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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 46BD9C88E66 for ; Sun, 13 Sep 2026 14:04:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:References:Cc:To:From:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WkgtGNLVj5lEWP3U7RT04RqO7sIFfDRKjhKOIiBSzdw=; b=X2kFjrQ7Ze2G8EvYmBRdBTj9hm 8j+P1ja4JxhIlZAEnluQq6sndrMibfbDwmuUn0prDsoYLmzWD1jnct44/SYdNGNarVkuYEeRuMrbg qG3ve4fdcrSrKAoZxThQEiyRjmL0vg8c7dMghqN/YHblRqNbhy7HdCPf0UnhGsuQa0WmOLX4Wysmc Y5lxbwk6Lo7ge2B72LruV48HAFt5RQwnKJrO/82nnFbaiA+nbEQuoOtPHyqs+jpZn7KOCwqOYhecV IuU6WDgXk58ci7KKLoFSGxB2dbAVaGUsywEvNBuToBNqKvNwI6iAahoBjwjNA03+PBL4IRYFIyErB dfreFBuw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x5koX-00000001hea-0eyz; Sun, 13 Sep 2026 14:04:13 +0000 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x5koU-00000001heE-2QGn for linux-nvme@lists.infradead.org; Sun, 13 Sep 2026 14:04:11 +0000 Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 68DE1SGx1656118; Sun, 13 Sep 2026 14:03:57 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=WkgtGN LVj5lEWP3U7RT04RqO7sIFfDRKjhKOIiBSzdw=; b=bl2aY2/4jUe0esdIcM12t3 //bJjS4BzZn8H/fq/qDApfdZLpJPve2XAuMawK8vagZ+sIOItfKMR7X+Z0NrGeyH uFBKnDEUvVLic1LCA/2480/wFLytF29IQAWE1jiTPlUmEB2kW9z4zA3AnT4SkMzn c7siBPKkrz8UvgSnFfnZ5EKiyFt+aQ29p9kvyLiaaD6zpb3stWn1gYGq/jaDIiOw WaTP0IFQvBh1ZSAa+wxZ+CXuwgmGsohFHa6ELqv6AnqtN3FuyFWRY7lpmOoUctfd qXEGqZz3grlp2DmHxeQHrHT3UzKHuG4xKzaFwLUhclAwp0acHNDfjkCQiCRatrdw == Received: from ppma11.dal12v.mail.ibm.com (db.9e.1632.ip4.static.sl-reverse.com [50.22.158.219]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4gmxdpvrvb-1 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Sun, 13 Sep 2026 14:03:57 +0000 (GMT) Received: from pps.filterd (ppma11.dal12v.mail.ibm.com [127.0.0.1]) by ppma11.dal12v.mail.ibm.com (8.18.1.11/8.18.1.11) with ESMTP id 68DAZ4SB541223; Sun, 13 Sep 2026 14:03:56 GMT Received: from smtprelay05.dal12v.mail.ibm.com ([172.16.1.7]) by ppma11.dal12v.mail.ibm.com (PPS) with ESMTPS id 4gnkry1d8t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 13 Sep 2026 14:03:56 +0000 (GMT) Received: from smtpav06.dal12v.mail.ibm.com (smtpav06.dal12v.mail.ibm.com [10.241.53.105]) by smtprelay05.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 68DE3txW3146274 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 13 Sep 2026 14:03:55 GMT Received: from smtpav06.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5921458055; Sun, 13 Sep 2026 14:03:55 +0000 (GMT) Received: from smtpav06.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7C41D5805D; Sun, 13 Sep 2026 14:03:52 +0000 (GMT) Received: from [9.61.162.129] (unknown [9.61.162.129]) by smtpav06.dal12v.mail.ibm.com (Postfix) with ESMTP; Sun, 13 Sep 2026 14:03:52 +0000 (GMT) Message-ID: <57629796-d346-4cc4-8c9c-b153a60e1709@linux.ibm.com> Date: Sun, 13 Sep 2026 19:33:51 +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 Cc: linux-nvme@lists.infradead.org, kbusch@kernel.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> Content-Language: en-US In-Reply-To: <61165430-a724-40d3-a00d-2cbe1ea656b0@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTEzMDIwMSBTYWx0ZWRfX97x4eMQso7sG JJWfbIsqibxqQ41Z3V+7B1xxIPMZ84WcDV3o0uLy3lgTQBIl/a9zlWbqHJGkurID3RYHCO5BnTX q0PRalEI6vGi/BAEE+af+wRLmGHuYUAb111MD1Te9PS+jZYWQJ1iG1+J4R63FYiBoVWuU+H2Vp6 kJkI8Itpg30WE4rYhdE98nJUsBSXuH8OyyEDKjyS6tV8LnTOg2Bkrq45BM1O0BFHr9GkfJY01qz DK/JV5ze0NdU0pYVZAmfwGFSUS1G57VvRlBmooN9CVLDNvJ6BrrkFqxiegw3wlFTJz/H/IrwJ05 uF+MAIyKmOfZDOfozGSU+vUI62UDZ8fN/WH3bqD7VIVJ9yBTD7r5Jh2FI9v6mbH/6SVpuRnPRgr hrn3kgQYivwPd4J7prizamdLhSeiyHdtvoBiHHSl9gF+/mOJ1jU+W0jBzKB8q1LgG/7IFV1bWTA MdE2z6SFnRsZdKQQRkQ== X-Proofpoint-GUID: pyUXw0zM3MGgjjjZvQGHQzfcZjlBxi31 X-Authority-Analysis: v=2.4 cv=DobDa2/+ c=1 sm=1 tr=0 ts=6aa6ad4d cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=AXAQGVf3kW131NiH-mUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: pyUXw0zM3MGgjjjZvQGHQzfcZjlBxi31 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTEzMDIwMSBTYWx0ZWRfXyY3XBrqSEF5u KF1kNjhWI5EXjn/eyUfLDREJBoyLWXw85zPl9t91dNBjT1sIfHnJyFxAHBkLPQYE00nc53wsoKf 3le5Y/mvrRMLNWMil6Zsl1m2XaWsanM= 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=2026-09-13_05,2026-09-11_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 priorityscore=1501 suspectscore=0 impostorscore=0 spamscore=0 clxscore=1015 adultscore=0 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609130201 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260913_070410_632784_D93CE483 X-CRM114-Status: GOOD ( 20.42 ) 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, A gentle ping on this one... Do you have any further comments on this? 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