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vllm - 💡(How to fix) Fix [Bug]: ZeroDivisionError in deepgemm_post_process_fp8_weight_block when loading FP8 model with TP=16 on dual-node H20

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Error Message

(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] Traceback (most recent call last): (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/v1/executor/multiproc_executor.py", line 837, in worker_main (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] worker = WorkerProc(*args, **kwargs) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] return func(*args, **kwargs) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ^^^^^^^^^^^^^^^^^^^^^ (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/v1/executor/multiproc_executor.py", line 619, in init (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] self.worker.load_model() (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/v1/worker/gpu_worker.py", line 345, in load_model (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] self.model_runner.load_model(load_dummy_weights=load_dummy_weights) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] return func(*args, **kwargs) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ^^^^^^^^^^^^^^^^^^^^^ (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/v1/worker/gpu_model_runner.py", line 4992, in load_model (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] self.model = model_loader.load_model( (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ^^^^^^^^^^^^^^^^^^^^^^^^ (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] return func(*args, **kwargs) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ^^^^^^^^^^^^^^^^^^^^^ (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/model_loader/base_loader.py", line 80, in load_model (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] process_weights_after_loading(model, model_config, target_device) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/model_loader/utils.py", line 111, in process_weights_after_loading (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] quant_method.process_weights_after_loading(module) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/layers/quantization/fp8.py", line 435, in process_weights_after_loading (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] self.fp8_linear.process_weights_after_loading(layer) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/kernels/linear/scaled_mm/flashinfer.py", line 175, in process_weights_after_loading (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] self.fallback.process_weights_after_loading(layer) (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/kernels/linear/scaled_mm/deep_gemm.py", line 96, in process_weights_after_loading (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] dg_weight, dg_weight_scale = deepgemm_post_process_fp8_weight_block( (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/layers/quantization/utils/fp8_utils.py", line 1036, in deepgemm_post_process_fp8_weight_block (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] r = wq.size(0) // g (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ~~~~~~~~~~~^^~~ (Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ZeroDivisionError: integer division or modulo by zero

Fix Action

Fix / Workaround

============================== CPU Info

Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Address sizes: 46 bits physical, 57 bits virtual Byte Order: Little Endian CPU(s): 224 On-line CPU(s) list: 0-223 Vendor ID: GenuineIntel Model name: Intel(R) Xeon(R) Platinum 8480+ CPU family: 6 Model: 143 Thread(s) per core: 2 Core(s) per socket: 56 Socket(s): 2 Stepping: 8 CPU max MHz: 3800.0000 CPU min MHz: 800.0000 BogoMIPS: 4000.00 Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cat_l2 cdp_l3 invpcid_single intel_ppin cdp_l2 ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb intel_pt avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local split_lock_detect avx_vnni avx512_bf16 wbnoinvd dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req avx512vbmi umip pku ospke waitpkg avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg tme avx512_vpopcntdq la57 rdpid bus_lock_detect cldemote movdiri movdir64b enqcmd fsrm md_clear serialize tsxldtrk pconfig arch_lbr amx_bf16 avx512_fp16 amx_tile amx_int8 flush_l1d arch_capabilities Virtualization: VT-x L1d cache: 5.3 MiB (112 instances) L1i cache: 3.5 MiB (112 instances) L2 cache: 224 MiB (112 instances) L3 cache: 210 MiB (2 instances) NUMA node(s): 2 NUMA node0 CPU(s): 0-55,112-167 NUMA node1 CPU(s): 56-111,168-223 Vulnerability Gather data sampling: Not affected Vulnerability Itlb multihit: Not affected Vulnerability L1tf: Not affected Vulnerability Mds: Not affected Vulnerability Meltdown: Not affected Vulnerability Mmio stale data: Not affected Vulnerability Reg file data sampling: Not affected Vulnerability Retbleed: Not affected Vulnerability Spec rstack overflow: Not affected Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization Vulnerability Spectre v2: Mitigation; Enhanced / Automatic IBRS; IBPB conditional; RSB filling; PBRSB-eIBRS SW sequence; BHI BHI_DIS_S Vulnerability Srbds: Not affected Vulnerability Tsx async abort: Not affected

