On Fri, Nov 09, 2012 at 08:58:50AM +0000, Chris Wilson wrote:
> In the circumstances that the shrinker is allowed to steal the mutex
> in order to reap pages, we need to be careful to prevent it operating on
> the current object and shooting ourselves in the foot.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Ok, I this is definitely the major one that I've thought of, but I think
I've found another place that need a similar treatment:
i915_gem_fault: In between bind_to_gtt and vm_insert_pfn we have a call to
get_fence, which might potentially call kmalloc due to a pending request.
I know, it's highly unlikely that this will ever matter, but I think if we
braket this with a pin/unpin, it will nicely serve as a reminder where to
reserve/unreserve and object, in case we ever switch to a per-object
locking scheme.
Otherwise I can't poke holes into this any more ...
Cheers, Daniel
> ---
> drivers/gpu/drm/i915/i915_gem.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 159dca5..f225583 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3091,6 +3091,8 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
> if (ret)
> return ret;
>
> + i915_gem_object_pin_pages(obj);
> +
> search_free:
> if (map_and_fenceable)
> free_space =
> @@ -3121,14 +3123,17 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
> obj->cache_level,
> map_and_fenceable,
> nonblocking);
> - if (ret)
> + if (ret) {
> + i915_gem_object_unpin_pages(obj);
> return ret;
> + }
>
> goto search_free;
> }
> if (WARN_ON(!i915_gem_valid_gtt_space(dev,
> obj->gtt_space,
> obj->cache_level))) {
> + i915_gem_object_unpin_pages(obj);
> drm_mm_put_block(obj->gtt_space);
> obj->gtt_space = NULL;
> return -EINVAL;
> @@ -3137,6 +3142,7 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
>
> ret = i915_gem_gtt_prepare_object(obj);
> if (ret) {
> + i915_gem_object_unpin_pages(obj);
> drm_mm_put_block(obj->gtt_space);
> obj->gtt_space = NULL;
> return ret;
> @@ -3159,6 +3165,7 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
>
> obj->map_and_fenceable = mappable && fenceable;
>
> + i915_gem_object_unpin_pages(obj);
> trace_i915_gem_object_bind(obj, map_and_fenceable);
> i915_gem_verify_gtt(dev);
> return 0;
> --
> 1.7.10.4
>
> _______________________________________________
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> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
