_SHRINKER);
+ return !i915_gem_object_has_pages(obj);
+}
+
+static void try_to_writeback(struct drm_i915_gem_object *obj,
+ unsigned int flags)
+{
+ switch (obj->mm.madv) {
+ case I915_MADV_DONTNEED:
+ i915_gem_object_truncate(obj);
+ case __I915_MADV_PURGED:
+ return;
+ }
+
+ if (flags & I915_SHRINK_WRITEBACK)
+ i915_gem_object_writeback(obj);
+}
+
+/**
+ * i915_gem_shrink - Shrink buffer object caches
+ * @i915: i915 device
+ * @target: amount of memory to make available, in pages
+ * @nr_scanned: optional output for number of pages scanned (incremental)
+ * @shrink: control flags for selecting cache types
+ *
+ * This function is the main interface to the shrinker. It will try to release
+ * up to @target pages of main memory backing storage from buffer objects.
+ * Selection of the specific caches can be done with @flags. This is e.g. useful
+ * when purgeable objects should be removed from caches preferentially.
+ *
+ * Note that it's not guaranteed that released amount is actually available as
+ * free system memory - the pages might still be in-used to due to other reasons
+ * (like cpu mmaps) or the mm core has reused them before we could grab them.
+ * Therefore code that needs to explicitly shrink buffer objects caches (e.g. to
+ * avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all().
+ *
+ * Also note that any kind of pinning (both per-vma address space pins and
+ * backing storage pins at the buffer object level) result in the shrinker code
+ * having to skip the object.
+ *
+ * Returns:
+ * The number of pages of backing storage actually released.
+ */
+unsigned long
+i915_gem_shrink(struct drm_i915_private *i915,
+ unsigned long target,
+ unsigned long *nr_scanned,
+ unsigned int shrink)
+{
+ const struct {
+ struct list_head *list;
+ unsigned int bit;
+ } phases[] = {
+ { &i915->mm.purge_list, ~0u },
+ {
+ &i915->mm.shrink_list,
+ I915_SHRINK_BOUND | I915_SHRINK_UNBOUND
+ },
+ { NULL, 0 },
+ }, *phase;
+ intel_wakeref_t wakeref = 0;
+ unsigned long count = 0;
+ unsigned long scanned = 0;
+ bool unlock;
+
+ if (!shrinker_lock(i915, shrink, &unlock))
+ return 0;
+
+ /*
+ * When shrinking the active list, we should also consider active
+ * contexts. Active contexts are pinned until they are retired, and
+ * so can not be simply unbound to retire and unpin their pages. To
+ * shrink the contexts, we must wait until the gpu is idle and
+ * completed its switch to the kernel context. In short, we do
+ * not have a good mechanism for idling a specific context.
+ */
+
+ trace_i915_gem_shrink(i915, target, shrink);
+ i915_retire_requests(i915);
+
+ /*
+ * Unbinding of objects will require HW access; Let us not wake the
+ * device just to recover a little memory. If absolutely necessary,
+ * we will force the wake during oom-notifier.
+ */
+ if (shrink & I915_SHRINK_BOUND) {
+ wakeref = intel_runtime_pm_get_if_in_use(&i915->runtime_pm);
+ if (!wakeref)
+ shrink &= ~I915_SHRINK_BOUND;
+ }
+
+ /*
+ * As we may completely rewrite the (un)bound list whilst unbinding
+ * (due to retiring requests) we have to strictly process only
+ * one element of the list at the time, and recheck the list
+ * on every iteration.
+ *
+ * In particular, we must hold a reference whilst removing the
+ * object as we may end up waiting for and/or retiring the objects.
+ * This might release the final reference (held by the active list)
+ * and result in the object being freed from under us. This is
+ * similar to the precautions the eviction code must take whilst
+ * removing objects.
+ *
+ * Also note that although these lists do not hold a reference to
+ * the object we can safely grab one here: The final object
+ * unreferencing and the bound_list are both protected by the
+ * dev->struct_mutex and so we won't ever be able to observe an
+ * object on the bound_list with a reference count equals 0.
