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Tue, 22 Sep 2026 15:33:40 +0000 (GMT) Received: from [9.61.143.235] (unknown [9.61.143.235]) by smtpav06.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 22 Sep 2026 15:33:39 +0000 (GMT) Message-ID: Date: Tue, 22 Sep 2026 21:03:38 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] nvme: keep transport module referenced while head node is open From: Nilay Shroff To: Christoph Hellwig , Keith Busch Cc: linux-nvme@lists.infradead.org, sagi@grimberg.me, Jens Axboe , john.g.garry@oracle.com, wenxiong@linux.ibm.com, gjoyce@linux.ibm.com References: <20260831152006.819471-1-nilay@linux.ibm.com> <20260831152006.819471-2-nilay@linux.ibm.com> <20260902133104.GA20945@lst.de> <20260902141347.GA24385@lst.de> <61165430-a724-40d3-a00d-2cbe1ea656b0@linux.ibm.com> <57629796-d346-4cc4-8c9c-b153a60e1709@linux.ibm.com> Content-Language: en-US In-Reply-To: <57629796-d346-4cc4-8c9c-b153a60e1709@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: kFBjXS4CSfRMpNEojaEDg3_ROwQ4t63Q X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIyMDIyMCBTYWx0ZWRfX/y7/jmwuKZOR dx4wYc7ncpi/NrnYRa55jdppXUHEYqB9LWy1HtFtWFglAfmxvEF+1ao5rmCwORAN04y4WYGfZJ0 3/McXoQcQf41xwyvU/GwjbGw77qyUpwf/2YBfrWjQrwi2Y16zyltwi81D4d89NWA/duVT1bM8R5 6wJv7iG9UynAVaNGVYUmLX6PTg29K/VvylOiGnTGwDVtRzYgdQKH2MdfgJfOzhUlf9I794Dfuqw t2Sa/bTlr73Yh86Eo2uEqerjmKM4EqVSnIIfjQbtQLr5Cfgi3+UeSpImHR872uhVO1/cSmbnEH5 YC6d8r7Q/JINrgCsEOPA/lvuDQIDXuSSIXR6mBYvc57HCXyjBBZOM+He7uU7FyuPOjHWZeQn7eJ UApE2jmrFIYRHAehFlCQO0Um3JVA/jPvVskLaQhWz/jmXcAffrXJ7AGKW2t0vEduFU619+AKwGr VNFk9joZaqHfT2kzkQA== X-Authority-Analysis: v=2.4 cv=O/KsLx9W c=1 sm=1 tr=0 ts=6ab29fd9 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=EYdalptScvJjkWXT3cgA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIyMDIyMCBTYWx0ZWRfX5WA2n7ZmB6zs VRhjTZ97Myh8OxU1FEfN7Ka7o+NPSQXhj+nrtS597y/XhBl9SxkF1jFW2gF8MjYtMXEep/GB+lV SyMSISRSR4GLPQ14M4xc2HR9rY0yzlk= X-Proofpoint-GUID: kFBjXS4CSfRMpNEojaEDg3_ROwQ4t63Q 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=2026-09-22_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 malwarescore=0 phishscore=0 impostorscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609220220 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260922_083401_597895_1FCCF2C6 X-CRM114-Status: GOOD ( 20.55 ) 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 Hi Christoph, Keith A gent ping on this one... Do you have any further comment/feedback on this one? Thanks, --Nilay > On 9/2/26 7:57 PM, Nilay Shroff wrote: >> On 9/2/26 7:43 PM, Christoph Hellwig wrote: >>> On Wed, Sep 02, 2026 at 07:39:32PM +0530, Nilay Shroff wrote: >>>> So the practical problem is that an open multipath head can continue to >>>> be used after its underlying transport module has been unloaded. The >>>> proposed change keeps the transport module referenced while the head >>>> node is open, preventing the module from being unloaded in this >>>> scenario. >>> >>> But why do you unload it in the first place? >>> >> Well, in my view, unloading a module while it is not in use should be a legitimate operation. >> >> In the example shown earlier, the NVMe transport module is still being >> used by the open multipath head. Shouldn't we explicitly reflect that by >> incrementing its module refcount? We don't explicitly unload the module >> as part of normal NVMe operation, but in theory I think the transport module >> should remain referenced for as long as it is being used. That would also >> prohibit user from unloading module by mistake. >> >> Thanks, >> --Nilay >