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drm/i915/gem: Store mmap_offsets in an rbtree rather than a plain list

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Currently we create a new mmap_offset for every call to
mmap_offset_ioctl. This exposes ourselves to an abusive client that may
simply create new mmap_offsets ad infinitum, which will exhaust physical
memory and the virtual address space. In addition to the exhaustion, a
very long linear list of mmap_offsets causes other clients using the
object to incur long list walks -- these long lists can also be
generated by simply having many clients generate their own mmap_offset.

However, we can simply use the drm_vma_node itself to manage the file
association (allow/revoke) dropping our need to keep an mmo per-file.
Then if we keep a small rbtree of per-type mmap_offsets, we can lookup
duplicate requests quickly.

Fixes: cc662126b4 ("drm/i915: Introduce DRM_I915_GEM_MMAP_OFFSET")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Reviewed-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200120104924.4000706-3-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2020-01-20 10:49:22 +00:00
parent 814df0ce5e
commit 7865559872
3 changed files with 85 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

90
drivers/gpu/drm/i915/gem/i915_gem_mman.c
View File

@ -455,10 +455,11 @@ out:
void i915_gem_object_release_mmap_offset(struct drm_i915_gem_object *obj)
{
struct i915_mmap_offset *mmo;
struct i915_mmap_offset *mmo, *mn;
spin_lock(&obj->mmo.lock);
list_for_each_entry(mmo, &obj->mmo.offsets, offset) {
rbtree_postorder_for_each_entry_safe(mmo, mn,
&obj->mmo.offsets, offset) {
/*
* vma_node_unmap for GTT mmaps handled already in
* __i915_gem_object_release_mmap_gtt
@ -487,6 +488,67 @@ void i915_gem_object_release_mmap(struct drm_i915_gem_object *obj)
i915_gem_object_release_mmap_offset(obj);
}
static struct i915_mmap_offset *
lookup_mmo(struct drm_i915_gem_object *obj,
enum i915_mmap_type mmap_type)
{
struct rb_node *rb;
spin_lock(&obj->mmo.lock);
rb = obj->mmo.offsets.rb_node;
while (rb) {
struct i915_mmap_offset *mmo =
rb_entry(rb, typeof(*mmo), offset);
if (mmo->mmap_type == mmap_type) {
spin_unlock(&obj->mmo.lock);
return mmo;
}
if (mmo->mmap_type < mmap_type)
rb = rb->rb_right;
else
rb = rb->rb_left;
}
spin_unlock(&obj->mmo.lock);
return NULL;
}
static struct i915_mmap_offset *
insert_mmo(struct drm_i915_gem_object *obj, struct i915_mmap_offset *mmo)
{
struct rb_node *rb, **p;
spin_lock(&obj->mmo.lock);
rb = NULL;
p = &obj->mmo.offsets.rb_node;
while (*p) {
struct i915_mmap_offset *pos;
rb = *p;
pos = rb_entry(rb, typeof(*pos), offset);
if (pos->mmap_type == mmo->mmap_type) {
spin_unlock(&obj->mmo.lock);
drm_vma_offset_remove(obj->base.dev->vma_offset_manager,
&mmo->vma_node);
kfree(mmo);
return pos;
}
if (pos->mmap_type < mmo->mmap_type)
p = &rb->rb_right;
else
p = &rb->rb_left;
}
rb_link_node(&mmo->offset, rb, p);
rb_insert_color(&mmo->offset, &obj->mmo.offsets);
spin_unlock(&obj->mmo.lock);
return mmo;
}
static struct i915_mmap_offset *
mmap_offset_attach(struct drm_i915_gem_object *obj,
enum i915_mmap_type mmap_type,
@ -496,20 +558,22 @@ mmap_offset_attach(struct drm_i915_gem_object *obj,
struct i915_mmap_offset *mmo;
int err;
mmo = lookup_mmo(obj, mmap_type);
if (mmo)
goto out;
mmo = kmalloc(sizeof(*mmo), GFP_KERNEL);
if (!mmo)
return ERR_PTR(-ENOMEM);
mmo->obj = obj;
mmo->dev = obj->base.dev;
mmo->file = file;
mmo->mmap_type = mmap_type;
drm_vma_node_reset(&mmo->vma_node);
err = drm_vma_offset_add(mmo->dev->vma_offset_manager, &mmo->vma_node,
obj->base.size / PAGE_SIZE);
err = drm_vma_offset_add(obj->base.dev->vma_offset_manager,
&mmo->vma_node, obj->base.size / PAGE_SIZE);
if (likely(!err))
goto out;
goto insert;
/* Attempt to reap some mmap space from dead objects */
err = intel_gt_retire_requests_timeout(&i915->gt, MAX_SCHEDULE_TIMEOUT);
@ -517,19 +581,17 @@ mmap_offset_attach(struct drm_i915_gem_object *obj,
goto err;
i915_gem_drain_freed_objects(i915);
err = drm_vma_offset_add(mmo->dev->vma_offset_manager, &mmo->vma_node,
obj->base.size / PAGE_SIZE);
err = drm_vma_offset_add(obj->base.dev->vma_offset_manager,
&mmo->vma_node, obj->base.size / PAGE_SIZE);
if (err)
goto err;
insert:
mmo = insert_mmo(obj, mmo);
GEM_BUG_ON(lookup_mmo(obj, mmap_type) != mmo);
out:
if (file)
drm_vma_node_allow(&mmo->vma_node, file);
spin_lock(&obj->mmo.lock);
list_add(&mmo->offset, &obj->mmo.offsets);
spin_unlock(&obj->mmo.lock);
return mmo;
err:

