pytorch

78175cee - [FSDP][Docs] Re-add why reg. post-bwd hook on 1st forward (#95326)

[FSDP][Docs] Re-add why reg. post-bwd hook on 1st forward (#95326) This PR adds back some explanation for why we have the heuristic to only register the post-backward hook on the first forward in the case of multiple forwards. Pull Request resolved: https://github.com/pytorch/pytorch/pull/95326 Approved by: https://github.com/fegin