Re: [PATCH v3 10/10] liveupdate: Defer file handler module refcounting to active sessions

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 27 Mar 2026 03:33:34 +0000 Pasha Tatashin <pasha.tatashin@soleen.com> wrote:

> Stop pinning modules indefinitely upon file handler registration.
> Instead, dynamically increment the module reference count only when a
> live update session actively uses the file handler (e.g., during
> preservation or deserialization), and release it when the session ends.
> 
> This allows modules providing live update handlers to be gracefully
> unloaded when no live update is in progress.
> 
> ...
>
> @@ -322,6 +323,8 @@ int luo_preserve_file(struct luo_file_set *file_set, u64 token, int fd)
>  	kfree(luo_file);
>  err_flb_unpreserve:
>  	luo_flb_file_unpreserve(fh);
> +err_module_put:
> +	module_put(fh->ops->owner);
>  err_free_files_mem:
>  	luo_free_files_mem(file_set);
>  err_fput:

This didn't anticipate your "liveupdate: prevent double management of
files".  I resolved it thusly:

err_kfree:
	kfree(luo_file);
err_flb_unpreserve:
	luo_flb_file_unpreserve(fh);
err_erase_xa:
	xa_erase(&luo_preserved_files, luo_get_id(fh, file));
err_module_put:
	module_put(fh->ops->owner);
err_free_files_mem:
	luo_free_files_mem(file_set);
err_fput:
	fput(file);

	return err;
}