A nested dma_resv_reserve_fences(1) will not reserve slot from the
2nd call onwards and folowing dma_resv_add_fence() might hit the
"BUG_ON(fobj->num_fences >= fobj->max_fences)" check.
I915 hit above nested dma_resv case in ttm_bo_handle_move_mem() with
async unbind:
dma_resv_reserve_fences() from --> ttm_bo_handle_move_mem()
dma_resv_reserve_fences() from --> i915_vma_unbind_async()
dma_resv_add_fence() from --> i915_vma_unbind_async()
dma_resv_add_fence() from -->ttm_bo_move_accel_cleanup()
Resolve this by adding an extra fence in i915_vma_unbind_async().
Suggested-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_vma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 7d044888ac33..5ac4c1c2403c 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -2149,7 +2149,7 @@ int i915_vma_unbind_async(struct i915_vma *vma, bool trylock_vm)
if (!obj->mm.rsgt)
return -EBUSY;
- err = dma_resv_reserve_fences(obj->base.resv, 1);
+ err = dma_resv_reserve_fences(obj->base.resv, 2);
if (err)
return -EBUSY;
--
2.38.0
