/*
* 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 "gt/intel_gt_requests.h"
#include "gt/intel_gt.h"
#include "i915_trace.h"
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;
/*
* 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 drop_pages(struct drm_i915_gem_object *obj,
unsigned long shrink, bool trylock_vm)
{
unsigned long flags;
flags = 0;
if (shrink & I915_SHRINK_ACTIVE)
flags |= I915_GEM_OBJECT_UNBIND_ACTIVE;
if (!(shrink & I915_SHRINK_BOUND))
flags |= I915_GEM_OBJECT_UNBIND_TEST;
if (trylock_vm)
flags |= I915_GEM_OBJECT_UNBIND_VM_TRYLOCK;
if (i915_gem_object_unbind(obj, flags) == 0)
return true;
return false;
}
static int try_to_writeback(struct drm_i915_gem_object *obj, unsigned int flags)
{
if (obj->ops->shrink) {
unsigned int shrink_flags = 0;
if (!(flags & I915_SHRINK_ACTIVE))
shrink_flags |= I915_GEM_OBJECT_SHRINK_NO_GPU_WAIT;
if (flags & I915_SHRINK_WRITEBACK)
shrink_flags |= I915_GEM_OBJECT_SHRINK_WRITEBACK;
return obj->ops->shrink(obj, shrink_flags);
}
return 0;
}
/**
* i915_gem_shrink - Shrink buffer object caches
* @ww: i915 gem ww acquire ctx, or NULL
* @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 i915_gem_ww_ctx *ww,
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;
int err = 0, i = 0;
struct intel_gt *gt;
/* CHV + VTD workaround use stop_machine(); need to trylock vm->mutex */
bool trylock_vm = !ww && intel_vm_no_concurrent_access_wa(i915);
trace_i915_gem_shrink(i915, target, shrink);
/*
* 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;
}
/*
* 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, but
* what we can do is give them a kick so that we do not keep idle
* contexts around longer than is necessary.
*/
if (shrink & I915_SHRINK_ACTIVE) {
for_each_gt(gt, i915, i)
/* Retire requests to unpin all idle contexts */
intel_gt_retire_requests(gt);
}
/*
* 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_framebuffer(obj))
continue;
if (!can_release_pages(obj))
continue;
if (!kref_get_unless_zero(&obj->base.refcount))
continue;
spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
/* May arrive from get_pages on another bo */
if (!ww) {
if (!i915_gem_object_trylock(obj, NULL))
goto skip;
} else {
err = i915_gem_object_lock(obj, ww);
if (err)
goto skip;
}
if (drop_pages(obj, shrink, trylock_vm) &&
!__i915_gem_object_put_pages(obj) &&
!try_to_writeback(obj, shrink))
count += obj->base.size >> PAGE_SHIFT;
if (!ww)
i915_gem_object_unlock(obj);
scanned += obj->base.size >> PAGE_SHIFT;
skip:
i915_gem_object_put(obj);
spin_lock_irqsave(&i915->mm.obj_lock, flags);
if (err)
break;
}
list_splice_tail(&still_in_list, phase->list);
spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
if (err)
break;
}
if (shrink & I915_SHRINK_BOUND)
intel_runtime_pm_put(&i915->runtime_pm, wakeref);
if (err)
return err;
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(NULL, i915, -1UL, NULL,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND);
}
return freed;
}
static unsigned long
i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
struct drm_i915_private *i915 = shrinker->private_data;
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 = shrinker->private_data;
unsigned long freed;
sc->nr_scanned = 0;
freed = i915_gem_shrink(NULL, i915,
sc->nr_to_scan,
&sc->nr_scanned,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND);
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(NULL, i915,
sc->nr_to_scan - sc->nr_scanned,
&sc->nr_scanned,
I915_SHRINK_ACTIVE |
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND |
I915_SHRINK_WRITEBACK);
}
}
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(NULL, 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;
struct intel_gt *gt;
int i;
with_intel_runtime_pm(&i915->runtime_pm, wakeref)
freed_pages += i915_gem_shrink(NULL, i915, -1UL, NULL,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND |
I915_SHRINK_VMAPS);
/* We also want to clear any cached iomaps as they wrap vmap */
for_each_gt(gt, i915, i) {
mutex_lock(>->ggtt->vm.mutex);
list_for_each_entry_safe(vma, next,
>->ggtt->vm.bound_list, vm_link) {
unsigned long count = i915_vma_size(vma) >> PAGE_SHIFT;
struct drm_i915_gem_object *obj = vma->obj;
if (!vma->iomap || i915_vma_is_active(vma))
continue;
if (!i915_gem_object_trylock(obj, NULL))
continue;
if (__i915_vma_unbind(vma) == 0)
freed_pages += count;
i915_gem_object_unlock(obj);
}
mutex_unlock(>->ggtt->vm.mutex);
}
*(unsigned long *)ptr += freed_pages;
return NOTIFY_DONE;
}
void i915_gem_driver_register__shrinker(struct drm_i915_private *i915)
{
i915->mm.shrinker = shrinker_alloc(0, "drm-i915_gem");
if (!i915->mm.shrinker) {
drm_WARN_ON(&i915->drm, 1);
} else {
i915->mm.shrinker->scan_objects = i915_gem_shrinker_scan;
i915->mm.shrinker->count_objects = i915_gem_shrinker_count;
i915->mm.shrinker->batch = 4096;
i915->mm.shrinker->private_data = i915;
shrinker_register(i915->mm.shrinker);
}
i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
drm_WARN_ON(&i915->drm, register_oom_notifier(&i915->mm.oom_notifier));
i915->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
drm_WARN_ON(&i915->drm,
register_vmap_purge_notifier(&i915->mm.vmap_notifier));
}
void i915_gem_driver_unregister__shrinker(struct drm_i915_private *i915)
{
drm_WARN_ON(&i915->drm,
unregister_vmap_purge_notifier(&i915->mm.vmap_notifier));
drm_WARN_ON(&i915->drm,
unregister_oom_notifier(&i915->mm.oom_notifier));
shrinker_free(i915->mm.shrinker);
}
void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
struct mutex *mutex)
{
if (!IS_ENABLED(CONFIG_LOCKDEP))
return;
fs_reclaim_acquire(GFP_KERNEL);
mutex_acquire(&mutex->dep_map, 0, 0, _RET_IP_);
mutex_release(&mutex->dep_map, _RET_IP_);
fs_reclaim_release(GFP_KERNEL);
}
/**
* i915_gem_object_make_unshrinkable - Hide the object from the shrinker. By
* default all object types that support shrinking(see IS_SHRINKABLE), will also
* make the object visible to the shrinker after allocating the system memory
* pages.