Code Example

vllm serve /models/deepseek-ai/DeepSeek-V4-Flash \
  --served-model-name dpskv4 \
  --trust-remote-code \
  --kv-cache-dtype fp8 \
  --block-size 256 \
  --enable-expert-parallel \
  -cc.pass_config.fuse_allreduce_rms=False \
  --tensor-parallel-size 16 \
  --nnodes 2 \
  --node-rank 0 \
  --master-addr xxx \
  --max-model-len 20480 \
  --gpu-memory-utilization 0.95 \
  --max-num-seqs 256 \
  --max-num-batched-tokens 512 \
  --no-enable-flashinfer-autotune \
  --compilation-config '{"mode": 0, "cudagraph_mode": "FULL_DECODE_ONLY"}' \
  --tokenizer-mode deepseek_v4 \
  --tool-call-parser deepseek_v4 \
  --enable-auto-tool-choice \
  --reasoning-parser deepseek_v4

---

vllm serve /models/deepseek-ai/DeepSeek-V4-Flash \
  --served-model-name dpskv4 \
  --trust-remote-code \
  --kv-cache-dtype fp8 \
  --block-size 256 \
  --enable-expert-parallel \
  -cc.pass_config.fuse_allreduce_rms=False \
  --tensor-parallel-size 16 \
  --nnodes 2 \
  --node-rank 1 \
  --master-addr xxx \
  --headless \
  --max-model-len 20480 \
  --gpu-memory-utilization 0.95 \
  --max-num-seqs 256 \
  --max-num-batched-tokens 512 \
  --no-enable-flashinfer-autotune \
  --compilation-config '{"mode": 0, "cudagraph_mode": "FULL_DECODE_ONLY"}' \
  --tokenizer-mode deepseek_v4 \
  --tool-call-parser deepseek_v4 \
  --enable-auto-tool-choice \
  --reasoning-parser deepseek_v4

---

(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] Traceback (most recent call last):
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/executor/multiproc_executor.py", line 837, in worker_main
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     worker = WorkerProc(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     return func(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]            ^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/executor/multiproc_executor.py", line 619, in __init__
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.worker.load_model()
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/worker/gpu_worker.py", line 345, in load_model
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.model_runner.load_model(load_dummy_weights=load_dummy_weights)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     return func(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]            ^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/worker/gpu_model_runner.py", line 4992, in load_model
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.model = model_loader.load_model(
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]                  ^^^^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     return func(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]            ^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/model_loader/base_loader.py", line 80, in load_model
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     process_weights_after_loading(model, model_config, target_device)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/model_loader/utils.py", line 111, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     quant_method.process_weights_after_loading(module)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/layers/quantization/fp8.py", line 435, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.fp8_linear.process_weights_after_loading(layer)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/kernels/linear/scaled_mm/flashinfer.py", line 175, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.fallback.process_weights_after_loading(layer)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/kernels/linear/scaled_mm/deep_gemm.py", line 96, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     dg_weight, dg_weight_scale = deepgemm_post_process_fp8_weight_block(
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/layers/quantization/utils/fp8_utils.py", line 1036, in deepgemm_post_process_fp8_weight_block
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     r = wq.size(0) // g
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]         ~~~~~~~~~~~^^~~
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ZeroDivisionError: integer division or modulo by zero
RAW_BUFFERClick to expand / collapse

Your current environment

Collecting environment information...

