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Wed, 2 Sep 2026 00:20:14 +0000 (GMT) Received: from ltc.linux.ibm.com (unknown [9.5.196.140]) by smtpav01.dal12v.mail.ibm.com (Postfix) with ESMTP; Wed, 2 Sep 2026 00:20:14 +0000 (GMT) MIME-Version: 1.0 Date: Tue, 01 Sep 2026 19:20:14 -0500 From: Wen Xiong To: Nilay Shroff Cc: linux-nvme@lists.infradead.org, kbusch@kernel.org, sagi@grimberg.me, hch@lst.de, axboe@fb.com, john.g.garry@oracle.com, gjoyce@linux.ibm.com Subject: Re: [PATCH 1/2] nvme: keep transport module referenced while head node is open In-Reply-To: <20260831152006.819471-2-nilay@linux.ibm.com> References: <20260831152006.819471-1-nilay@linux.ibm.com> <20260831152006.819471-2-nilay@linux.ibm.com> Message-ID: X-Sender: wenxiong@linux.ibm.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=PPc/P/qC c=1 sm=1 tr=0 ts=6a976bc1 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=3rXfYopxgoUhIfHtWu0A:9 a=CjuIK1q_8ugA:10 a=zY0JdQc1-4EAyPf5TuXT:22 X-Proofpoint-GUID: 5QOXPv254FItFR7PI5_AlPNa8qbbg482 X-Proofpoint-ORIG-GUID: 5QOXPv254FItFR7PI5_AlPNa8qbbg482 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTAxMDIxMSBTYWx0ZWRfXxb+6anIKvupR 3CC2/ALCsnPtsWhchs3/2Wa94bGyZzWUP5wMEm82w0pF6GQWWpZFRapaJHEIca+RV+nmlnSraEh yD7bW1EkPYUNe1RQoEVo0Mh5ovjWzKU= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTAxMDIxMSBTYWx0ZWRfXztxVWBi67sy/ h53D+pl6YoodwZ7ItQ2fC8dMm7zroIsmgY5UQRdnCjKqqPuzO37NL9WLW457owhmwpXDGhiCr/Q q4vlv1UGny1M+TtjjpDoLJLntbNL8IGt/3dz/tkfdVq7asSePV70jUHtJUpoi5WOSQyVPl4W4AG 2N0BUzuXZGRyc6NbyZAf9af6hVPYxQfm8sRhf87HcVsZ6rgaxF2wxJLcrQfUv81XjUQ1w+MOjpA Fa4sWDVaeghlzen/8WxUQ4rspbPjf/jkI5J1oMrsHYKMCQ5UNydEslZU7B5ulHvQdLNGdm6Umb8 SnYzinjzJFGaH7ieB14xmQExcVaVY+tCyq/ynWnH8PcP5jxlMghBMrR84YGgY0Oezprv5OiUGLD XiIKK8MdLXQPJLgOndr6+EwxVvsqyGx1/qkUWCS+fvRmLXO7bWVjY14UkZVBvKNxwMpsCFrtwOm FYS9RBQ1GG7GQNAnN+Q== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-01_06,2026-09-01_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 phishscore=0 adultscore=0 suspectscore=0 bulkscore=0 spamscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609010211 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260901_172031_558079_2EC8D80C X-CRM114-Status: GOOD ( 17.17 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 2026-08-31 10:19, Nilay Shroff wrote: > When a user opens an NVMe multipath head node, we take a reference to > the head node, but this does not prevent the transport module backing > its paths from being unloaded. This can result in the multipath head > remaining open while its underlying transport module is unloaded. > > Fix this by taking a reference to the transport module for each active > path when the multipath head node is opened. Keep track of the number > of active head node openers so that dynamically added paths acquire the > same number of transport module references. > > Similarly, when a path is removed while the head node is open, release > the transport module reference once for each active head node opener. > When the head node is closed, release the transport module reference > held for each remaining active path. > > This ensures that a transport module cannot be unloaded while it is > still referenced by an open multipath head node. > > Signed-off-by: Nilay Shroff Hi Nilay, Thank you for your time and effort in working on this issue. I really appreciate your help! Reviewed-by: Wen Xiong Thanks, Wendy