From 7ed7504287a627834f2a35ef04e5dfd26d1c8986 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 26 Feb 2026 09:47:38 -0500 Subject: SUNRPC: Track consumed rq_pages entries The rq_pages array holds pages allocated for incoming RPC requests. Two transport receive paths NULL entries in rq_pages to prevent svc_rqst_release_pages() from freeing pages that the transport has taken ownership of: - svc_tcp_save_pages() moves partial request data pages to svsk->sk_pages during multi-fragment TCP reassembly. - svc_rdma_clear_rqst_pages() moves request data pages to head->rc_pages because they are targets of active RDMA Read WRs. A new rq_pages_nfree field in struct svc_rqst records how many entries were NULLed. svc_alloc_arg() uses it to refill only those entries rather than scanning the full rq_pages array. In steady state, the transport NULLs a handful of entries per RPC, so the allocator visits only those entries instead of the full ~259 slots (for 1MB messages). Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include') diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 3b1a98ab5cba..c3399cf64524 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -143,6 +143,15 @@ extern u32 svc_max_payload(const struct svc_rqst *rqstp); * server thread needs to allocate more to replace those used in * sending. * + * rq_pages request page contract: + * + * Transport receive paths that move request data pages out of + * rq_pages -- TCP multi-fragment reassembly (svc_tcp_save_pages) + * and RDMA Read I/O (svc_rdma_clear_rqst_pages) -- NULL those + * entries to prevent svc_rqst_release_pages() from freeing pages + * still in transport use, and set rq_pages_nfree to the count. + * svc_alloc_arg() refills only that many rq_pages entries. + * * xdr_buf holds responses; the structure fits NFS read responses * (header, data pages, optional tail) and enables sharing of * client-side routines. @@ -204,6 +213,7 @@ struct svc_rqst { struct folio *rq_scratch_folio; struct xdr_buf rq_res; unsigned long rq_maxpages; /* entries per page array */ + unsigned long rq_pages_nfree; /* rq_pages entries NULLed by transport */ struct page * *rq_pages; /* Call buffer pages */ struct page * *rq_respages; /* Reply buffer pages */ struct page * *rq_next_page; /* next reply page to use */ -- cgit v1.2.3