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drm/gem: Add ww_acquire_ctx support to drm_gem_lru_scan()

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If the callback is going to have to attempt to grab more locks, it is
useful to have an ww_acquire_ctx to avoid locking order problems.

Why not use the drm_exec helper instead?  Mainly because (a) where
ww_acquire_init() is called is awkward, and (b) we don't really
need to retry after backoff, we can just move on to the next object.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Tested-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Antonino Maniscalco <antomani103@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/661463/
This commit is contained in:
Rob Clark 2025-06-29 13:12:46 -07:00 committed by Rob Clark
parent 471920ce25
commit 02070f0498
3 changed files with 30 additions and 18 deletions
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14
drivers/gpu/drm/drm_gem.c
View File

@ -1429,12 +1429,14 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail);
* @nr_to_scan: The number of pages to try to reclaim
* @remaining: The number of pages left to reclaim, should be initialized by caller
* @shrink: Callback to try to shrink/reclaim the object.
* @ticket: Optional ww_acquire_ctx context to use for locking
*/
unsigned long
drm_gem_lru_scan(struct drm_gem_lru *lru,
unsigned int nr_to_scan,
unsigned long *remaining,
bool (*shrink)(struct drm_gem_object *obj))
bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket),
struct ww_acquire_ctx *ticket)
{
struct drm_gem_lru still_in_lru;
struct drm_gem_object *obj;
@ -1467,17 +1469,20 @@ drm_gem_lru_scan(struct drm_gem_lru *lru,
*/
mutex_unlock(lru->lock);
if (ticket)
ww_acquire_init(ticket, &reservation_ww_class);
/*
* Note that this still needs to be trylock, since we can
* hit shrinker in response to trying to get backing pages
* for this obj (ie. while it's lock is already held)
*/
if (!dma_resv_trylock(obj->resv)) {
if (!ww_mutex_trylock(&obj->resv->lock, ticket)) {
*remaining += obj->size >> PAGE_SHIFT;
goto tail;
}
if (shrink(obj)) {
if (shrink(obj, ticket)) {
freed += obj->size >> PAGE_SHIFT;
/*
@ -1491,6 +1496,9 @@ drm_gem_lru_scan(struct drm_gem_lru *lru,
dma_resv_unlock(obj->resv);
if (ticket)
ww_acquire_fini(ticket);
tail:
drm_gem_object_put(obj);
mutex_lock(lru->lock);

24
drivers/gpu/drm/msm/msm_gem_shrinker.c
View File

@ -44,7 +44,7 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
}
static bool
purge(struct drm_gem_object *obj)
purge(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)
{
if (!is_purgeable(to_msm_bo(obj)))
return false;
@ -58,7 +58,7 @@ purge(struct drm_gem_object *obj)
}
static bool
evict(struct drm_gem_object *obj)
evict(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)
{
if (is_unevictable(to_msm_bo(obj)))
return false;
@ -79,21 +79,21 @@ wait_for_idle(struct drm_gem_object *obj)
}
static bool
active_purge(struct drm_gem_object *obj)
active_purge(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)
{
if (!wait_for_idle(obj))
return false;
return purge(obj);
return purge(obj, ticket);
}
static bool
active_evict(struct drm_gem_object *obj)
active_evict(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)
{
if (!wait_for_idle(obj))
return false;
return evict(obj);
return evict(obj, ticket);
}
static unsigned long
@ -102,7 +102,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
struct msm_drm_private *priv = shrinker->private_data;
struct {
struct drm_gem_lru *lru;
bool (*shrink)(struct drm_gem_object *obj);
bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket);
bool cond;
unsigned long freed;
unsigned long remaining;
@ -122,8 +122,9 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
continue;
stages[i].freed =
drm_gem_lru_scan(stages[i].lru, nr,
&stages[i].remaining,
stages[i].shrink);
&stages[i].remaining,
stages[i].shrink,
NULL);
nr -= stages[i].freed;
freed += stages[i].freed;
remaining += stages[i].remaining;
@ -164,7 +165,7 @@ msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan)
static const int vmap_shrink_limit = 15;
static bool
vmap_shrink(struct drm_gem_object *obj)
vmap_shrink(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket)
{
if (!is_vunmapable(to_msm_bo(obj)))
return false;
@ -192,7 +193,8 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
unmapped += drm_gem_lru_scan(lrus[idx],
vmap_shrink_limit - unmapped,
&remaining,
vmap_shrink);
vmap_shrink,
NULL);
}
*(unsigned long *)ptr += unmapped;

10
include/drm/drm_gem.h
View File

@ -560,10 +560,12 @@ void drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock);
void drm_gem_lru_remove(struct drm_gem_object *obj);
void drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj);
void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj);
unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru,
unsigned int nr_to_scan,
unsigned long *remaining,
bool (*shrink)(struct drm_gem_object *obj));
unsigned long
drm_gem_lru_scan(struct drm_gem_lru *lru,
unsigned int nr_to_scan,
unsigned long *remaining,
bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket),
struct ww_acquire_ctx *ticket);
int drm_gem_evict_locked(struct drm_gem_object *obj);