Commit 1233e2db authored by Chris Wilson's avatar Chris Wilson

drm/i915: Move object backing storage manipulation to its own locking

Break the allocation of the backing storage away from struct_mutex into
a per-object lock. This allows parallel page allocation, provided we can
do so outside of struct_mutex (i.e. set-domain-ioctl, pwrite, GTT
fault), i.e. before execbuf! The increased cost of the atomic counters
are hidden behind i915_vma_pin() for the typical case of execbuf, i.e.
as the object is typically bound between execbufs, the page_pin_count is
static. The cost will be felt around set-domain and pwrite, but offset
by the improvement from reduced struct_mutex contention.
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-14-chris@chris-wilson.co.uk
parent 03ac84f1
......@@ -2274,7 +2274,8 @@ struct drm_i915_gem_object {
unsigned int pin_display;
struct {
unsigned int pages_pin_count;
struct mutex lock; /* protects the pages and their use */
atomic_t pages_pin_count;
struct sg_table *pages;
void *mapping;
......@@ -2387,13 +2388,6 @@ i915_gem_object_is_dead(const struct drm_i915_gem_object *obj)
return atomic_read(&obj->base.refcount.refcount) == 0;
}
#if IS_ENABLED(CONFIG_LOCKDEP)
#define lockdep_assert_held_unless(lock, cond) \
GEM_BUG_ON(debug_locks && !lockdep_is_held(lock) && !(cond))
#else
#define lockdep_assert_held_unless(lock, cond)
#endif
static inline bool
i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj)
{
......@@ -3229,9 +3223,9 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
static inline int __must_check
i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
{
lockdep_assert_held(&obj->base.dev->struct_mutex);
might_lock(&obj->mm.lock);
if (obj->mm.pages_pin_count++)
if (atomic_inc_not_zero(&obj->mm.pages_pin_count))
return 0;
return __i915_gem_object_get_pages(obj);
......@@ -3240,32 +3234,29 @@ i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
static inline void
__i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
{
lockdep_assert_held_unless(&obj->base.dev->struct_mutex,
i915_gem_object_is_dead(obj));
GEM_BUG_ON(!obj->mm.pages);
obj->mm.pages_pin_count++;
atomic_inc(&obj->mm.pages_pin_count);
}
static inline bool
i915_gem_object_has_pinned_pages(struct drm_i915_gem_object *obj)
{
return obj->mm.pages_pin_count;
return atomic_read(&obj->mm.pages_pin_count);
}
static inline void
__i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
{
lockdep_assert_held_unless(&obj->base.dev->struct_mutex,
i915_gem_object_is_dead(obj));
GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
GEM_BUG_ON(!obj->mm.pages);
obj->mm.pages_pin_count--;
GEM_BUG_ON(obj->mm.pages_pin_count < obj->bind_count);
atomic_dec(&obj->mm.pages_pin_count);
GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
}
static inline void i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
static inline void
i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
{
__i915_gem_object_unpin_pages(obj);
}
......@@ -3288,8 +3279,8 @@ enum i915_map_type {
* the kernel address space. Based on the @type of mapping, the PTE will be
* set to either WriteBack or WriteCombine (via pgprot_t).
*
* The caller must hold the struct_mutex, and is responsible for calling
* i915_gem_object_unpin_map() when the mapping is no longer required.
* The caller is responsible for calling i915_gem_object_unpin_map() when the
* mapping is no longer required.
*
* Returns the pointer through which to access the mapped object, or an
* ERR_PTR() on error.
......@@ -3305,12 +3296,9 @@ void *__must_check i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
* with your access, call i915_gem_object_unpin_map() to release the pin
* upon the mapping. Once the pin count reaches zero, that mapping may be
* removed.
*
* The caller must hold the struct_mutex.
*/
static inline void i915_gem_object_unpin_map(struct drm_i915_gem_object *obj)
{
lockdep_assert_held(&obj->base.dev->struct_mutex);
i915_gem_object_unpin_pages(obj);
}
......
