On Fri, May 04, 2018 at 09:03:32AM +0300, Tapani Pälli wrote:
> Hi Nanley;
>
Hey Tapani,
> On 05/03/2018 10:03 PM, Nanley Chery wrote:
> > Before this patch, if we failed to initialize an MCS buffer, we'd
> > end up in a state in which the miptree thinks it has an MCS buffer,
> > but doesn't. We also leaked the clear_color_bo if it existed.
> >
> > With this patch, we now free the miptree aux buffer resources and let
> > intel_miptree_alloc_mcs() know that the MCS buffer no longer exists.
>
> I triggered this by forcing the failure (by inserting 1 instead unlikely(map
> ==NULL) to mcs buffer map condition) and following happens currently:
Thanks for testing this! It'd be great if we could have a piglit test
that would trigger this case for us, but it's not clear to me what that
would look like.
>
> --- 8< ---
> Failed to map mcs buffer into GTT
> deqp-egl: ../src/intel/blorp/blorp_clear.c:313: blorp_fast_clear: Assertion
> `start_layer + num_layers <= MAX2(surf->aux_surf->logical_level0_px.depth >>
> level, surf->aux_surf->logical_level0_px.array_len)' failed.
> Aborted (core dumped)
I can confirm a similar assertion with piglit's
arb_clear_texture-multisample. What's happening here is that
blorp_fast_clear is receiving garbage aux surfaces, which causes it to
randomly trigger different assertions.
> --- 8< ---
>
> However even with this fix it seems we will end up in same or similar case
> (segfault happening in do_single_blorp_clear):
>
> --- 8< ---
> Failed to map mcs buffer into GTT
> Segmentation fault (core dumped)
> --- 8< ---
>
> Test case used was:
> dEQP-EGL.functional.color_clears.single_context.gles2.rgba8888_window
This is interesting. What happens here is that we enter
do_single_blorp_clear() with irb->mt == NULL and we segfault at:
if (irb->Base.Base.Format != irb->mt->format)
It looks like some callers of intel_miptree_create() don't handle
failure well. Maybe they should throw an EGL error? Here's the backtrace
from the failed init:
#0 intel_miptree_init_mcs
#1 intel_miptree_alloc_mcs
#2 intel_miptree_alloc_aux
#3 intel_miptree_create
#4 intel_miptree_create_for_renderbuffer
#5 intel_update_winsys_renderbuffer_miptree
#6 intel_update_image_buffer
#7 intel_update_image_buffers
#8 intel_update_renderbuffers
#9 intel_prepare_render
#10 intelMakeCurrent
#11 driBindContext
#12 ?? () from /usr/lib/libEGL_mesa.so.0
#13 eglMakeCurrent
#14 ?? () from /usr/lib/libEGL.so
#15 ?? () from /usr/lib/libEGL.so
#16 deqp::egl::SingleThreadColorClearCase::executeForContexts
#17 deqp::egl::MultiContextRenderCase::executeForSurface
#18 deqp::egl::RenderCase::executeForConfig
#19 deqp::egl::SimpleConfigCase::iterate
#20 tcu::TestSessionExecutor::iterateTestCase
#21 tcu::TestSessionExecutor::iterate
#22 tcu::App::iterate
#23 main (argc=<optimized out>, argv=<optimized out>)
>
>
> Are we expected to survive without mcs?
I think it depends. Once we determine that we can enable MCS for a
miptree, we require that the aux buffer exist in order to successfully
create the miptree. In GL, if we can't successfully create a miptree, we
can throw a GL_OUT_OF_MEMORY error, and have mostly undefined behavior
for the rest of our existence. In EGL however, I think we can throw an
error that's not EGL_BAD_CONTEXT and carry on.
-Nanley
>
>
> > Cc: <mesa-sta...@lists.freedesktop.org>
> > ---
> > src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 14 +++++++-------
> > 1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > index b9a564552df..377efae32c9 100644
> > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > @@ -1658,7 +1658,7 @@ intel_miptree_copy_teximage(struct brw_context *brw,
> > intel_obj->needs_validate = true;
> > }
> > -static void
> > +static bool
> > intel_miptree_init_mcs(struct brw_context *brw,
> > struct intel_mipmap_tree *mt,
> > int init_value)
> > @@ -1678,13 +1678,14 @@ intel_miptree_init_mcs(struct brw_context *brw,
> > void *map = brw_bo_map(brw, mt->aux_buf->bo, MAP_WRITE | MAP_RAW);
> > if (unlikely(map == NULL)) {
> > fprintf(stderr, "Failed to map mcs buffer into GTT\n");
> > - brw_bo_unreference(mt->aux_buf->bo);
> > - free(mt->aux_buf);
> > - return;
> > + intel_miptree_aux_buffer_free(mt->aux_buf);
> > + mt->aux_buf = NULL;
> > + return false;
> > }
> > void *data = map;
> > memset(data, init_value, mt->aux_buf->size);
> > brw_bo_unmap(mt->aux_buf->bo);
> > + return true;
> > }
> > static struct intel_miptree_aux_buffer *
> > @@ -1764,15 +1765,14 @@ intel_miptree_alloc_mcs(struct brw_context *brw,
> > const uint32_t alloc_flags = 0;
> > mt->aux_buf = intel_alloc_aux_buffer(brw, "mcs-miptree",
> > &temp_mcs_surf, alloc_flags, mt);
> > - if (!mt->aux_buf) {
> > + if (!mt->aux_buf ||
> > + !intel_miptree_init_mcs(brw, mt, 0xFF)) {
> > free(aux_state);
> > return false;
> > }
> > mt->aux_state = aux_state;
> > - intel_miptree_init_mcs(brw, mt, 0xFF);
> > -
> > return true;
> > }
> >
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