18
drivers/gpu/drm/i915/gem/i915_gem_object.c
View File

@ -63,7 +63,7 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
INIT_LIST_HEAD(&obj->lut_list);
spin_lock_init(&obj->mmo.lock);
INIT_LIST_HEAD(&obj->mmo.offsets);
obj->mmo.offsets = RB_ROOT;
init_rcu_head(&obj->rcu);
@ -100,8 +100,8 @@ void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
{
struct drm_i915_gem_object *obj = to_intel_bo(gem);
struct drm_i915_file_private *fpriv = file->driver_priv;
struct i915_mmap_offset *mmo, *mn;
struct i915_lut_handle *lut, *ln;
struct i915_mmap_offset *mmo;
LIST_HEAD(close);
i915_gem_object_lock(obj);
@ -117,14 +117,8 @@ void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
i915_gem_object_unlock(obj);
spin_lock(&obj->mmo.lock);
list_for_each_entry(mmo, &obj->mmo.offsets, offset) {
if (mmo->file != file)
continue;
spin_unlock(&obj->mmo.lock);
rbtree_postorder_for_each_entry_safe(mmo, mn, &obj->mmo.offsets, offset)
drm_vma_node_revoke(&mmo->vma_node, file);
spin_lock(&obj->mmo.lock);
}
spin_unlock(&obj->mmo.lock);
list_for_each_entry_safe(lut, ln, &close, obj_link) {
@ -203,12 +197,14 @@ static void __i915_gem_free_objects(struct drm_i915_private *i915,
i915_gem_object_release_mmap(obj);
list_for_each_entry_safe(mmo, mn, &obj->mmo.offsets, offset) {
rbtree_postorder_for_each_entry_safe(mmo, mn,
&obj->mmo.offsets,
offset) {
drm_vma_offset_remove(obj->base.dev->vma_offset_manager,
&mmo->vma_node);
kfree(mmo);
}
INIT_LIST_HEAD(&obj->mmo.offsets);
obj->mmo.offsets = RB_ROOT;
GEM_BUG_ON(atomic_read(&obj->bind_count));
GEM_BUG_ON(obj->userfault_count);

6
drivers/gpu/drm/i915/gem/i915_gem_object_types.h
View File

@ -71,13 +71,11 @@ enum i915_mmap_type {
};
struct i915_mmap_offset {
struct drm_device *dev;
struct drm_vma_offset_node vma_node;
struct drm_i915_gem_object *obj;
struct drm_file *file;
enum i915_mmap_type mmap_type;
struct list_head offset;
struct rb_node offset;
};
struct drm_i915_gem_object {
@ -137,7 +135,7 @@ struct drm_i915_gem_object {
struct {
spinlock_t lock; /* Protects access to mmo offsets */
struct list_head offsets;
struct rb_root offsets;
} mmo;
I915_SELFTEST_DECLARE(struct list_head st_link);