......@@ -2269,6 +2269,9 @@ void __i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
{
struct address_space *mapping;
lockdep_assert_held(&obj->mm.lock);
GEM_BUG_ON(obj->mm.pages);
switch (obj->mm.madv) {
case I915_MADV_DONTNEED:
i915_gem_object_truncate(obj);
......@@ -2325,12 +2328,17 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
{
struct sg_table *pages;
lockdep_assert_held(&obj->base.dev->struct_mutex);
if (i915_gem_object_has_pinned_pages(obj))
return;
GEM_BUG_ON(obj->bind_count);
if (!READ_ONCE(obj->mm.pages))
return;
/* May be called by shrinker from within get_pages() (on another bo) */
mutex_lock_nested(&obj->mm.lock, SINGLE_DEPTH_NESTING);
if (unlikely(atomic_read(&obj->mm.pages_pin_count)))
goto unlock;
/* ->put_pages might need to allocate memory for the bit17 swizzle
* array, hence protect them from being reaped by removing them from gtt
......@@ -2353,6 +2361,8 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
__i915_gem_object_reset_page_iter(obj);
obj->ops->put_pages(obj, pages);
unlock:
mutex_unlock(&obj->mm.lock);
}
static unsigned int swiotlb_max_size(void)
......@@ -2486,7 +2496,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
struct sg_table *pages)
{
lockdep_assert_held(&obj->base.dev->struct_mutex);
lockdep_assert_held(&obj->mm.lock);
obj->mm.get_page.sg_pos = pages->sgl;
obj->mm.get_page.sg_idx = 0;
......@@ -2512,9 +2522,9 @@ static int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
}
/* Ensure that the associated pages are gathered from the backing storage
* and pinned into our object. i915_gem_object_get_pages() may be called
* and pinned into our object. i915_gem_object_pin_pages() may be called
* multiple times before they are released by a single call to
* i915_gem_object_put_pages() - once the pages are no longer referenced
* i915_gem_object_unpin_pages() - once the pages are no longer referenced
* either as a result of memory pressure (reaping pages under the shrinker)
* or as the object is itself released.
*/
......@@ -2522,15 +2532,23 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
int err;
lockdep_assert_held(&obj->base.dev->struct_mutex);
err = mutex_lock_interruptible(&obj->mm.lock);
if (err)
return err;
if (obj->mm.pages)
return 0;
if (likely(obj->mm.pages)) {
__i915_gem_object_pin_pages(obj);
goto unlock;
}
GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
err = ____i915_gem_object_get_pages(obj);
if (err)
__i915_gem_object_unpin_pages(obj);
if (!err)
atomic_set_release(&obj->mm.pages_pin_count, 1);
unlock:
mutex_unlock(&obj->mm.lock);
return err;
}
......@@ -2590,20 +2608,29 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
void *ptr;
int ret;
lockdep_assert_held(&obj->base.dev->struct_mutex);
GEM_BUG_ON(!i915_gem_object_has_struct_page(obj));
ret = i915_gem_object_pin_pages(obj);
ret = mutex_lock_interruptible(&obj->mm.lock);
if (ret)
return ERR_PTR(ret);
pinned = obj->mm.pages_pin_count > 1;
pinned = true;
if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) {
ret = ____i915_gem_object_get_pages(obj);
if (ret)
goto err_unlock;
GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count));
atomic_set_release(&obj->mm.pages_pin_count, 1);
pinned = false;
}
GEM_BUG_ON(!obj->mm.pages);
ptr = ptr_unpack_bits(obj->mm.mapping, has_type);
if (ptr && has_type != type) {
if (pinned) {
ret = -EBUSY;
goto err;
goto err_unpin;
}
if (is_vmalloc_addr(ptr))
......@@ -2618,17 +2645,21 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
ptr = i915_gem_object_map(obj, type);
if (!ptr) {
ret = -ENOMEM;
goto err;
goto err_unpin;
}
obj->mm.mapping = ptr_pack_bits(ptr, type);
}
out_unlock:
mutex_unlock(&obj->mm.lock);
return ptr;
err:
i915_gem_object_unpin_pages(obj);
return ERR_PTR(ret);
err_unpin:
atomic_dec(&obj->mm.pages_pin_count);
err_unlock:
ptr = ERR_PTR(ret);
goto out_unlock;
}
static void
......@@ -4268,7 +4299,7 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
struct drm_i915_private *dev_priv = to_i915(dev);
struct drm_i915_gem_madvise *args = data;
struct drm_i915_gem_object *obj;
int ret;
int err;
switch (args->madv) {
case I915_MADV_DONTNEED:
......@@ -4278,15 +4309,13 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
return -EINVAL;
}
ret = i915_mutex_lock_interruptible(dev);
if (ret)
return ret;
obj = i915_gem_object_lookup(file_priv, args->handle);
if (!obj) {
ret = -ENOENT;
goto unlock;
}
if (!obj)
return -ENOENT;
err = mutex_lock_interruptible(&obj->mm.lock);
if (err)
goto out;
if (obj->mm.pages &&
i915_gem_object_is_tiled(obj) &&
......@@ -4305,11 +4334,11 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
i915_gem_object_truncate(obj);
args->retained = obj->mm.madv != __I915_MADV_PURGED;
mutex_unlock(&obj->mm.lock);
out:
i915_gem_object_put(obj);
unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
return err;
}
void i915_gem_object_init(struct drm_i915_gem_object *obj,
......@@ -4317,6 +4346,8 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
{
int i;
mutex_init(&obj->mm.lock);
INIT_LIST_HEAD(&obj->global_list);
INIT_LIST_HEAD(&obj->userfault_link);
for (i = 0; i < I915_NUM_ENGINES; i++)
......@@ -4479,7 +4510,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
obj->ops->release(obj);
if (WARN_ON(i915_gem_object_has_pinned_pages(obj)))
obj->mm.pages_pin_count = 0;
atomic_set(&obj->mm.pages_pin_count, 0);
if (discard_backing_storage(obj))
obj->mm.madv = I915_MADV_DONTNEED;
__i915_gem_object_put_pages(obj);
......
