[dragonfly.git] / sys / dev / drm / i915 / i915_gem_shrinker.c

/*
 * Copyright © 2008-2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

#include <linux/shmem_fs.h>
#include <linux/swap.h>
#include <linux/pci.h>
#include <linux/vmalloc.h>
#include <drm/drmP.h>
#include <drm/i915_drm.h>

#include "i915_drv.h"
#include "i915_trace.h"

#if 0
static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
{
        if (!mutex_is_locked(mutex))
                return false;

#if defined(CONFIG_DEBUG_MUTEXES) || defined(CONFIG_MUTEX_SPIN_ON_OWNER)
        return mutex->owner == task;
#else
        /* Since UP may be pre-empted, we cannot assume that we own the lock */
        return false;
#endif
}
#endif

static int num_vma_bound(struct drm_i915_gem_object *obj)
{
        struct i915_vma *vma;
        int count = 0;

        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                if (drm_mm_node_allocated(&vma->node))
                        count++;
                if (vma->pin_count)
                        count++;
        }

        return count;
}

static bool swap_available(void)
{
        return get_nr_swap_pages() > 0;
}

static bool can_release_pages(struct drm_i915_gem_object *obj)
{
        /* Only shmemfs objects are backed by swap */
        if (!obj->base.filp)
                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 (obj->pages_pin_count != num_vma_bound(obj))
                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->madv == I915_MADV_DONTNEED;
}

/**
 * i915_gem_shrink - Shrink buffer object caches
 * @dev_priv: i915 device
 * @target: amount of memory to make available, in pages
 * @flags: 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 *dev_priv,
                unsigned long target, unsigned flags)
{
        const struct {
                struct list_head *list;
                unsigned int bit;
        } phases[] = {
                { &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
                { &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
                { NULL, 0 },
        }, *phase;
        unsigned long count = 0;

        trace_i915_gem_shrink(dev_priv, target, flags);
        i915_gem_retire_requests(dev_priv->dev);

        /*
         * 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;

                if ((flags & phase->bit) == 0)
                        continue;

                INIT_LIST_HEAD(&still_in_list);
                while (count < target && !list_empty(phase->list)) {
                        struct drm_i915_gem_object *obj;
                        struct i915_vma *vma, *v;

                        obj = list_first_entry(phase->list,
                                               typeof(*obj), global_list);
                        list_move_tail(&obj->global_list, &still_in_list);

                        if (flags & I915_SHRINK_PURGEABLE &&
                            obj->madv != I915_MADV_DONTNEED)
                                continue;

                        if (flags & I915_SHRINK_VMAPS &&
                            !is_vmalloc_addr(obj->mapping))
                                continue;

                        if ((flags & I915_SHRINK_ACTIVE) == 0 && obj->active)
                                continue;

                        if (!can_release_pages(obj))
                                continue;

                        drm_gem_object_reference(&obj->base);

                        /* For the unbound phase, this should be a no-op! */
                        list_for_each_entry_safe(vma, v,
                                                 &obj->vma_list, obj_link)
                                if (i915_vma_unbind(vma))
                                        break;

                        if (i915_gem_object_put_pages(obj) == 0)
                                count += obj->base.size >> PAGE_SHIFT;

                        drm_gem_object_unreference(&obj->base);
                }
                list_splice(&still_in_list, phase->list);
        }

        i915_gem_retire_requests(dev_priv->dev);

        return count;
}

/**
 * i915_gem_shrink_all - Shrink buffer object caches completely
 * @dev_priv: 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 *dev_priv)
{
        return i915_gem_shrink(dev_priv, -1UL,
                               I915_SHRINK_BOUND |
                               I915_SHRINK_UNBOUND |
                               I915_SHRINK_ACTIVE);
}

#if 0
static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
{
        if (!mutex_trylock(&dev->struct_mutex)) {
                if (!mutex_is_locked_by(&dev->struct_mutex, current))
                        return false;

                if (to_i915(dev)->mm.shrinker_no_lock_stealing)
                        return false;

                *unlock = false;
        } else
                *unlock = true;

        return true;
}

static unsigned long
i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
        struct drm_i915_private *dev_priv =
                container_of(shrinker, struct drm_i915_private, mm.shrinker);
        struct drm_device *dev = dev_priv->dev;
        struct drm_i915_gem_object *obj;
        unsigned long count;
        bool unlock;

        if (!i915_gem_shrinker_lock(dev, &unlock))
                return 0;

        count = 0;
        list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list)
                if (can_release_pages(obj))
                        count += obj->base.size >> PAGE_SHIFT;

        list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
                if (!obj->active && can_release_pages(obj))
                        count += obj->base.size >> PAGE_SHIFT;
        }

        if (unlock)
                mutex_unlock(&dev->struct_mutex);

