[Intel-gfx] [PATCH 1/2] drm/i915/gem: Taint all shrinkable object locks

Chris Wilson chris at chris-wilson.co.uk
Fri May 29 18:32:03 UTC 2020

If we declare that an object type is shrinkable (any that we can reclaim
to recover system pages), make sure we taint the object mutex so that
lockdep expects us to use it within fs_reclaim. lockdep will then
complain the first time we try to allocate while holding the plain
mutex, as doing so invites potential recursion.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
 drivers/gpu/drm/i915/gem/i915_gem_object.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 99356c00c19e..21635dd415a3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -72,6 +72,10 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
 	obj->mm.madv = I915_MADV_WILLNEED;
 	INIT_RADIX_TREE(&obj->mm.get_page.radix, GFP_KERNEL | __GFP_NOWARN);
+	if (IS_ENABLED(CONFIG_LOCKDEP) && i915_gem_object_is_shrinkable(obj))
+		i915_gem_shrinker_taints_mutex(to_i915(obj->base.dev),
+					       &obj->mm.lock);

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