......@@ -48,6 +48,20 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
#endif
}
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;
*unlock = false;
} else {
*unlock = true;
}
return true;
}
static bool any_vma_pinned(struct drm_i915_gem_object *obj)
{
struct i915_vma *vma;
......@@ -66,6 +80,9 @@ static bool swap_available(void)
static bool can_release_pages(struct drm_i915_gem_object *obj)
{
if (!obj->mm.pages)
return false;
/* Only shmemfs objects are backed by swap */
if (!obj->base.filp)
return false;
......@@ -78,7 +95,7 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
* to the GPU, simply unbinding from the GPU is not going to succeed
* in releasing our pin count on the pages themselves.
*/
if (obj->mm.pages_pin_count > obj->bind_count)
if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count)
return false;
if (any_vma_pinned(obj))
......@@ -95,7 +112,7 @@ static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
{
if (i915_gem_object_unbind(obj) == 0)
__i915_gem_object_put_pages(obj);
return !obj->mm.pages;
return !READ_ONCE(obj->mm.pages);
}
/**
......@@ -135,6 +152,10 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
{ NULL, 0 },
}, *phase;
unsigned long count = 0;
bool unlock;
if (!i915_gem_shrinker_lock(&dev_priv->drm, &unlock))
return 0;
trace_i915_gem_shrink(dev_priv, target, flags);
i915_gem_retire_requests(dev_priv);
......@@ -199,8 +220,14 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
i915_gem_object_get(obj);
if (unsafe_drop_pages(obj))
count += obj->base.size >> PAGE_SHIFT;
if (unsafe_drop_pages(obj)) {
mutex_lock(&obj->mm.lock);
if (!obj->mm.pages) {
__i915_gem_object_invalidate(obj);
count += obj->base.size >> PAGE_SHIFT;
}
mutex_unlock(&obj->mm.lock);
}
i915_gem_object_put(obj);
}
......@@ -211,6 +238,9 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
intel_runtime_pm_put(dev_priv);
i915_gem_retire_requests(dev_priv);
if (unlock)
mutex_unlock(&dev_priv->drm.struct_mutex);
/* expedite the RCU grace period to free some request slabs */
synchronize_rcu_expedited();
......@@ -244,19 +274,6 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
return freed;
}
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;
*unlock = false;
} else
*unlock = true;
return true;
}
static unsigned long
i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
......
......@@ -259,6 +259,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
if (!err) {
struct i915_vma *vma;
mutex_lock(&obj->mm.lock);
if (obj->mm.pages &&
obj->mm.madv == I915_MADV_WILLNEED &&
dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
......@@ -267,6 +268,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
if (!i915_gem_object_is_tiled(obj))
__i915_gem_object_pin_pages(obj);
}
mutex_unlock(&obj->mm.lock);
list_for_each_entry(vma, &obj->vma_list, obj_link) {
if (!vma->fence)
......
......@@ -79,7 +79,7 @@ static void cancel_userptr(struct work_struct *work)
WARN_ONCE(obj->mm.pages,
"Failed to release pages: bind_count=%d, pages_pin_count=%d, pin_display=%d\n",
obj->bind_count,
obj->mm.pages_pin_count,
atomic_read(&obj->mm.pages_pin_count),
obj->pin_display);
i915_gem_object_put(obj);
......@@ -491,7 +491,6 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
{
struct get_pages_work *work = container_of(_work, typeof(*work), work);
struct drm_i915_gem_object *obj = work->obj;
struct drm_device *dev = obj->base.dev;
const int npages = obj->base.size >> PAGE_SHIFT;
struct page **pvec;
int pinned, ret;
......@@ -527,7 +526,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
}
}
mutex_lock(&dev->struct_mutex);
mutex_lock(&obj->mm.lock);
if (obj->userptr.work == &work->work) {
struct sg_table *pages = ERR_PTR(ret);
......@@ -542,13 +541,12 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
obj->userptr.work = ERR_CAST(pages);
}
i915_gem_object_put(obj);
mutex_unlock(&dev->struct_mutex);
mutex_unlock(&obj->mm.lock);
release_pages(pvec, pinned, 0);
drm_free_large(pvec);
i915_gem_object_put_unlocked(obj);
put_task_struct(work->task);
kfree(work);
}
......
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