From: Nirmoy Das nirmoy.das@intel.com
commit 476fdcdaaae7b06c780cdfc234c704107f16c529 upstream.
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@linux.intel.com Fixes: 2f6b90da9192 ("drm/i915: Use vma resources for async unbinding") Cc: stable@vger.kernel.org # v5.18+ Signed-off-by: Nirmoy Das nirmoy.das@intel.com Reviewed-by: Matthew Auld matthew.auld@intel.com Signed-off-by: Matthew Auld matthew.auld@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20221223092011.11657-1-nirmoy.... (cherry picked from commit 4f0755c2faf7388616109717facc5bbde6850e60) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/i915/i915_vma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -2114,7 +2114,7 @@ int i915_vma_unbind_async(struct i915_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;