On 2024-02-22 16:52, Guenter Roeck wrote: > 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. > That's interesting. Which --arch argument are you using to run the tests with QEMU? Thanks, Marco
