Hi Marco,
On 2/22/24 07:32, Marco Pagani wrote:
On 2024-02-18 16:49, Guenter Roeck wrote:
Hi,
On Thu, Nov 30, 2023 at 06:14:16PM +0100, Marco Pagani wrote:
This patch introduces an initial KUnit test suite for GEM objects
backed by shmem buffers.
Suggested-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Signed-off-by: Marco Pagani <marpagan@xxxxxxxxxx>
When running this in qemu, I get lots of warnings backtraces in the drm
core.
WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:327
WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:173
WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:385
WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:211
WARNING: CPU: 0 PID: 1345 at kernel/dma/mapping.c:194
WARNING: CPU: 0 PID: 1347 at drivers/gpu/drm/drm_gem_shmem_helper.c:429
WARNING: CPU: 0 PID: 1349 at drivers/gpu/drm/drm_gem_shmem_helper.c:445
It looks like dma_resv_assert_held() asserts each time it is executed.
The backtrace in kernel/dma/mapping.c is triggered by
if (WARN_ON_ONCE(!dev->dma_mask))
return 0;
in __dma_map_sg_attrs().
Is this a possible problem in the test code, or can it be caused by
some limitations or bugs in the qemu emulation ? If so, do you have any
thoughts or ideas what those limitations / bugs might be ?
Hi Guenter,
Thanks for reporting this issue. As you correctly noted, the warnings appear to
be caused by the dma_mask in the mock device being uninitialized. I'll send a
patch to fix it soon.
Thanks a lot for the update.
In this context, the TTM unit tests fail as well in qemu, with worse result:
It seems there is some bad cleanup after a failed test case, causing list
corruptions in the drm core and ultimately a crash. I don't know if this
is also caused by the missing dma_mask initialization.
Thanks,
Guenter
