Re: [PATCH v2 3/6] SUNRPC: Handle NULL entries in svc_rqst_release_pages

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2026-02-26 at 09:47 -0500, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> svc_rqst_release_pages() releases response pages between rq_respages
> and rq_next_page. It currently passes the entire range to
> release_pages(), which does not expect NULL entries.
> 
> A subsequent patch preserves the rq_next_page pointer in
> svc_rdma_save_io_pages() so that it accurately records how many
> response pages were consumed. After that change, the range
> 
>   [rq_respages, rq_next_page)
> 
> can contain NULL entries where pages have already been transferred
> to a send context.
> 
> Iterate through the range entry by entry, skipping NULLs, to handle
> this case correctly.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  net/sunrpc/svc.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
> index 9abef638b1e0..0ce16e9abdf6 100644
> --- a/net/sunrpc/svc.c
> +++ b/net/sunrpc/svc.c
> @@ -990,18 +990,24 @@ EXPORT_SYMBOL_GPL(svc_rqst_replace_page);
>   * svc_rqst_release_pages - Release Reply buffer pages
>   * @rqstp: RPC transaction context
>   *
> - * Release response pages that might still be in flight after
> - * svc_send, and any spliced filesystem-owned pages.
> + * Release response pages in the range [rq_respages, rq_next_page).
> + * NULL entries in this range are skipped, allowing transports to
> + * transfer pages to a send context before this function runs.
>   */
>  void svc_rqst_release_pages(struct svc_rqst *rqstp)
>  {
> -	int i, count = rqstp->rq_next_page - rqstp->rq_respages;
> +	struct page **pp;
>  
> -	if (count) {
> -		release_pages(rqstp->rq_respages, count);
> -		for (i = 0; i < count; i++)
> -			rqstp->rq_respages[i] = NULL;
> +	for (pp = rqstp->rq_respages; pp < rqstp->rq_next_page; pp++) {
> +		if (*pp) {
> +			if (!folio_batch_add(&rqstp->rq_fbatch,
> +					     page_folio(*pp)))
> +				__folio_batch_release(&rqstp->rq_fbatch);
> +			*pp = NULL;
> +		}
>  	}
> +	if (rqstp->rq_fbatch.nr)
> +		__folio_batch_release(&rqstp->rq_fbatch);
>  }
>  
>  /**

Reviewed-by: Jeff Layton <jlayton@kernel.org>