/*
* 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/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_drv.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) > 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 __start_writeback(struct drm_i915_gem_object *obj,
unsigned int flags)
{
struct address_space *mapping;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
.for_reclaim = 1,
};
unsigned long i;
lockdep_assert_held(&obj->mm.lock);
GEM_BUG_ON(i915_gem_object_has_pages(obj));
switch (obj->mm.madv) {
case I915_MADV_DONTNEED:
__i915_gem_object_truncate(obj);
case __I915_MADV_PURGED:
return;
}
if (!obj->base.filp)
return;
if (!(flags & I915_SHRINK_WRITEBACK))
return;
/*
* Leave mmapings intact (GTT will have been revoked on unbinding,
* leaving only CPU mmapings around) and add those pages to the LRU
* instead of invoking writeback so they are aged and paged out
* as normal.
*/
mapping = obj->base.filp->f_mapping;
/* Begin writeback on each dirty page */
for (i = 0; i < obj->base.size >> PAGE_SHIFT; i++) {
struct page *page;
page = find_lock_entry(mapping, i);
if (!page || xa_is_value(page))
continue;
if (!page_mapped(page) && clear_page_dirty_for_io(page)) {
int ret;
SetPageReclaim(page);
ret = mapping->a_ops->writepage(page, &wbc);
if (!PageWriteback(page))
ClearPageReclaim(page);
if (!ret)
goto put;
}
unlock_page(page);
put:
put_page(page);
}
}
/**
* 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)
* @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 *i915,
unsigned long target,
unsigned long *nr_scanned,
unsigned flags)
{
const struct {
struct list_head *list;
unsigned int bit;
} phases[] = {
{ &i915->mm.unbound_list, I915_SHRINK_UNBOUND },
{ &i915->mm.bound_list, I915_SHRINK_BOUND },
{ NULL, 0 },
}, *phase;
intel_wakeref_t wakeref = 0;
unsigned long count = 0;
unsigned long scanned = 0;
bool unlock;
if (!shrinker_lock(i915, flags, &unlock))
return 0;
/*
* When shrinking the active list, 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.
*
* We don't care about errors here; if we cannot wait upon the GPU,
* we will free as much as we can and hope to get a second chance.
*/
if (flags & I915_SHRINK_ACTIVE)
i915_gem_wait_for_idle(i915,
I915_WAIT_LOCKED,
MAX_SCHEDULE_TIMEOUT);
trace_i915_gem_shrink(i915, target, flags);
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 (flags & I915_SHRINK_BOUND) {
wakeref = intel_runtime_pm_get_if_in_use(i915);
if (!wakeref)
flags &= ~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;
if ((flags & 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(&i915->mm.obj_lock);
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 (flags & I915_SHRINK_PURGEABLE &&
obj->mm.madv != I915_MADV_DONTNEED)
continue;
if (flags & I915_SHRINK_VMAPS &&
!is_vmalloc_addr(obj->mm.mapping))
continue;
if (!(flags & I915_SHRINK_ACTIVE) &&
(i915_gem_object_is_active(obj) ||
i915_gem_object_is_framebuffer(obj)))
continue;
if (!can_release_pages(obj))
continue;
spin_unlock(&i915->mm.obj_lock);
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)) {
__start_writeback(obj, flags);
count += obj->base.size >> PAGE_SHIFT;
}
mutex_unlock(&obj->mm.lock);
}
scanned += obj->base.size >> PAGE_SHIFT;
spin_lock(&i915->mm.obj_lock);
}
list_splice_tail(&still_in_list, phase->list);
spin_unlock(&i915->mm.obj_lock);
}
if (flags & I915_SHRINK_BOUND)
intel_runtime_pm_put(i915, 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, 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);
struct drm_i915_gem_object *obj;
unsigned long num_objects = 0;
unsigned long count = 0;
spin_lock(&i915->mm.obj_lock);
list_for_each_entry(obj, &i915->mm.unbound_list, mm.link)
if (can_release_pages(obj)) {
count += obj->base.size >> PAGE_SHIFT;
num_objects++;
}
list_for_each_entry(obj, &i915->mm.bound_list, mm.link)
if (!i915_gem_object_is_active(obj) && can_release_pages(obj)) {
count += obj->base.size >> PAGE_SHIFT;
num_objects++;
}
spin_unlock(&i915->mm.obj_lock);
/* 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_PURGEABLE |
I915_SHRINK_WRITEBACK);
if (sc->nr_scanned < sc->nr_to_scan)
freed += i915_gem_shrink(i915,
sc->nr_to_scan - sc->nr_scanned,
&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, 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, bound, unbound, freed_pages;
intel_wakeref_t wakeref;
freed_pages = 0;
with_intel_runtime_pm(i915, 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.
*/
unbound = bound = unevictable = 0;
spin_lock(&i915->mm.obj_lock);
list_for_each_entry(obj, &i915->mm.unbound_list, mm.link) {
if (!can_release_pages(obj))
unevictable += obj->base.size >> PAGE_SHIFT;
else
unbound += obj->base.size >> PAGE_SHIFT;
}
list_for_each_entry(obj, &i915->mm.bound_list, mm.link) {
if (!can_release_pages(obj))
unevictable += obj->base.size >> PAGE_SHIFT;
else
bound += obj->base.size >> PAGE_SHIFT;
}
spin_unlock(&i915->mm.obj_lock);
if (freed_pages || unbound || bound)
pr_info("Purging GPU memory, %lu pages freed, "
"%lu pages still pinned.\n",
freed_pages, unevictable);
*(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, 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_);
}
