From e9f24d5fb7cf3628b195b18ff3ac4e37937ceeae Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Mon, 5 Oct 2015 13:26:36 +0100 Subject: [PATCH] drm/i915: Clean up associated VMAs on context destruction Prevent leaking VMAs and PPGTT VMs when objects are imported via flink. Scenario is that any VMAs created by the importer will be left dangling after the importer exits, or destroys the PPGTT context with which they are associated. This is caused by object destruction not running when the importer closes the buffer object handle due the reference held by the exporter. This also leaks the VM since the VMA has a reference on it. In practice these leaks can be observed by stopping and starting the X server on a kernel with fbcon compiled in. Every time X server exits another VMA will be leaked against the fbcon's frame buffer object. Also on systems where flink buffer sharing is used extensively, like Android, this leak has even more serious consequences. This version is takes a general approach from the earlier work by Rafael Barbalho (drm/i915: Clean-up PPGTT on context destruction) and tries to incorporate the subsequent discussion between Chris Wilson and Daniel Vetter. v2: Removed immediate cleanup on object retire - it was causing a recursive VMA unbind via i915_gem_object_wait_rendering. And it is in fact not even needed since by definition context cleanup worker runs only after the last context reference has been dropped, hence all VMAs against the VM belonging to the context are already on the inactive list. v3: Previous version could deadlock since VMA unbind waits on any rendering on an object to complete. Objects can be busy in a different VM which would mean that the cleanup loop would do the wait with the struct mutex held. This is an even simpler approach where we just unbind VMAs without waiting since we know all VMAs belonging to this VM are idle, and there is nothing in flight, at the point context destructor runs. v4: Double underscore prefix for __915_vma_unbind_no_wait and a commit message typo fix. (Michel Thierry) Note that this is just a partial/interim fix since we have a bit a fundamental issue with cleaning up, e.g. https://bugs.freedesktop.org/show_bug.cgi?id=87729 Signed-off-by: Tvrtko Ursulin Testcase: igt/gem_ppgtt.c/flink-and-exit-vma-leak Reviewed-by: Michel Thierry Cc: Daniel Vetter Cc: Chris Wilson Cc: Rafael Barbalho Cc: Michel Thierry [danvet: Add a note that this isn't everything.] Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_drv.h | 5 +++++ drivers/gpu/drm/i915/i915_gem.c | 20 ++++++++++++++++---- drivers/gpu/drm/i915/i915_gem_context.c | 24 ++++++++++++++++++++++++ 3 files changed, 45 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 35bf5cb..c93f9a1 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2839,6 +2839,11 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj, int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level, u32 flags); int __must_check i915_vma_unbind(struct i915_vma *vma); +/* + * BEWARE: Do not use the function below unless you can _absolutely_ + * _guarantee_ VMA in question is _not in use_ anywhere. + */ +int __must_check __i915_vma_unbind_no_wait(struct i915_vma *vma); int i915_gem_object_put_pages(struct drm_i915_gem_object *obj); void i915_gem_release_all_mmaps(struct drm_i915_private *dev_priv); void i915_gem_release_mmap(struct drm_i915_gem_object *obj); diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index f0cfbb9..52642af 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3208,7 +3208,7 @@ static void i915_gem_object_finish_gtt(struct drm_i915_gem_object *obj) old_write_domain); } -int i915_vma_unbind(struct i915_vma *vma) +static int __i915_vma_unbind(struct i915_vma *vma, bool wait) { struct drm_i915_gem_object *obj = vma->obj; struct drm_i915_private *dev_priv = obj->base.dev->dev_private; @@ -3227,9 +3227,11 @@ int i915_vma_unbind(struct i915_vma *vma) BUG_ON(obj->pages == NULL); - ret = i915_gem_object_wait_rendering(obj, false); - if (ret) - return ret; + if (wait) { + ret = i915_gem_object_wait_rendering(obj, false); + if (ret) + return ret; + } if (i915_is_ggtt(vma->vm) && vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL) { @@ -3274,6 +3276,16 @@ int i915_vma_unbind(struct i915_vma *vma) return 0; } +int i915_vma_unbind(struct i915_vma *vma) +{ + return __i915_vma_unbind(vma, true); +} + +int __i915_vma_unbind_no_wait(struct i915_vma *vma) +{ + return __i915_vma_unbind(vma, false); +} + int i915_gpu_idle(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index 74aa0c9..680b4c9 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -133,6 +133,23 @@ static int get_context_size(struct drm_device *dev) return ret; } +static void i915_gem_context_clean(struct intel_context *ctx) +{ + struct i915_hw_ppgtt *ppgtt = ctx->ppgtt; + struct i915_vma *vma, *next; + + if (WARN_ON_ONCE(!ppgtt)) + return; + + WARN_ON(!list_empty(&ppgtt->base.active_list)); + + list_for_each_entry_safe(vma, next, &ppgtt->base.inactive_list, + mm_list) { + if (WARN_ON(__i915_vma_unbind_no_wait(vma))) + break; + } +} + void i915_gem_context_free(struct kref *ctx_ref) { struct intel_context *ctx = container_of(ctx_ref, typeof(*ctx), ref); @@ -142,6 +159,13 @@ void i915_gem_context_free(struct kref *ctx_ref) if (i915.enable_execlists) intel_lr_context_free(ctx); + /* + * This context is going away and we need to remove all VMAs still + * around. This is to handle imported shared objects for which + * destructor did not run when their handles were closed. + */ + i915_gem_context_clean(ctx); + i915_ppgtt_put(ctx->ppgtt); if (ctx->legacy_hw_ctx.rcs_state) -- 2.7.4