    System Info

============================== OS : Ubuntu 22.04.5 LTS (x86_64) GCC version : (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0 Clang version : Could not collect CMake version : Could not collect Libc version : glibc-2.35

============================== PyTorch Info

PyTorch version : 2.11.0+cu130 Is debug build : False CUDA used to build PyTorch : 13.0 ROCM used to build PyTorch : N/A XPU used to build PyTorch : N/A

============================== Python Environment

Python version : 3.12.13 (main, Mar 4 2026, 09:23:07) [GCC 11.4.0] (64-bit runtime) Python platform : Linux-5.15.0-117-generic-x86_64-with-glibc2.35

============================== CUDA / GPU Info

Is CUDA available : True CUDA runtime version : 13.0.88 CUDA_MODULE_LOADING set to : GPU models and configuration : GPU 0: NVIDIA H20 GPU 1: NVIDIA H20 GPU 2: NVIDIA H20 GPU 3: NVIDIA H20

Nvidia driver version : 570.172.08 cuDNN version : Could not collect HIP runtime version : N/A MIOpen runtime version : N/A Is XNNPACK available : True

============================== CPU Info

Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Address sizes: 46 bits physical, 57 bits virtual Byte Order: Little Endian CPU(s): 224 On-line CPU(s) list: 0-223 Vendor ID: GenuineIntel Model name: Intel(R) Xeon(R) Platinum 8480+ CPU family: 6 Model: 143 Thread(s) per core: 2 Core(s) per socket: 56 Socket(s): 2 Stepping: 8 CPU max MHz: 3800.0000 CPU min MHz: 800.0000 BogoMIPS: 4000.00 Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cat_l2 cdp_l3 invpcid_single intel_ppin cdp_l2 ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb intel_pt avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local split_lock_detect avx_vnni avx512_bf16 wbnoinvd dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req avx512vbmi umip pku ospke waitpkg avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg tme avx512_vpopcntdq la57 rdpid bus_lock_detect cldemote movdiri movdir64b enqcmd fsrm md_clear serialize tsxldtrk pconfig arch_lbr amx_bf16 avx512_fp16 amx_tile amx_int8 flush_l1d arch_capabilities Virtualization: VT-x L1d cache: 5.3 MiB (112 instances) L1i cache: 3.5 MiB (112 instances) L2 cache: 224 MiB (112 instances) L3 cache: 210 MiB (2 instances) NUMA node(s): 2 NUMA node0 CPU(s): 0-55,112-167 NUMA node1 CPU(s): 56-111,168-223 Vulnerability Gather data sampling: Not affected Vulnerability Itlb multihit: Not affected Vulnerability L1tf: Not affected Vulnerability Mds: Not affected Vulnerability Meltdown: Not affected Vulnerability Mmio stale data: Not affected Vulnerability Reg file data sampling: Not affected Vulnerability Retbleed: Not affected Vulnerability Spec rstack overflow: Not affected Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization Vulnerability Spectre v2: Mitigation; Enhanced / Automatic IBRS; IBPB conditional; RSB filling; PBRSB-eIBRS SW sequence; BHI BHI_DIS_S Vulnerability Srbds: Not affected Vulnerability Tsx async abort: Not affected

============================== Versions of relevant libraries

[pip3] flashinfer-python==0.6.11.post2 [pip3] numpy==2.2.6 [pip3] nvidia-cublas==13.1.0.3 [pip3] nvidia-cuda-cupti==13.0.85 [pip3] nvidia-cuda-nvrtc==13.0.88 [pip3] nvidia-cuda-runtime==13.0.96 [pip3] nvidia-cudnn-cu13==9.19.0.56 [pip3] nvidia-cudnn-frontend==1.18.0 [pip3] nvidia-cufft==12.0.0.61 [pip3] nvidia-cufile==1.15.1.6 [pip3] nvidia-curand==10.4.0.35 [pip3] nvidia-cusolver==12.0.4.66 [pip3] nvidia-cusparse==12.6.3.3 [pip3] nvidia-cusparselt-cu13==0.8.0 [pip3] nvidia-cutlass-dsl==4.5.0 [pip3] nvidia-cutlass-dsl-libs-base==4.5.0 [pip3] nvidia-cutlass-dsl-libs-cu13==4.5.0 [pip3] nvidia-ml-py==13.595.45 [pip3] nvidia-nccl-cu13==2.28.9 [pip3] nvidia-nvjitlink==13.0.88 [pip3] nvidia-nvshmem-cu13==3.4.5 [pip3] nvidia-nvtx==13.0.85 [pip3] pyzmq==27.1.0 [pip3] tokenspeed-triton==3.7.10.post20260505 [pip3] torch==2.11.0+cu130 [pip3] torch_c_dlpack_ext==0.1.5 [pip3] torchaudio==2.11.0+cu130 [pip3] torchvision==0.26.0+cu130 [pip3] transformers==5.8.1 [pip3] triton==3.6.0 [conda] Could not collect