+ */
+ for (phase = phases; phase->list; phase++) {
+ struct list_head still_in_list;
+ struct drm_i915_gem_object *obj;
+ unsigned long flags;
+
+ if ((shrink & phase->bit) == 0)
+ continue;
+
+ INIT_LIST_HEAD(&still_in_list);
+
+ /*
+ * We serialize our access to unreferenced objects through
+ * the use of the struct_mutex. While the objects are not
+ * yet freed (due to RCU then a workqueue) we still want
+ * to be able to shrink their pages, so they remain on
+ * the unbound/bound list until actually freed.
+ */
+ spin_lock_irqsave(&i915->mm.obj_lock, flags);
+ while (count < target &&
+ (obj = list_first_entry_or_null(phase->list,
+ typeof(*obj),
+ mm.link))) {
+ list_move_tail(&obj->mm.link, &still_in_list);
+
+ if (shrink & I915_SHRINK_VMAPS &&
+ !is_vmalloc_addr(obj->mm.mapping))
+ continue;
+
+ if (!(shrink & I915_SHRINK_ACTIVE) &&
+ (i915_gem_object_is_active(obj) ||
+ i915_gem_object_is_framebuffer(obj)))
+ continue;
+
+ if (!(shrink & I915_SHRINK_BOUND) &&
+ atomic_read(&obj->bind_count))
+ continue;
+
+ if (!can_release_pages(obj))
+ continue;
+
+ if (!kref_get_unless_zero(&obj->base.refcount))
+ continue;
+
+ spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
+
+ if (unsafe_drop_pages(obj)) {
+ /* May arrive from get_pages on another bo */
+ mutex_lock_nested(&obj->mm.lock,
+ I915_MM_SHRINKER);
+ if (!i915_gem_object_has_pages(obj)) {
+ try_to_writeback(obj, shrink);
+ count += obj->base.size >> PAGE_SHIFT;
+ }
+ mutex_unlock(&obj->mm.lock);
+ }
+
+ scanned += obj->base.size >> PAGE_SHIFT;
+ i915_gem_object_put(obj);
+
+ spin_lock_irqsave(&i915->mm.obj_lock, flags);
+ }
+ list_splice_tail(&still_in_list, phase->list);
+ spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
+ }
+
+ if (shrink & I915_SHRINK_BOUND)
+ intel_runtime_pm_put(&i915->runtime_pm, wakeref);
+
+ i915_retire_requests(i915);
+
+ shrinker_unlock(i915, unlock);
+
+ if (nr_scanned)
+ *nr_scanned += scanned;
+ return count;
+}
+
+/**
+ * i915_gem_shrink_all - Shrink buffer object caches completely
+ * @i915: i915 device
+ *
+ * This is a simple wraper around i915_gem_shrink() to aggressively shrink all
+ * caches completely. It also first waits for and retires all outstanding
+ * requests to also be able to release backing storage for active objects.
+ *
+ * This should only be used in code to intentionally quiescent the gpu or as a
+ * last-ditch effort when memory seems to have run out.
+ *
+ * Returns:
+ * The number of pages of backing storage actually released.
+ */
+unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
+{
+ intel_wakeref_t wakeref;
+ unsigned long freed = 0;
+
+ with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
+ freed = i915_gem_shrink(i915, -1UL, NULL,
+ I915_SHRINK_BOUND |
+ I915_SHRINK_UNBOUND |
+ I915_SHRINK_ACTIVE);
+ }
+
+ return freed;
+}
+
+static unsigned long
+i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
+{
+ struct drm_i915_private *i915 =
+ container_of(shrinker, struct drm_i915_private, mm.shrinker);
+ unsigned long num_objects;
+ unsigned long count;
+
+ count = READ_ONCE(i915->mm.shrink_memory) >> PAGE_SHIFT;
+ num_objects = READ_ONCE(i915->mm.shrink_count);
+
+ /*
+ * Update our preferred vmscan batch size for the next pass.
