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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA750C2D0EC for ; Tue, 7 Apr 2020 19:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7509920730 for ; Tue, 7 Apr 2020 19:30:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="sL1XyPJd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726759AbgDGTai (ORCPT ); Tue, 7 Apr 2020 15:30:38 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:34164 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726339AbgDGTai (ORCPT ); Tue, 7 Apr 2020 15:30:38 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 037JSF8w158130; Tue, 7 Apr 2020 19:30:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=SbQe82vHs13pDd9LLSs8DskFa5zQn9QZR3OLcQuV52k=; b=sL1XyPJd/DIpcenknFdHOXkcd0mayJOs1MBfeyzTgztVOblftK+mLAQb+MIIHC2sbVPf v+0ntXlaZ6ttIgkgfTiPIehjf7UK7886+QFMD11u287icjWVE9S9dmOkBPrRGAamQSU+ 48MpbkgjmZzJR3SF/KoS1yjCmOcrLQnrHSWF8+bf50yG8xJmmUnr5s0IFNr0FUgB5BiN c7qFPRzLrJozIXi75uS1o2qqe1hrm2s7HVQIojpLCZU5YHioLUId3kxQmidJ7W8tj08o 1bFONZ+6yuNdVS7f+0ORUzPKZPK7SjrLO/g2rqlJ58KlHAVCz6S456z4At3mveGdk7Ed 0g== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 308ffdd251-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 07 Apr 2020 19:30:29 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 037JQUZL086081; Tue, 7 Apr 2020 19:30:29 GMT Received: from pps.reinject (localhost [127.0.0.1]) by userp3020.oracle.com with ESMTP id 30839u6hrd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 07 Apr 2020 19:30:29 +0000 Received: from userp3020.oracle.com (userp3020.oracle.com [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 037JUTtO096203; Tue, 7 Apr 2020 19:30:29 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 30839u6hqn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 07 Apr 2020 19:30:28 +0000 Received: from abhmp0013.oracle.com (abhmp0013.oracle.com [141.146.116.19]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 037JUSrM006077; Tue, 7 Apr 2020 19:30:28 GMT Received: from [10.159.145.213] (/10.159.145.213) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 07 Apr 2020 12:30:27 -0700 Subject: Re: [PATCH net 2/2] net/rds: Fix MR reference counting problem To: Ka-Cheong Poon , netdev@vger.kernel.org, sironhide0null@gmail.com Cc: davem@davemloft.net, rds-devel@oss.oracle.com References: <4b96ea99c3f0ccd5cc0683a5c944a1c4da41cc38.1586275373.git.ka-cheong.poon@oracle.com> From: santosh.shilimkar@oracle.com Organization: Oracle Corporation Message-ID: <96f17f7d-365c-32ec-2efe-a6a5d9d306b7@oracle.com> Date: Tue, 7 Apr 2020 12:30:26 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9584 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 priorityscore=1501 impostorscore=0 malwarescore=0 mlxlogscore=999 lowpriorityscore=0 clxscore=1015 phishscore=0 mlxscore=0 bulkscore=0 adultscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004070156 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 4/7/20 9:08 AM, Ka-Cheong Poon wrote: > In rds_free_mr(), it calls rds_destroy_mr(mr) directly. But this > defeats the purpose of reference counting and makes MR free handling > impossible. It means that holding a reference does not guarantee that > it is safe to access some fields. For example, In > rds_cmsg_rdma_dest(), it increases the ref count, unlocks and then > calls mr->r_trans->sync_mr(). But if rds_free_mr() (and > rds_destroy_mr()) is called in between (there is no lock preventing > this to happen), r_trans_private is set to NULL, causing a panic. > Similar issue is in rds_rdma_unuse(). > > Reported-by: zerons > Signed-off-by: Ka-Cheong Poon > --- Thanks for getting this out on the list. Hi zerons, Can you please review it and see it addresses your concern ? Regards, Santosh