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. Marco