+ * Our rough guess for an effective batch size is roughly 2
+ * available GEM objects worth of pages. That is we don't want
+ * the shrinker to fire, until it is worth the cost of freeing an
+ * entire GEM object.
+ */
+ if (num_objects) {
+ unsigned long avg = 2 * count / num_objects;
+
+ i915->mm.shrinker.batch =
+ max((i915->mm.shrinker.batch + avg) >> 1,
+ 128ul /* default SHRINK_BATCH */);
+ }
+
+ return count;
+}
+
+static unsigned long
+i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
+{
+ struct drm_i915_private *i915 =
+ container_of(shrinker, struct drm_i915_private, mm.shrinker);
+ unsigned long freed;
+ bool unlock;
+
+ sc->nr_scanned = 0;
+
+ if (!shrinker_lock(i915, 0, &unlock))
+ return SHRINK_STOP;
+
+ freed = i915_gem_shrink(i915,
+ sc->nr_to_scan,
+ &sc->nr_scanned,
+ I915_SHRINK_BOUND |
+ I915_SHRINK_UNBOUND |
+ I915_SHRINK_WRITEBACK);
+ if (sc->nr_scanned < sc->nr_to_scan && current_is_kswapd()) {
+ intel_wakeref_t wakeref;
+
+ with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
+ freed += i915_gem_shrink(i915,
+ sc->nr_to_scan - sc->nr_scanned,
+ &sc->nr_scanned,
+ I915_SHRINK_ACTIVE |
+ I915_SHRINK_BOUND |
+ I915_SHRINK_UNBOUND |
+ I915_SHRINK_WRITEBACK);
+ }
+ }
+
+ shrinker_unlock(i915, unlock);
+
+ return sc->nr_scanned ? freed : SHRINK_STOP;
+}
+
+static int
+i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
+{
+ struct drm_i915_private *i915 =
+ container_of(nb, struct drm_i915_private, mm.oom_notifier);
+ struct drm_i915_gem_object *obj;
+ unsigned long unevictable, available, freed_pages;
+ intel_wakeref_t wakeref;
+ unsigned long flags;
+
+ freed_pages = 0;
+ with_intel_runtime_pm(&i915->runtime_pm, wakeref)
+ freed_pages += i915_gem_shrink(i915, -1UL, NULL,
+ I915_SHRINK_BOUND |
+ I915_SHRINK_UNBOUND |
+ I915_SHRINK_WRITEBACK);
+
+ /* Because we may be allocating inside our own driver, we cannot
+ * assert that there are no objects with pinned pages that are not
+ * being pointed to by hardware.
+ */
+ available = unevictable = 0;
+ spin_lock_irqsave(&i915->mm.obj_lock, flags);
+ list_for_each_entry(obj, &i915->mm.shrink_list, mm.link) {
+ if (!can_release_pages(obj))
+ unevictable += obj->base.size >> PAGE_SHIFT;
+ else
+ available += obj->base.size >> PAGE_SHIFT;
+ }
+ spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
+
+ if (freed_pages || available)
+ pr_info("Purging GPU memory, %lu pages freed, "
+ "%lu pages still pinned, %lu pages left available.\n",
+ freed_pages, unevictable, available);
+
+ *(unsigned long *)ptr += freed_pages;
+ return NOTIFY_DONE;
+}
+
+static int
+i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
+{
+ struct drm_i915_private *i915 =
+ container_of(nb, struct drm_i915_private, mm.vmap_notifier);
+ struct i915_vma *vma, *next;
+ unsigned long freed_pages = 0;
+ intel_wakeref_t wakeref;
+ bool unlock;
+
+ if (!shrinker_lock(i915, 0, &unlock))
+ return NOTIFY_DONE;
+
+ /* Force everything onto the inactive lists */
+ if (i915_gem_wait_for_idle(i915,
+ I915_WAIT_LOCKED,
+ MAX_SCHEDULE_TIMEOUT))
