vLLM issue #38967: vLLM >= 0.18.0 segfaults in NCCL cuMemCreate with TP>1 on RTX 4090 (SM 89)

Reporter zhouliang5266, 2x RTX 4090 48GB (SM 89), vLLM 0.18.0, NCCL 2.27.5, openEuler 22.03 SP4. Only ONE independent reporter; the reporter later conceded he had not isolated the cause and suggested closing. Workarounds tried and reported as failing: NCCL_CUMEM=0 + NCCL_P2P_DISABLE=1, mp executor, larger --shm-size, VLLM_USE_V1=0 (unavailable, V0 removed in 0.18.0). SWAP TEST: same v0.18.0 + TP=2 works on two other identical machines, segfaults only on the third (cross-NUMA SYS topology) - so NOT a universal 4090 behaviour. Single report, unresolved. Verified 2026-10-10: Read issue '[Bug] vLLM >= 0.18.0 NCCL segfault (cuMemCreate) with TP>1 on RTX 4090 (SM 89)' (https://github.com/vllm-project/vllm/issues/38967); confirms bug report, environment details, workarounds tried, swap test results, and unresolved status.