deepspeedai / deepspeedai/DeepSpeed

[BUG] In zero3 mode, how to set nn.Linear weight (some parameters can be updated, but some cannot).

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Description

Describe the bug
For zero3, all of the parameters are partitioned, so the weight shape of nn.Linear is 0, and grad cannot be set for some dimensions of weight.

To Reproduce

from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

model = AutoModelForCausalLM.from_pretrained("Qwen/Qwen-VL")
model.lm_head.weight.data[-1, :].requires_grad_(True)

RUN torchrun --nproc_per_node 8 code.py --deepspeed_config ds_config_zero3.json

Expected behavior
Code runs successfully in the mode of deepspeed zero3.

### Tasks
### Tasks

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the Qwen/Qwen-VL reproduction in code.py and ds_config_zero3.json, running it with torchrun on eight processes. Trace how zero3 partitions lm_head.weight and handles the attempted requires_grad_ update on a selected row. Done means the reproduction runs successfully under DeepSpeed zero3 with the intended parameter update behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
python, pytorch
Domain
distributed-systems, machine-learning
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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