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>> while (!list_is_head(prev->next, &vm->done)) { >> bo_va = list_entry(prev->next, typeof(*bo_va), base.vm_status); >> - spin_unlock(&vm->status_lock); >> >> bo = bo_va->base.bo; >> if (bo) { >> + amdgpu_bo_ref(bo); >> + spin_unlock(&vm->status_lock); >> + >> ret = drm_exec_prepare_obj(exec, &bo->tbo.base, 1); > > Just for my understanding, there is a possibility that a bo is free after spin_unlock and we might be using a stale/NULL ptr of bo.  So we are taking a reference before releasing the lock to make > > sure the bo is valid. Now calling drm_exec_prepare_obj take a recount to make sure the bo is always from now on. Yes, exactly that. > Reviewed-by: Sunil Khatri Thanks! Christian. > >> + amdgpu_bo_unref(&bo); >> if (unlikely(ret)) >> return ret; >> + >> + spin_lock(&vm->status_lock); >> } >> - spin_lock(&vm->status_lock); >> prev = prev->next; >> } >> spin_unlock(&vm->status_lock);