+ goto out;
+
+ with_intel_runtime_pm(&i915->runtime_pm, wakeref)
+ freed_pages += i915_gem_shrink(i915, -1UL, NULL,
+ I915_SHRINK_BOUND |
+ I915_SHRINK_UNBOUND |
+ I915_SHRINK_VMAPS);
+
+ /* We also want to clear any cached iomaps as they wrap vmap */
+ mutex_lock(&i915->ggtt.vm.mutex);
+ list_for_each_entry_safe(vma, next,
+ &i915->ggtt.vm.bound_list, vm_link) {
+ unsigned long count = vma->node.size >> PAGE_SHIFT;
+
+ if (!vma->iomap || i915_vma_is_active(vma))
+ continue;
+
+ mutex_unlock(&i915->ggtt.vm.mutex);
+ if (i915_vma_unbind(vma) == 0)
+ freed_pages += count;
+ mutex_lock(&i915->ggtt.vm.mutex);
+ }
+ mutex_unlock(&i915->ggtt.vm.mutex);
+
+out:
+ shrinker_unlock(i915, unlock);
+
+ *(unsigned long *)ptr += freed_pages;
+ return NOTIFY_DONE;
+}
+
+/**
+ * i915_gem_shrinker_register - Register the i915 shrinker
+ * @i915: i915 device
+ *
+ * This function registers and sets up the i915 shrinker and OOM handler.
+ */
+void i915_gem_shrinker_register(struct drm_i915_private *i915)
+{
+ i915->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
+ i915->mm.shrinker.count_objects = i915_gem_shrinker_count;
+ i915->mm.shrinker.seeks = DEFAULT_SEEKS;
+ i915->mm.shrinker.batch = 4096;
+ WARN_ON(register_shrinker(&i915->mm.shrinker));
+
+ i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
+ WARN_ON(register_oom_notifier(&i915->mm.oom_notifier));
+
+ i915->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
+ WARN_ON(register_vmap_purge_notifier(&i915->mm.vmap_notifier));
+}
+
+/**
+ * i915_gem_shrinker_unregister - Unregisters the i915 shrinker
+ * @i915: i915 device
+ *
+ * This function unregisters the i915 shrinker and OOM handler.
+ */
+void i915_gem_shrinker_unregister(struct drm_i915_private *i915)
+{
+ WARN_ON(unregister_vmap_purge_notifier(&i915->mm.vmap_notifier));
+ WARN_ON(unregister_oom_notifier(&i915->mm.oom_notifier));
+ unregister_shrinker(&i915->mm.shrinker);
+}
+
+void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
+ struct mutex *mutex)
+{
+ bool unlock = false;
+
+ if (!IS_ENABLED(CONFIG_LOCKDEP))
+ return;
+
+ if (!lockdep_is_held_type(&i915->drm.struct_mutex, -1)) {
+ mutex_acquire(&i915->drm.struct_mutex.dep_map,
+ I915_MM_NORMAL, 0, _RET_IP_);
+ unlock = true;
+ }
+
+ fs_reclaim_acquire(GFP_KERNEL);
+
+ /*
+ * As we invariably rely on the struct_mutex within the shrinker,
+ * but have a complicated recursion dance, taint all the mutexes used
+ * within the shrinker with the struct_mutex. For completeness, we
+ * taint with all subclass of struct_mutex, even though we should
+ * only need tainting by I915_MM_NORMAL to catch possible ABBA
+ * deadlocks from using struct_mutex inside @mutex.
+ */
+ mutex_acquire(&i915->drm.struct_mutex.dep_map,
+ I915_MM_SHRINKER, 0, _RET_IP_);
+
+ mutex_acquire(&mutex->dep_map, 0, 0, _RET_IP_);
+ mutex_release(&mutex->dep_map, 0, _RET_IP_);
+
+ mutex_release(&i915->drm.struct_mutex.dep_map, 0, _RET_IP_);
+
+ fs_reclaim_release(GFP_KERNEL);
+
+ if (unlock)
+ mutex_release(&i915->drm.struct_mutex.dep_map, 0, _RET_IP_);
+}