From 677feac291c1ea7f0b84c6e499e858d440b96c7b Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 19 Dec 2012 14:33:45 +0100 Subject: [PATCH] drm/i915: optionally disable shrinker lock stealing commit 5774506f157a91400c587b85d1ce4de56f0d32f6 Author: Chris Wilson Date: Wed Nov 21 13:04:04 2012 +0000 drm/i915: Borrow our struct_mutex for the direct reclaim added a nice trick to steal the struct_mutex lock in the shrinker if it's the current task holding it. But this also caused the requirement that every place which allocates memory needs to be careful about the gem state of objects, since the shrinker could have pulled the rug out from under it. We've usually solved this by carefully preallocating things or ensure that buffers are pinned already. But the shrinker also reaps mmap offset, so allocating those needs to be careful, too. Now that code has been factored out into some common helpers, so either we have fragile code depending upon the common helper not doing something we don't want it to do. Or we need to reimplement the mmap offset creation and so also leak implementation details into our code. Since this all results in leaky abstraction, cop out by disabling the lock borrowing trick while calling down into the helpers. That way our craziness is nicely confined to files in drm/i915. v2: Split out the change to create_mmap_offset as request by Chris Wilson. Cc: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Chris Wilson Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_drv.h | 1 + drivers/gpu/drm/i915/i915_gem.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 1a4c3a1c111f..ed3059575576 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -780,6 +780,7 @@ typedef struct drm_i915_private { struct i915_hw_ppgtt *aliasing_ppgtt; struct shrinker inactive_shrinker; + bool shrinker_no_lock_stealing; /** * List of objects currently involved in rendering. diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 5feda1f67042..ad6f321083a6 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4380,6 +4380,9 @@ i915_gem_inactive_shrink(struct shrinker *shrinker, struct shrink_control *sc) if (!mutex_is_locked_by(&dev->struct_mutex, current)) return 0; + if (dev_priv->mm.shrinker_no_lock_stealing) + return 0; + unlock = false; } -- 2.39.2