From: José Expósito <[email protected]>
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: 93032ae634d4 ("drm/test: add a test suite for GEM objects backed by
shmem")
Closes: https://datawarehouse.cki-project.org/issue/5345
Closes: https://datawarehouse.cki-project.org/issue/3184
Assisted-by: Claude:claude-4.6-opus
Signed-off-by: José Expósito <[email protected]>
---
v2:
- Move fix to drm_gem_shmem_test_init() (Thomas Zimmermann)
- Link to v1:
https://lore.kernel.org/dri-devel/[email protected]/
---
drivers/gpu/drm/tests/drm_gem_shmem_test.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/tests/drm_gem_shmem_test.c
b/drivers/gpu/drm/tests/drm_gem_shmem_test.c
index 44a190109249..6e6b4f4902c2 100644
--- a/drivers/gpu/drm/tests/drm_gem_shmem_test.c
+++ b/drivers/gpu/drm/tests/drm_gem_shmem_test.c
@@ -94,14 +94,6 @@ static void drm_gem_shmem_test_obj_create_private(struct
kunit *test)
sg_init_one(sgt->sgl, buf, TEST_SIZE);
- /*
- * Set the DMA mask to 64-bits and map the sgtables
- * otherwise drm_gem_shmem_free will cause a warning
- * on debug kernels.
- */
- ret = dma_set_mask(drm_dev->dev, DMA_BIT_MASK(64));
- KUNIT_ASSERT_EQ(test, ret, 0);
-
ret = dma_map_sgtable(drm_dev->dev, sgt, DMA_BIDIRECTIONAL, 0);
KUNIT_ASSERT_EQ(test, ret, 0);
@@ -352,11 +344,20 @@ static int drm_gem_shmem_test_init(struct kunit *test)
{
struct device *dev;
struct drm_device *drm_dev;
+ int ret;
/* Allocate a parent device */
dev = drm_kunit_helper_alloc_device(test);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+ /*
+ * Set the DMA mask to 64-bits and map the sgtables
+ * otherwise drm_gem_shmem_free will cause a warning
+ * on debug kernels.
+ */
+ ret = dma_set_mask(dev, DMA_BIT_MASK(64));
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
/*
* The DRM core will automatically initialize the GEM core and create
* a DRM Memory Manager object which provides an address space pool
--
2.54.0