============================== vLLM Info

ROCM Version : Could not collect vLLM Version : 0.21.1rc1.dev46+gb50646e5e (git sha: b50646e5e) vLLM Build Flags: CUDA Archs: 7.5 8.0 8.6 8.9 9.0 10.0 12.0+PTX; ROCm: Disabled; XPU: Disabled GPU Topology: GPU0 GPU1 GPU2 GPU3 NIC0 NIC1 NIC2 NIC3 NIC4 NIC5 NIC6 CPU Affinity NUMA Affinity GPU NUMA ID GPU0 X NV18 NV18 NV18 NODE NODE SYS SYS SYS SYS NODE 0-55,112-167 0 N/A GPU1 NV18 X NV18 NV18 SYS SYS PIX NODE NODE NODE SYS 56-111,168-223 1 N/A GPU2 NV18 NV18 X NV18 SYS SYS NODE NODE NODE NODE SYS 56-111,168-223 1 N/A GPU3 NV18 NV18 NV18 X SYS SYS NODE NODE NODE PIX SYS 56-111,168-223 1 N/A NIC0 NODE SYS SYS SYS X NODE SYS SYS SYS SYS NODE NIC1 NODE SYS SYS SYS NODE X SYS SYS SYS SYS NODE NIC2 SYS PIX NODE NODE SYS SYS X NODE NODE NODE SYS NIC3 SYS NODE NODE NODE SYS SYS NODE X PIX NODE SYS NIC4 SYS NODE NODE NODE SYS SYS NODE PIX X NODE SYS NIC5 SYS NODE NODE PIX SYS SYS NODE NODE NODE X SYS NIC6 NODE SYS SYS SYS NODE NODE SYS SYS SYS SYS X

Legend:

X = Self SYS = Connection traversing PCIe as well as the SMP interconnect between NUMA nodes (e.g., QPI/UPI) NODE = Connection traversing PCIe as well as the interconnect between PCIe Host Bridges within a NUMA node PHB = Connection traversing PCIe as well as a PCIe Host Bridge (typically the CPU) PXB = Connection traversing multiple PCIe bridges (without traversing the PCIe Host Bridge) PIX = Connection traversing at most a single PCIe bridge NV# = Connection traversing a bonded set of # NVLinks

NIC Legend:

NIC0: mlx5_0 NIC1: mlx5_3 NIC2: mlx5_4 NIC3: mlx5_5 NIC4: mlx5_6 NIC5: mlx5_7 NIC6: mlx5_bond_0

