Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ie0-f181.google.com ([209.85.223.181]:59878 "EHLO mail-ie0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752504AbaAMQH5 convert rfc822-to-8bit (ORCPT ); Mon, 13 Jan 2014 11:07:57 -0500 Received: by mail-ie0-f181.google.com with SMTP id at1so490941iec.26 for ; Mon, 13 Jan 2014 08:07:57 -0800 (PST) Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.1 \(1827\)) Subject: Re: [PATCH] xprtrdma: silence frame size warning From: Trond Myklebust In-Reply-To: <1389627955.20467.9.camel@x41> Date: Mon, 13 Jan 2014 10:59:40 -0500 Cc: Dr Fields James Bruce , "Miller David S." , Linux NFS Mailing List , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: References: <1389627955.20467.9.camel@x41> To: Paul Bolle , Lever Charles Edward Sender: linux-nfs-owner@vger.kernel.org List-ID: On Jan 13, 2014, at 10:45, Paul Bolle wrote: > Building verbs.o on 32 bits x86, with CONFIG_FRAME_WARN set to 1024, its > default value, triggers this GCC warning: > net/sunrpc/xprtrdma/verbs.c: In function ?rpcrdma_register_default_external?: > net/sunrpc/xprtrdma/verbs.c:1774:1: warning: the frame size of 1040 bytes is larger than 1024 bytes [-Wframe-larger-than=] > > Silence this warning by allocating "ipb" dynamically. > > Signed-off-by: Paul Bolle > --- > 0) Compile tested only (on 32 bits x86). I don't have access to > Infiniband hardware. > > 1) Please note that this is not a new warning. The oldest build log I > have still available on this machine is for a v3.8 rc, and it already > showed this warning. > > 2) I do hope my choice for the GFP_KERNEL flag is correct here. > > net/sunrpc/xprtrdma/verbs.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c > index 93726560..939ccc8 100644 > --- a/net/sunrpc/xprtrdma/verbs.c > +++ b/net/sunrpc/xprtrdma/verbs.c > @@ -1736,11 +1736,14 @@ rpcrdma_register_default_external(struct rpcrdma_mr_seg *seg, > int mem_priv = (writing ? IB_ACCESS_REMOTE_WRITE : > IB_ACCESS_REMOTE_READ); > struct rpcrdma_mr_seg *seg1 = seg; > - struct ib_phys_buf ipb[RPCRDMA_MAX_DATA_SEGS]; > + struct ib_phys_buf *ipb; > int len, i, rc = 0; > > if (*nsegs > RPCRDMA_MAX_DATA_SEGS) > *nsegs = RPCRDMA_MAX_DATA_SEGS; > + ipb = kmalloc(sizeof(*ipb) * *nsegs, GFP_KERNEL); > + if (ipb == NULL) > + return -ENOMEM; > for (len = 0, i = 0; i < *nsegs;) { > rpcrdma_map_one(ia, seg, writing); > ipb[i].addr = seg->mr_dma; > @@ -1770,6 +1773,7 @@ rpcrdma_register_default_external(struct rpcrdma_mr_seg *seg, > seg1->mr_len = len; > } > *nsegs = i; > + kfree(ipb); > return rc; > } Hi Paul, Unfortunately, the above could be called from a file write back context, so we cannot use GFP_KERNEL allocations. In fact, I suspect we should only use GFP_ATOMIC, and then have the rpc_task delay and retry if the allocation fails. The problem is that it looks to me as if xprt_rdma_send_request will currently fail, if we return an error from rpcrdma_register_default_external. Chuck, will you be able to look into the above issue as part of your RDMA work? Cheers Trond -- Trond Myklebust Linux NFS client maintainer