From: Chris Wilson Date: Mon, 31 Aug 2015 14:10:39 +0000 (+0100) Subject: drm/i915: Always mark the object as dirty when used by the GPU X-Git-Tag: firefly_0821_release~176^2~1083^2~2^2~7 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=51bc140431e233284660b1d22c47dec9ecdb521e;p=firefly-linux-kernel-4.4.55.git drm/i915: Always mark the object as dirty when used by the GPU There have been many hard to track down bugs whereby userspace forgot to flag a write buffer and then cause graphics corruption or a hung GPU when that buffer was later purged under memory pressure (as the buffer appeared clean, its pages would have been evicted rather than preserved and any changes more recent than in the backing storage would be lost). In retrospect this is a rare optimisation against memory pressure, already the slow path. If we always mark the buffer as dirty when accessed by the GPU, anything not used can still be evicted cheaply (ideal behaviour for mark-and-sweep eviction) but we do not run the risk of corruption. For correct read serialisation, userspace still has to notify when the GPU writes to an object. However, there are certain situations under which userspace may wish to tell white lies to the kernel... Signed-off-by: Chris Wilson Cc: Daniel Vetter Cc: Kristian Høgsberg Cc: Jesse Barnes Cc: "Goel, Akash" Cc: Michał Winiarski Cc: stable@vger.kernel.org Reviewed-by: Daniel Vetter Signed-off-by: Jani Nikula --- diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 923a3c4bf0b7..a953d4975b8c 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -1032,6 +1032,7 @@ i915_gem_execbuffer_move_to_active(struct list_head *vmas, u32 old_read = obj->base.read_domains; u32 old_write = obj->base.write_domain; + obj->dirty = 1; /* be paranoid */ obj->base.write_domain = obj->base.pending_write_domain; if (obj->base.write_domain == 0) obj->base.pending_read_domains |= obj->base.read_domains; @@ -1039,7 +1040,6 @@ i915_gem_execbuffer_move_to_active(struct list_head *vmas, i915_vma_move_to_active(vma, req); if (obj->base.write_domain) { - obj->dirty = 1; i915_gem_request_assign(&obj->last_write_req, req); intel_fb_obj_invalidate(obj, ORIGIN_CS);