============================== Environment Variables

NVIDIA_VISIBLE_DEVICES=GPU-0b3dc09e-06f2-e4a5-62df-fa0658ede135,GPU-7cb78b8b-a7d9-28ea-d7dd-e520f4839d55,GPU-c2a4fcb4-06fe-9a17-ec29-ee99a44515c9,GPU-fab144ca-602b-c2bd-b836-af31d869d8af NVIDIA_REQUIRE_CUDA=cuda>=13.0 brand=unknown,driver>=535,driver<536 brand=grid,driver>=535,driver<536 brand=tesla,driver>=535,driver<536 brand=nvidia,driver>=535,driver<536 brand=quadro,driver>=535,driver<536 brand=quadrortx,driver>=535,driver<536 brand=nvidiartx,driver>=535,driver<536 brand=vapps,driver>=535,driver<536 brand=vpc,driver>=535,driver<536 brand=vcs,driver>=535,driver<536 brand=vws,driver>=535,driver<536 brand=cloudgaming,driver>=535,driver<536 brand=unknown,driver>=550,driver<551 brand=grid,driver>=550,driver<551 brand=tesla,driver>=550,driver<551 brand=nvidia,driver>=550,driver<551 brand=quadro,driver>=550,driver<551 brand=quadrortx,driver>=550,driver<551 brand=nvidiartx,driver>=550,driver<551 brand=vapps,driver>=550,driver<551 brand=vpc,driver>=550,driver<551 brand=vcs,driver>=550,driver<551 brand=vws,driver>=550,driver<551 brand=cloudgaming,driver>=550,driver<551 brand=unknown,driver>=565,driver<566 brand=grid,driver>=565,driver<566 brand=tesla,driver>=565,driver<566 brand=nvidia,driver>=565,driver<566 brand=quadro,driver>=565,driver<566 brand=quadrortx,driver>=565,driver<566 brand=nvidiartx,driver>=565,driver<566 brand=vapps,driver>=565,driver<566 brand=vpc,driver>=565,driver<566 brand=vcs,driver>=565,driver<566 brand=vws,driver>=565,driver<566 brand=cloudgaming,driver>=565,driver<566 brand=unknown,driver>=570,driver<571 brand=grid,driver>=570,driver<571 brand=tesla,driver>=570,driver<571 brand=nvidia,driver>=570,driver<571 brand=quadro,driver>=570,driver<571 brand=quadrortx,driver>=570,driver<571 brand=nvidiartx,driver>=570,driver<571 brand=vapps,driver>=570,driver<571 brand=vpc,driver>=570,driver<571 brand=vcs,driver>=570,driver<571 brand=vws,driver>=570,driver<571 brand=cloudgaming,driver>=570,driver<571 brand=unknown,driver>=575,driver<576 brand=grid,driver>=575,driver<576 brand=tesla,driver>=575,driver<576 brand=nvidia,driver>=575,driver<576 brand=quadro,driver>=575,driver<576 brand=quadrortx,driver>=575,driver<576 brand=nvidiartx,driver>=575,driver<576 brand=vapps,driver>=575,driver<576 brand=vpc,driver>=575,driver<576 brand=vcs,driver>=575,driver<576 brand=vws,driver>=575,driver<576 brand=cloudgaming,driver>=575,driver<576 TORCH_CUDA_ARCH_LIST=7.5 8.0 8.6 8.9 9.0 10.0 12.0+PTX CUDA_DEVICE_SM_LIMIT=100 NVIDIA_DRIVER_CAPABILITIES=compute,utility VLLM_USAGE_SOURCE=production-docker-image CUDA_VERSION=13.0.2 VLLM_ENABLE_CUDA_COMPATIBILITY=0 CUDA_DEVICE_MEMORY_LIMIT_0=97871m CUDA_DEVICE_MEMORY_LIMIT_1=97871m CUDA_DEVICE_MEMORY_LIMIT_2=97871m CUDA_DEVICE_MEMORY_LIMIT_3=97871m CUDA_DEVICE_MEMORY_SHARED_CACHE=/usr/local/vgpu/bc056577-8ab3-481b-8780-2526571c3936.cache LD_LIBRARY_PATH=/usr/local/nvidia/lib64:/usr/local/cuda/lib64:/usr/local/nvidia/lib:/usr/local/nvidia/lib64:/usr/local/cuda/lib64 PYTORCH_NVML_BASED_CUDA_CHECK=1 TORCHINDUCTOR_COMPILE_THREADS=1 TORCHINDUCTOR_CACHE_DIR=/tmp/torchinductor_root

