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b04a248cfa
drm_gem_shmem_test_purge [1] and drm_gem_shmem_test_get_pages_sgt [2]
intermittently fail on ppc64le and s390x CI systems with a DMA address
overflow:
DMA addr 0x0000000100307000+4096 overflow (mask ffffffff, bus limit 0)
WARNING: kernel/dma/direct.h:114 dma_direct_map_sg+0x778/0x920
drm_gem_shmem_test_purge: ASSERTION FAILED at
drivers/gpu/drm/tests/drm_gem_shmem_test.c:330
Expected sgt is not error, but is: -5
The call chain leading to the failure is:
drm_gem_shmem_test_purge() / drm_gem_shmem_test_get_pages_sgt()
drm_gem_shmem_get_pages_sgt()
drm_gem_shmem_get_pages_sgt_locked() [drm_gem_shmem_helper.c]
dma_map_sgtable() [mapping.c]
__dma_map_sg_attrs()
dma_direct_map_sg() [direct.c]
dma_direct_map_phys() [kernel/dma/direct.h]
dma_capable() Checks addr against DMA mask
-> FAILS: addr > 0xFFFFFFFF
The root cause is that KUnit devices are initialized with a 32-bit DMA
mask (DMA_BIT_MASK(32)) in lib/kunit/device.c. On ppc64le and s390x
systems with physical memory above 4GB, page allocations can land at
addresses that exceed this mask. When drm_gem_shmem_get_pages_sgt()
attempts to DMA-map these pages via dma_map_sgtable(), the DMA layer
rejects the mapping because the physical address overflows the 32-bit
mask.
The failure is intermittent because pages may or may not be allocated
above 4GB on any given run depend on memory pressure.
Fix by setting a 64-bit DMA mask on the device before calling
drm_gem_shmem_get_pages_sgt() for all tests, following the same pattern
already used in drm_gem_shmem_test_obj_create_private().
[1] https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/2643976103/test_s390x/15128551935/artifacts/jobwatch/logs/recipes/21561049/tasks/220716793/results/1014626315/logs/dmesg.log
[2] https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/2643976103/test_ppc64le/15128551933/artifacts/jobwatch/logs/recipes/21561041/tasks/220716705/results/1014628163/logs/dmesg.log
Fixes:
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History
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