* @obj: The GEM object.
*
* This is typically used for special kernel internal objects that can't be
* easily processed by the shrinker, like if they are perma-pinned.
*/
void i915_gem_object_make_unshrinkable(struct drm_i915_gem_object *obj)
{
struct drm_i915_private *i915 = obj_to_i915(obj);
unsigned long flags;
/*
* We can only be called while the pages are pinned or when
* the pages are released. If pinned, we should only be called
* from a single caller under controlled conditions; and on release
* only one caller may release us. Neither the two may cross.
*/
if (atomic_add_unless(&obj->mm.shrink_pin, 1, 0))
return;
spin_lock_irqsave(&i915->mm.obj_lock, flags);
if (!atomic_fetch_inc(&obj->mm.shrink_pin) &&
!list_empty(&obj->mm.link)) {
list_del_init(&obj->mm.link);
i915->mm.shrink_count--;
i915->mm.shrink_memory -= obj->base.size;
}
spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
}
static void ___i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj,
struct list_head *head)
{
struct drm_i915_private *i915 = obj_to_i915(obj);
unsigned long flags;
if (!i915_gem_object_is_shrinkable(obj))
return;
if (atomic_add_unless(&obj->mm.shrink_pin, -1, 1))
return;
spin_lock_irqsave(&i915->mm.obj_lock, flags);
GEM_BUG_ON(!kref_read(&obj->base.refcount));
if (atomic_dec_and_test(&obj->mm.shrink_pin)) {
GEM_BUG_ON(!list_empty(&obj->mm.link));
list_add_tail(&obj->mm.link, head);
i915->mm.shrink_count++;
i915->mm.shrink_memory += obj->base.size;
}
spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
}
/**
* __i915_gem_object_make_shrinkable - Move the object to the tail of the
* shrinkable list. Objects on this list might be swapped out. Used with
* WILLNEED objects.
* @obj: The GEM object.
*
* DO NOT USE. This is intended to be called on very special objects that don't
* yet have mm.pages, but are guaranteed to have potentially reclaimable pages
* underneath.
*/
void __i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj)
{
___i915_gem_object_make_shrinkable(obj,
&obj_to_i915(obj)->mm.shrink_list);
}
/**
* __i915_gem_object_make_purgeable - Move the object to the tail of the
* purgeable list. Objects on this list might be swapped out. Used with
* DONTNEED objects.
* @obj: The GEM object.
*
* DO NOT USE. This is intended to be called on very special objects that don't
* yet have mm.pages, but are guaranteed to have potentially reclaimable pages
* underneath.
*/
void __i915_gem_object_make_purgeable(struct drm_i915_gem_object *obj)
{
___i915_gem_object_make_shrinkable(obj,
&obj_to_i915(obj)->mm.purge_list);
}
/**
* i915_gem_object_make_shrinkable - Move the object to the tail of the
* shrinkable list. Objects on this list might be swapped out. Used with
* WILLNEED objects.
* @obj: The GEM object.
*
* MUST only be called on objects which have backing pages.
*
* MUST be balanced with previous call to i915_gem_object_make_unshrinkable().
*/
void i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj)
{
GEM_BUG_ON(!i915_gem_object_has_pages(obj));
__i915_gem_object_make_shrinkable(obj);
}
/**
* i915_gem_object_make_purgeable - Move the object to the tail of the purgeable
* list. Used with DONTNEED objects. Unlike with shrinkable objects, the
* shrinker will attempt to discard the backing pages, instead of trying to swap
* them out.
* @obj: The GEM object.
*
* MUST only be called on objects which have backing pages.
*
* MUST be balanced with previous call to i915_gem_object_make_unshrinkable().
*/
void i915_gem_object_make_purgeable(struct drm_i915_gem_object *obj)
{
GEM_BUG_ON(!i915_gem_object_has_pages(obj));
__i915_gem_object_make_purgeable(obj);
}
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