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[34.105.23.239]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c70fa8479aasm89953a12.31.2026.02.25.15.15.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 15:15:47 -0800 (PST) Date: Wed, 25 Feb 2026 23:15:43 +0000 From: David Matlack To: Alex Williamson Cc: Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Lukas Wunner , =?utf-8?Q?Micha=C5=82?= Winiarski , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun Subject: Re: [PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator Message-ID: References: <20260129212510.967611-1-dmatlack@google.com> <20260129212510.967611-5-dmatlack@google.com> <20260225143328.35be89f6@shazbot.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260225143328.35be89f6@shazbot.org> X-Rspamd-Queue-Id: 37BEC10000A X-Stat-Signature: 493dowt3yxibztbx1fm5pwfhbbrksr3t X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1772061350-170433 X-HE-Meta: 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 bBWk+6e0 mZWT+37BqsQG+LpCc+xz5ofPdbzas1Hzwkc/6Xqp1hXuiaXAHl1DxXfwKtAEL76jXzFXrSQdQvqStyQDX4/9fuyaWI0W5i3pulJ6v657zeC1tdeu9nB1D/9rbPdQdSgvtROSTdKW2/WgFwIKdfbBWQQwoPEY6ZaY8Yfd9ZWacY3cXm6Mw5h+2gsMITvKLEbJm7L4Bd4pXo6rP4tBzwuIlXLsydavTQ/2KBoj3aqIlEtIZLj4mdB1hMXrWPK3OXCnTbngAReBzd7oUGjT53O0BWrKCTcHzm2DU1+sQChtVWh48Z08RVApd0pHOp0wfuwanr1egrDzc0cNTVKUDz5a2pgztIxYoGXKIfRZF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-02-25 02:33 PM, Alex Williamson wrote: > On Thu, 29 Jan 2026 21:24:51 +0000 > David Matlack wrote: > > +int __init vfio_pci_liveupdate_init(void) > > +{ > > + if (!liveupdate_enabled()) > > + return 0; > > + > > + return liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); > > +} > > liveupdate_register_file_handler() "pins" vfio-pci with a > try_module_get(). Since this is done in our module_init function and > unregister occurs in our module_exit function, rather than relative > to any actual device binding or usage, this means vfio-pci CANNOT be > unloaded. That seems bad. Thanks, Good point. So a better approach that would allow vfio-pci to be unloaded would be to register the file handler when the number of devices bound to vfio-pci goes from 0->1 and then unregister on 1->0.