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Thu, 5 Nov 2026 09:50:11 +0000 (GMT) Received: from [9.123.14.188] (unknown [9.123.14.188]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Thu, 5 Nov 2026 09:50:11 +0000 (GMT) Message-ID: <78beaf8e-6357-4856-8464-717bb47d74a4@linux.ibm.com> Date: Thu, 5 Nov 2026 15:20:09 +0530 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] net/smc: deregister the MR when SG mapping fails To: Wentao Liang , "D. Wythe" , Dust Li , Sidraya Jayagond , Tony Lu , Wen Gu , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman References: <20261104022812.1484233-1-vulab@iscas.ac.cn> Content-Language: en-US Cc: linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org From: Mahanta Jambigi In-Reply-To: <20261104022812.1484233-1-vulab@iscas.ac.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=Zsp4uN7G c=1 sm=1 tr=0 ts=6aec515a cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Ruwe0kKRUAsyMHfTDyMA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: llxEXSJ92mwsL0YGbs24MbVE2Tb2cnFU X-Proofpoint-GUID: QBXzzbW26_VqFZhZxFxkn4K-9NLxyoG8 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTA1MDAzOCBTYWx0ZWRfX/F+/mquu0ObP pKNJT3e5LACx4XtI7jMvXajAhTEx4ySfAo+jtLcZr5iwP8TRL1DJhp0fztiOog0S1SxsgnH69kC X2d0L9eBscWYfB2bsjaarZEB31NZCQ3NqBdlOLeVEp7GTlvbdzQrVKP4IcvrFiLYRLsQi6AAJ21 WfzRawXtHxFgJxTuPW7ylY5RS2gwqOKNeOSnMutjpbPFZ63P2Btam/mtHZ3jkKhP1he0/NphzHO xzu/qTsqKi0f+8Afz5i6e1/CKQTsnmswUNDUDt73I/12+MEVqjvSDULULPoIbJ+eUO/Vybm4mV1 uvhvajow0fq8zxM2AAW5AW+LrOMXBR3+Y9AwwEaz2yBfx+jYkC4ZbXHzRJ4eHn6u8UD903hsLqW FOY2DpggWBXa+GIpiW4XhR0Mbu1qj6dZnq3AYQxO0pajR0vZGNbXRtX605Mkoh6cDwWKgHAZ0JU trX85tXuS5VxK0N4crw== X-Proofpoint-Spam-Info: AW1haW4tMjYxMTA1MDAzOCBTYWx0ZWRfX7+W4sB5iOJlQ ShhOO2/FPzSAzw4FmKs/kLtWwYZ/LacEHuJNFwhZB3yN+dBZCW8U08YvPpjE045x8GLooD+1sK+ 5+6lS5fecKpJ3Ip/LBJJ/yEj+0Tj7pg= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-05_02,2026-11-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 adultscore=0 priorityscore=1501 bulkscore=0 clxscore=1011 impostorscore=0 spamscore=0 malwarescore=0 suspectscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610300000 definitions=main-2611050038 Going forward Subject should mentioned PATCH net. On 04/11/26 7:58 am, Wentao Liang wrote: > When smc_ib_map_mr_sg() maps fewer entries than the SG table holds, > smc_ib_get_memory_region() returns -EINVAL with the memory region > still allocated and its pointer left in buf_slot->mr[link_idx]. > The caller only undoes the DMA mapping and frees the SG table, and > because buf_desc->is_map_ib[] is set only after this function > succeeds, smcr_buf_unmap_link() later skips the buffer. Both the > MR and the pd->usecnt reference taken by ib_alloc_mr() are lost. > > The stale pointer is also harmful: a retry takes the "already done" > shortcut and treats a memory region that was never mapped as valid. > > Deregister the memory region and clear the slot before returning. > > Fixes: 897e1c245773 ("net/smc: use separate memory regions for RMBs") > Cc: stable@vger.kernel.org > Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex This is not required. > Signed-off-by: Wentao Liang Reviewed-by: Mahanta Jambigi > --- > net/smc/smc_ib.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c > index daaa8a72da90..fa21d269196e 100644 > --- a/net/smc/smc_ib.c > +++ b/net/smc/smc_ib.c > @@ -735,8 +735,11 @@ int smc_ib_get_memory_region(struct ib_pd *pd, int access_flags, > } > > if (smc_ib_map_mr_sg(buf_slot, link_idx) != > - buf_slot->sgt[link_idx].orig_nents) > + buf_slot->sgt[link_idx].orig_nents) { > + smc_ib_put_memory_region(buf_slot->mr[link_idx]); > + buf_slot->mr[link_idx] = NULL; > return -EINVAL; > + } > > return 0; > }