Resolves https://github.com/pytorch/pytorch/issues/146767.
May also resolve https://github.com/pytorch/pytorch/issues/147584.
### Summary
This PR removes the RNG tracker init from the `distribute_tensor` call for the following reasons:
1. if the user does not use random ops on DTensor, there's no need to init DTensor RNG which currently requires CUDA device to be present.
2. this complies with the 0-communication semantic of `src_data_rank=None` shard distribution.
Besides, `OffsetBasedRNGTracker` only accepts `DeviceMesh` argument to its constructor method.
### Consequence
DTensor RNG initialization is delayed till the first DTensor random ops call or `torch.distributed.tensor.random.manual_seed`.
### Test
`pytest test/distributed/tensor/test_random_ops.py`
`pytest test/distributed/tensor/parallel/test_tp_random_state.py`
`pytest test/distributed/tensor/parallel/test_tp_style.py`
Differential Revision: [D70201856](https://our.internmc.facebook.com/intern/diff/D70201856)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/147025
Approved by: https://github.com/kwen2501
**Summary**
Added tests for model meta init on 1-d mesh (TP) and 2-d mesh (FSDP+TP). This exploits the issue where DTensor RNG failed to initialize weights differently across FSDP ranks.
**Test**
`pytest test/distributed/_tensor/test_random_ops.py -s -k meta_init`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/141731
Approved by: https://github.com/wconstab
reland of https://github.com/pytorch/pytorch/pull/133113
I have to create a new PR because the previous reverted PR could not either be rebased, or imported successfully :(
----
Moving DTensor to be in the public namespace, to formally add the documentation page that includes all the public APIs. This includes:
* many path renames and path import fixes
* a dedicated doc page without too much content yet (adding in the next PRs)
* To preserve the BC for users still using the torch.distributed._tensor, I added a shim script to redirect old path calls to the new module
The BC preserving is evidented by the fact that all DTensor tests are still working without changing the public imports. So it's safe to land the changes
Pull Request resolved: https://github.com/pytorch/pytorch/pull/134203
Approved by: https://github.com/tianyu-l
Moving DTensor to be in the public namespace, to formally add the
documentation page that includes all the public APIs. This includes:
* many path renames and path import fixes
* a dedicated doc page without too much content yet (adding in the next
PRs)
* To preserve the BC for users still using the `torch.distributed._tensor`,
I added a shim script to redirect old path calls to the new module
The BC preserving is evidented by the fact that all DTensor tests are still
working without changing the public imports. So it's safe to land the
changes
Pull Request resolved: https://github.com/pytorch/pytorch/pull/133113
Approved by: https://github.com/XilunWu
ghstack dependencies: #133305, #133306
