From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7AAAC433EF for ; Mon, 18 Apr 2022 12:59:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240806AbiDRNBo (ORCPT ); Mon, 18 Apr 2022 09:01:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239652AbiDRMuZ (ORCPT ); Mon, 18 Apr 2022 08:50:25 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81B772CCB7; Mon, 18 Apr 2022 05:34:15 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1EEEBB80EDC; Mon, 18 Apr 2022 12:34:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F8CDC385A1; Mon, 18 Apr 2022 12:34:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650285252; bh=6/aVB/eAzoB2Sz2DHvIrvyJiFvWJ+nwIA8Dtc/D44Yc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WuA9qrZpE2E7CxgB0aHVPYd1EeGSXqN6lCCO1BApf1brKAuQdjMam+M4Sa06s9pmy 9nbllwG5BDzHc/KPV8Z6t06TPotQqZmacoJmW5VHr3RUhVLGBRZZUKHM6TotJP2yBF 3lpjrS8YS3y26GoXmlww+aNS26HukUBtXPRVi8Gc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Trond Myklebust , Chuck Lever Subject: [PATCH 5.15 150/189] SUNRPC: Fix NFSDs request deferral on RDMA transports Date: Mon, 18 Apr 2022 14:12:50 +0200 Message-Id: <20220418121206.130360041@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121200.312988959@linuxfoundation.org> References: <20220418121200.312988959@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chuck Lever commit 773f91b2cf3f52df0d7508fdbf60f37567cdaee4 upstream. Trond Myklebust reports an NFSD crash in svc_rdma_sendto(). Further investigation shows that the crash occurred while NFSD was handling a deferred request. This patch addresses two inter-related issues that prevent request deferral from working correctly for RPC/RDMA requests: 1. Prevent the crash by ensuring that the original svc_rqst::rq_xprt_ctxt value is available when the request is revisited. Otherwise svc_rdma_sendto() does not have a Receive context available with which to construct its reply. 2. Possibly since before commit 71641d99ce03 ("svcrdma: Properly compute .len and .buflen for received RPC Calls"), svc_rdma_recvfrom() did not include the transport header in the returned xdr_buf. There should have been no need for svc_defer() and friends to save and restore that header, as of that commit. This issue is addressed in a backport-friendly way by simply having svc_rdma_recvfrom() set rq_xprt_hlen to zero unconditionally, just as svc_tcp_recvfrom() does. This enables svc_deferred_recv() to correctly reconstruct an RPC message received via RPC/RDMA. Reported-by: Trond Myklebust Link: https://lore.kernel.org/linux-nfs/82662b7190f26fb304eb0ab1bb04279072439d4e.camel@hammerspace.com/ Signed-off-by: Chuck Lever Cc: Signed-off-by: Greg Kroah-Hartman --- include/linux/sunrpc/svc.h | 1 + net/sunrpc/svc_xprt.c | 3 +++ net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 2 +- 3 files changed, 5 insertions(+), 1 deletion(-) --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -384,6 +384,7 @@ struct svc_deferred_req { size_t addrlen; struct sockaddr_storage daddr; /* where reply must come from */ size_t daddrlen; + void *xprt_ctxt; struct cache_deferred_req handle; size_t xprt_hlen; int argslen; --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1213,6 +1213,8 @@ static struct cache_deferred_req *svc_de dr->daddr = rqstp->rq_daddr; dr->argslen = rqstp->rq_arg.len >> 2; dr->xprt_hlen = rqstp->rq_xprt_hlen; + dr->xprt_ctxt = rqstp->rq_xprt_ctxt; + rqstp->rq_xprt_ctxt = NULL; /* back up head to the start of the buffer and copy */ skip = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len; @@ -1251,6 +1253,7 @@ static noinline int svc_deferred_recv(st rqstp->rq_xprt_hlen = dr->xprt_hlen; rqstp->rq_daddr = dr->daddr; rqstp->rq_respages = rqstp->rq_pages; + rqstp->rq_xprt_ctxt = dr->xprt_ctxt; svc_xprt_received(rqstp->rq_xprt); return (dr->argslen<<2) - dr->xprt_hlen; } --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -826,7 +826,7 @@ int svc_rdma_recvfrom(struct svc_rqst *r goto out_err; if (ret == 0) goto out_drop; - rqstp->rq_xprt_hlen = ret; + rqstp->rq_xprt_hlen = 0; if (svc_rdma_is_reverse_direction_reply(xprt, ctxt)) goto out_backchannel;