Note that just because we have n == MAX elements left, does not imply that there are only MAX elements left in the scatterlist and so we may not be on the last chain, and the nth element may in fact be a chain ptr.
This is exercised by the improved hangman tests and the gem_exec_big test in i-g-t. This regression has been introduced in commit 9da3da660d8c19a54f6e93361d147509be3fff84 Author: Chris Wilson <[email protected]> Date: Fri Jun 1 15:20:22 2012 +0100 drm/i915: Replace the array of pages with a scatterlist v2: KISS, replace the direct lookup with a for_each_sg() [danvet] v3: Try to be clever again. Signed-off-by: Chris Wilson <[email protected]> --- drivers/gpu/drm/i915/i915_drv.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index d2dda78..babe43d 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1383,9 +1383,14 @@ int __must_check i915_gem_object_get_pages(struct drm_i915_gem_object *obj); static inline struct page *i915_gem_object_get_page(struct drm_i915_gem_object *obj, int n) { struct scatterlist *sg = obj->pages->sgl; - while (n >= SG_MAX_SINGLE_ALLOC) { + int nents = obj->pages->nents; + while (nents > SG_MAX_SINGLE_ALLOC) { + if (n < SG_MAX_SINGLE_ALLOC - 1) + break; + sg = sg_chain_ptr(sg + SG_MAX_SINGLE_ALLOC - 1); n -= SG_MAX_SINGLE_ALLOC - 1; + nents -= SG_MAX_SINGLE_ALLOC - 1; } return sg_page(sg+n); } -- 1.7.10.4 _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