        return count;
}

static unsigned long
i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
{
        struct drm_i915_private *dev_priv =
                container_of(shrinker, struct drm_i915_private, mm.shrinker);
        struct drm_device *dev = dev_priv->dev;
        unsigned long freed;
        bool unlock;

        if (!i915_gem_shrinker_lock(dev, &unlock))
                return SHRINK_STOP;

        freed = i915_gem_shrink(dev_priv,
                                sc->nr_to_scan,
                                I915_SHRINK_BOUND |
                                I915_SHRINK_UNBOUND |
                                I915_SHRINK_PURGEABLE);
        if (freed < sc->nr_to_scan)
                freed += i915_gem_shrink(dev_priv,
                                         sc->nr_to_scan - freed,
                                         I915_SHRINK_BOUND |
                                         I915_SHRINK_UNBOUND);
        if (unlock)
                mutex_unlock(&dev->struct_mutex);

        return freed;
}

struct shrinker_lock_uninterruptible {
        bool was_interruptible;
        bool unlock;
};

static bool
i915_gem_shrinker_lock_uninterruptible(struct drm_i915_private *dev_priv,
                                       struct shrinker_lock_uninterruptible *slu,
                                       int timeout_ms)
{
        unsigned long timeout = msecs_to_jiffies(timeout_ms) + 1;

        while (!i915_gem_shrinker_lock(dev_priv->dev, &slu->unlock)) {
                schedule_timeout_killable(1);
                if (fatal_signal_pending(current))
                        return false;
                if (--timeout == 0) {
                        pr_err("Unable to lock GPU to purge memory.\n");
                        return false;
                }
        }

        slu->was_interruptible = dev_priv->mm.interruptible;
        dev_priv->mm.interruptible = false;
        return true;
}

static void
i915_gem_shrinker_unlock_uninterruptible(struct drm_i915_private *dev_priv,
                                         struct shrinker_lock_uninterruptible *slu)
{
        dev_priv->mm.interruptible = slu->was_interruptible;
        if (slu->unlock)
                mutex_unlock(&dev_priv->dev->struct_mutex);
}

static int
i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
{
        struct drm_i915_private *dev_priv =
                container_of(nb, struct drm_i915_private, mm.oom_notifier);
        struct shrinker_lock_uninterruptible slu;
        struct drm_i915_gem_object *obj;
        unsigned long unevictable, bound, unbound, freed_pages;

        if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
                return NOTIFY_DONE;

        freed_pages = i915_gem_shrink_all(dev_priv);

        /* 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.
         */
        unbound = bound = unevictable = 0;
        list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_list) {
                if (!can_release_pages(obj))
                        unevictable += obj->base.size >> PAGE_SHIFT;
                else
                        unbound += obj->base.size >> PAGE_SHIFT;
        }
        list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
                if (!can_release_pages(obj))
                        unevictable += obj->base.size >> PAGE_SHIFT;
                else
                        bound += obj->base.size >> PAGE_SHIFT;
        }

        i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);

        if (freed_pages || unbound || bound)
                pr_info("Purging GPU memory, %lu pages freed, "
                        "%lu pages still pinned.\n",
                        freed_pages, unevictable);
        if (unbound || bound)
                pr_err("%lu and %lu pages still available in the "
                       "bound and unbound GPU page lists.\n",
                       bound, unbound);

        *(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 *dev_priv =
                container_of(nb, struct drm_i915_private, mm.vmap_notifier);
        struct shrinker_lock_uninterruptible slu;
        unsigned long freed_pages;

        if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
                return NOTIFY_DONE;

        freed_pages = i915_gem_shrink(dev_priv, -1UL,
                                      I915_SHRINK_BOUND |
                                      I915_SHRINK_UNBOUND |
                                      I915_SHRINK_ACTIVE |
                                      I915_SHRINK_VMAPS);

        i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);

        *(unsigned long *)ptr += freed_pages;
        return NOTIFY_DONE;
}
#endif

/**
 * i915_gem_shrinker_init - Initialize i915 shrinker
 * @dev_priv: i915 device
 *
 * This function registers and sets up the i915 shrinker and OOM handler.
 */
void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
{
#if 0
        dev_priv->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
        dev_priv->mm.shrinker.count_objects = i915_gem_shrinker_count;
        dev_priv->mm.shrinker.seeks = DEFAULT_SEEKS;
        WARN_ON(register_shrinker(&dev_priv->mm.shrinker));

        dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
        WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));

        dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
        WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
#endif
}

/**
 * i915_gem_shrinker_cleanup - Clean up i915 shrinker
 * @dev_priv: i915 device
 *
 * This function unregisters the i915 shrinker and OOM handler.
 */
void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
{
#if 0
        WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
        WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
        unregister_shrinker(&dev_priv->mm.shrinker);
#endif
}