3.16.7-ckt18 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Chris Wilson <[email protected]> commit 51bc140431e233284660b1d22c47dec9ecdb521e upstream. 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 <[email protected]> Cc: Daniel Vetter <[email protected]> Cc: Kristian Høgsberg <[email protected]> Cc: Jesse Barnes <[email protected]> Cc: "Goel, Akash" <[email protected]> Cc: Michał Winiarski <[email protected]> Reviewed-by: Daniel Vetter <[email protected]> Signed-off-by: Jani Nikula <[email protected]> [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques <[email protected]> --- drivers/gpu/drm/i915/i915_gem_execbuffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 3a30133f93e8..ebce39a0d921 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -965,6 +965,7 @@ 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; @@ -973,7 +974,6 @@ i915_gem_execbuffer_move_to_active(struct list_head *vmas, i915_vma_move_to_active(vma, ring); if (obj->base.write_domain) { - obj->dirty = 1; obj->last_write_seqno = intel_ring_get_seqno(ring); /* check for potential scanout */ if (i915_gem_obj_ggtt_bound(obj) && -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