🐛 Describe the bug

  • GPU: H20 (16 cards across 2 nodes, 8 per node)
  • Tensor Parallelism: TP=16
  • vLLM Version: Latest main
  • Quantization: FP8 (with DeepGEMM kernel)
  • Model: DeepSeek-V4-Flash
vllm serve /models/deepseek-ai/DeepSeek-V4-Flash \
  --served-model-name dpskv4 \
  --trust-remote-code \
  --kv-cache-dtype fp8 \
  --block-size 256 \
  --enable-expert-parallel \
  -cc.pass_config.fuse_allreduce_rms=False \
  --tensor-parallel-size 16 \
  --nnodes 2 \
  --node-rank 0 \
  --master-addr xxx \
  --max-model-len 20480 \
  --gpu-memory-utilization 0.95 \
  --max-num-seqs 256 \
  --max-num-batched-tokens 512 \
  --no-enable-flashinfer-autotune \
  --compilation-config '{"mode": 0, "cudagraph_mode": "FULL_DECODE_ONLY"}' \
  --tokenizer-mode deepseek_v4 \
  --tool-call-parser deepseek_v4 \
  --enable-auto-tool-choice \
  --reasoning-parser deepseek_v4
vllm serve /models/deepseek-ai/DeepSeek-V4-Flash \
  --served-model-name dpskv4 \
  --trust-remote-code \
  --kv-cache-dtype fp8 \
  --block-size 256 \
  --enable-expert-parallel \
  -cc.pass_config.fuse_allreduce_rms=False \
  --tensor-parallel-size 16 \
  --nnodes 2 \
  --node-rank 1 \
  --master-addr xxx \
  --headless \
  --max-model-len 20480 \
  --gpu-memory-utilization 0.95 \
  --max-num-seqs 256 \
  --max-num-batched-tokens 512 \
  --no-enable-flashinfer-autotune \
  --compilation-config '{"mode": 0, "cudagraph_mode": "FULL_DECODE_ONLY"}' \
  --tokenizer-mode deepseek_v4 \
  --tool-call-parser deepseek_v4 \
  --enable-auto-tool-choice \
  --reasoning-parser deepseek_v4

Problem Description When launching vLLM with tensor parallelism across 16 GPUs (TP=16) on dual-node H20, the worker processes crash during model loading with a ZeroDivisionError. The error occurs in deepgemm_post_process_fp8_weight_block when computing r = wq.size(0) // g, where g (batch size for grouped BMM) evaluates to 0.

Error Log

(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] Traceback (most recent call last):
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/executor/multiproc_executor.py", line 837, in worker_main
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     worker = WorkerProc(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     return func(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]            ^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/executor/multiproc_executor.py", line 619, in __init__
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.worker.load_model()
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/worker/gpu_worker.py", line 345, in load_model
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.model_runner.load_model(load_dummy_weights=load_dummy_weights)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     return func(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]            ^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/v1/worker/gpu_model_runner.py", line 4992, in load_model
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.model = model_loader.load_model(
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]                  ^^^^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/tracing/otel.py", line 178, in sync_wrapper
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     return func(*args, **kwargs)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]            ^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/model_loader/base_loader.py", line 80, in load_model
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     process_weights_after_loading(model, model_config, target_device)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/model_loader/utils.py", line 111, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     quant_method.process_weights_after_loading(module)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/layers/quantization/fp8.py", line 435, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.fp8_linear.process_weights_after_loading(layer)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/kernels/linear/scaled_mm/flashinfer.py", line 175, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     self.fallback.process_weights_after_loading(layer)
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/kernels/linear/scaled_mm/deep_gemm.py", line 96, in process_weights_after_loading
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     dg_weight, dg_weight_scale = deepgemm_post_process_fp8_weight_block(
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]   File "/usr/local/lib/python3.12/dist-packages/vllm/model_executor/layers/quantization/utils/fp8_utils.py", line 1036, in deepgemm_post_process_fp8_weight_block
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]     r = wq.size(0) // g
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870]         ~~~~~~~~~~~^^~~
(Worker_TP4_EP4 pid=612) ERROR 05-19 11:59:55 [multiproc_executor.py:870] ZeroDivisionError: integer division or modulo by zero

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vllm - 💡(How to fix) Fix [Bug]: ZeroDivisionError in deepgemm_post_process_fp8_weight_block when loading FP8 model with TP=16 on dual-node H20