From 2826d447fbd60e6a05e53d5f918bceb8c04e315c Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 26 Jul 2022 16:48:44 +0200 Subject: [PATCH] drm/i915/gem: Remove shared locking on freeing objects The obj->base.resv may be shared across many objects, some of which may still be live and locked, preventing objects from being freed indefintely. We could individualise the lock during the free, or rely on a freed object having no contention and being able to immediately free the pages it owns. References: https://gitlab.freedesktop.org/drm/intel/-/issues/6469 Fixes: be7612fd6665 ("drm/i915: Require object lock when freeing pages during destruction") Fixes: 6cb12fbda1c2 ("drm/i915: Use trylock instead of blocking lock for __i915_gem_free_objects.") Cc: # v5.17+ Signed-off-by: Chris Wilson Tested-by: Nirmoy Das Acked-by: Nirmoy Das Signed-off-by: Nirmoy Das Reviewed-by: Matthew Auld Signed-off-by: Matthew Auld Link: https://patchwork.freedesktop.org/patch/msgid/20220726144844.18429-1-nirmoy.das@intel.com (cherry picked from commit 7dd5c56531eb03696acdb17774721de5ef481c0b) Signed-off-by: Rodrigo Vivi --- drivers/gpu/drm/i915/gem/i915_gem_object.c | 16 ++++------------ drivers/gpu/drm/i915/i915_drv.h | 4 ++-- 2 files changed, 6 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c index ccec405..389e9f1 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c @@ -268,7 +268,7 @@ static void __i915_gem_object_free_mmaps(struct drm_i915_gem_object *obj) */ void __i915_gem_object_pages_fini(struct drm_i915_gem_object *obj) { - assert_object_held(obj); + assert_object_held_shared(obj); if (!list_empty(&obj->vma.list)) { struct i915_vma *vma; @@ -331,15 +331,7 @@ static void __i915_gem_free_objects(struct drm_i915_private *i915, continue; } - if (!i915_gem_object_trylock(obj, NULL)) { - /* busy, toss it back to the pile */ - if (llist_add(&obj->freed, &i915->mm.free_list)) - queue_delayed_work(i915->wq, &i915->mm.free_work, msecs_to_jiffies(10)); - continue; - } - __i915_gem_object_pages_fini(obj); - i915_gem_object_unlock(obj); __i915_gem_free_object(obj); /* But keep the pointer alive for RCU-protected lookups */ @@ -359,7 +351,7 @@ void i915_gem_flush_free_objects(struct drm_i915_private *i915) static void __i915_gem_free_work(struct work_struct *work) { struct drm_i915_private *i915 = - container_of(work, struct drm_i915_private, mm.free_work.work); + container_of(work, struct drm_i915_private, mm.free_work); i915_gem_flush_free_objects(i915); } @@ -391,7 +383,7 @@ static void i915_gem_free_object(struct drm_gem_object *gem_obj) */ if (llist_add(&obj->freed, &i915->mm.free_list)) - queue_delayed_work(i915->wq, &i915->mm.free_work, 0); + queue_work(i915->wq, &i915->mm.free_work); } void __i915_gem_object_flush_frontbuffer(struct drm_i915_gem_object *obj, @@ -745,7 +737,7 @@ bool i915_gem_object_needs_ccs_pages(struct drm_i915_gem_object *obj) void i915_gem_init__objects(struct drm_i915_private *i915) { - INIT_DELAYED_WORK(&i915->mm.free_work, __i915_gem_free_work); + INIT_WORK(&i915->mm.free_work, __i915_gem_free_work); } void i915_objects_module_exit(void) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index d25647b..086bbe8 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -247,7 +247,7 @@ struct i915_gem_mm { * List of objects which are pending destruction. */ struct llist_head free_list; - struct delayed_work free_work; + struct work_struct free_work; /** * Count of objects pending destructions. Used to skip needlessly * waiting on an RCU barrier if no objects are waiting to be freed. @@ -1378,7 +1378,7 @@ static inline void i915_gem_drain_freed_objects(struct drm_i915_private *i915) * armed the work again. */ while (atomic_read(&i915->mm.free_count)) { - flush_delayed_work(&i915->mm.free_work); + flush_work(&i915->mm.free_work); flush_delayed_work(&i915->bdev.wq); rcu_barrier(); } -- 2.7.4