Am 14.04.21 um 08:46 schrieb Felix Kuehling:
amdgpu_ttm_tt_unpopulate can be called during bo_destroy. The dmabuf->resv
must not be held by the caller or dma_buf_detach will deadlock. This is
probably not the right fix. I get a recursive lock warning with the
reservation held in ttm_bo_release. Should unmap_attachment move to
backend_unbind instead?
Yes probably, but I'm really wondering if we should call unpopulate
without holding the reservation lock.
Christian.
Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 936b3cfdde55..257750921eed 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1216,9 +1216,22 @@ static void amdgpu_ttm_tt_unpopulate(struct ttm_device *bdev,
if (ttm->sg && gtt->gobj->import_attach) {
struct dma_buf_attachment *attach;
+ bool locked;
attach = gtt->gobj->import_attach;
+ /* FIXME: unpopulate can be called during bo_destroy.
+ * The dmabuf->resv must not be held by the caller or
+ * dma_buf_detach will deadlock. This is probably not
+ * the right fix. I get a recursive lock warning with the
+ * reservation held in ttm_bo_releas.. Should
+ * unmap_attachment move to backend_unbind instead?
+ */
+ locked = dma_resv_is_locked(attach->dmabuf->resv);
+ if (!locked)
+ dma_resv_lock(attach->dmabuf->resv, NULL);
dma_buf_unmap_attachment(attach, ttm->sg, DMA_BIDIRECTIONAL);
+ if (!locked)
+ dma_resv_unlock(attach->dmabuf->resv);
ttm->sg = NULL;
return;
}
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