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Nirmoy Das authored
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: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Fixes: 2f6b90da ("drm/i915: Use vma resources for async unbinding")
Cc: <stable@vger.kernel.org> # v5.18+
Signed-off-by: default avatarNirmoy Das <nirmoy.das@intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Signed-off-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221223092011.11657-1-nirmoy.das@intel.com


(cherry picked from commit 4f0755c2)
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
476fdcda
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