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Tue, 7 May 2024 05:26:39 GMT Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 664FD58063; Tue, 7 May 2024 05:26:37 +0000 (GMT) Received: from smtpav01.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4D8A25804B; Tue, 7 May 2024 05:26:35 +0000 (GMT) Received: from [9.179.27.31] (unknown [9.179.27.31]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 7 May 2024 05:26:35 +0000 (GMT) Message-ID: <80aba643-60a0-4a1c-b90a-de6e0d8d7bc1@linux.ibm.com> Date: Tue, 7 May 2024 07:26:32 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net/smc: fix netdev refcnt leak in smc_ib_find_route() Content-Language: en-GB To: Wen Gu , jaka@linux.ibm.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: alibuda@linux.alibaba.com, tonylu@linux.alibaba.com, linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240506015439.108739-1-guwen@linux.alibaba.com> From: Wenjia Zhang In-Reply-To: <20240506015439.108739-1-guwen@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: PLRDL5ed79G-Pr6Cevz-_ETAaD0VLTMr X-Proofpoint-ORIG-GUID: 7a5cesJQLPVMTgJrsm4VrV-LJOcEzP0r X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.650,FMLib:17.11.176.26 definitions=2024-05-07_02,2024-05-06_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 suspectscore=0 adultscore=0 mlxlogscore=999 impostorscore=0 lowpriorityscore=0 phishscore=0 spamscore=0 mlxscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2405070038 On 06.05.24 03:54, Wen Gu wrote: > A netdev refcnt leak issue was found when unregistering netdev after > using SMC. It can be reproduced as follows. > > - run tests based on SMC. > - unregister the net device. > > The following error message can be observed. > > 'unregister_netdevice: waiting for ethx to become free. Usage count = x' > > With CONFIG_NET_DEV_REFCNT_TRACKER set, more detailed error message can > be provided by refcount tracker: > > unregister_netdevice: waiting for eth1 to become free. Usage count = 2 > ref_tracker: eth%d@ffff9cabc3bf8548 has 1/1 users at > ___neigh_create+0x8e/0x420 > neigh_event_ns+0x52/0xc0 > arp_process+0x7c0/0x860 > __netif_receive_skb_list_core+0x258/0x2c0 > __netif_receive_skb_list+0xea/0x150 > netif_receive_skb_list_internal+0xf2/0x1b0 > napi_complete_done+0x73/0x1b0 > mlx5e_napi_poll+0x161/0x5e0 [mlx5_core] > __napi_poll+0x2c/0x1c0 > net_rx_action+0x2a7/0x380 > __do_softirq+0xcd/0x2a7 > > It is because in smc_ib_find_route(), neigh_lookup() takes a netdev > refcnt but does not release. So fix it. > > Fixes: e5c4744cfb59 ("net/smc: add SMC-Rv2 connection establishment") > Signed-off-by: Wen Gu > --- > net/smc/smc_ib.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c > index 97704a9e84c7..b431bd8a5172 100644 > --- a/net/smc/smc_ib.c > +++ b/net/smc/smc_ib.c > @@ -210,10 +210,11 @@ int smc_ib_find_route(struct net *net, __be32 saddr, __be32 daddr, > goto out; > if (rt->rt_uses_gateway && rt->rt_gw_family != AF_INET) > goto out; > - neigh = rt->dst.ops->neigh_lookup(&rt->dst, NULL, &fl4.daddr); > + neigh = dst_neigh_lookup(&rt->dst, &fl4.daddr); > if (neigh) { > memcpy(nexthop_mac, neigh->ha, ETH_ALEN); > *uses_gateway = rt->rt_uses_gateway; > + neigh_release(neigh); > return 0; > } > out: Hi Wen, Thanks for fixing that! It looks good to me and works well. Please release rt for that condition in the next version. (Thx, @Ratheesh!) Thanks, Wenjia