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authorChris Wilson <chris@chris-wilson.co.uk>2020-09-15 10:14:17 +0100
committerRodrigo Vivi <rodrigo.vivi@intel.com>2020-09-30 14:24:23 -0400
commit922d369b2922b3bb8c72aadddbd7445e6dc1183a (patch)
tree0d429a3ca1e9ed4b74901f8432c298f2b3100239 /drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
parentba2ebf605d5f32a9be0f7b05d3174bbc501b83fe (diff)
drm/i915/gt: Clear the buffer pool age before use
If we create a new node, it is possible for the slab allocator to return us a recently freed node. If that node was just retired, it will retain the current jiffy as its node->age. There is then a miniscule window, where as that node is retired, it will appear on the free list with an incorrect age and be eligible for reuse by one thread, and then by a second thread as the correct node->age is written. Fixes: 06b73c2d0b65 ("drm/i915/gt: Delay taking the spinlock for grabbing from the buffer pool") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200915091417.4086-3-chris@chris-wilson.co.uk (cherry picked from commit 9bb34ff25c458a2a48fb61409df42f465ede37f8) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Diffstat (limited to 'drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c')
-rw-r--r--drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c b/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
index 4b7671ac5dca..104cb30e8c13 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_buffer_pool.c
@@ -134,6 +134,7 @@ static void pool_retire(struct i915_active *ref)
/* Return this object to the shrinker pool */
i915_gem_object_make_purgeable(node->obj);
+ GEM_BUG_ON(node->age);
spin_lock_irqsave(&pool->lock, flags);
list_add_rcu(&node->link, list);
WRITE_ONCE(node->age, jiffies ?: 1); /* 0 reserved for active nodes */
@@ -155,6 +156,7 @@ node_create(struct intel_gt_buffer_pool *pool, size_t sz)
if (!node)
return ERR_PTR(-ENOMEM);
+ node->age = 0;
node->pool = pool;
i915_active_init(&node->active, pool_active, pool_retire);