From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC15D1F5858; Mon, 1 Dec 2025 21:45:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764625559; cv=none; b=mkGdnBZBWWt7Hr9S27LmQ5eBJXA/AWPI6IMUZXunFRHu8l5ygPJZwnpBbDFcM0Vmaoe7OqSgnuwKS0N6STMaOC80gQNXs7nP8m7iaTalxqJYLtXZPLcvkPGogRzV5WLH7MvREmo1482iBxgbOhnYqnQYntTKVeGeJwZ7lCEUKKk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764625559; c=relaxed/simple; bh=WcbHVBU4VUz1jFu5FwY/JEuEetn2be/vIWHXZbdKoyk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FxgSto1z04J49RP/4GI0CGZeZYcOOAyqfaZRGUFwq+gD5I/qspDP5d+nPuPRaJDzAZ7ZbI/UrnvlzWQWaI33iVmNShqStijQmGMR+7o5x8ndqy1GMpoLl/HqHYtBHDlq3P/BndYSJOOeLjxSrkKrrXbpDfBbsxKcFbAvJhuzimQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=jXDCbhL/; arc=none smtp.client-ip=95.215.58.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="jXDCbhL/" Message-ID: <3aa3a726-147d-4573-ae50-eef94a910640@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1764625553; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+qUB0u+oB2O9DsJi+l+u21txGWUQE8jXEd7AAEA4kro=; b=jXDCbhL/q9tuznj0wml1Vt6q33yeBEVAgEBDcgJyoiP7m3c2e9Dx+DVDyZFqhVk3+jCa4A q+bRhiMJNrRhAm+Uo/+wwtPIceRnL3BYDqD6kO94C8KlyIUuAKJMWYNEGr2Ua68J0xBkCJ 1Pk3nZunxXF1eU9o8Ek//NlZKq+/qgg= Date: Mon, 1 Dec 2025 13:45:40 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 00/21] vfio/pci: Base support to preserve a VFIO device file across Live Update To: Pasha Tatashin , David Matlack Cc: Alex Williamson , Adithya Jayachandran , Alex Mastro , Alistair Popple , Andrew Morton , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Josh Hilke , Kevin Tian , kvm@vger.kernel.org, Leon Romanovsky , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-pci@vger.kernel.org, Lukas Wunner , Mike Rapoport , Parav Pandit , Philipp Stanner , Pratyush Yadav , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Tomita Moeko , Vipin Sharma , William Tu , Yi Liu , Yunxiang Li References: <20251126193608.2678510-1-dmatlack@google.com> <46bbdad1-486d-4cb1-915f-577b00de827f@linux.dev> <4998497c-87e8-4849-8442-b7281c627884@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Yanjun.Zhu" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 12/1/25 9:44 AM, Pasha Tatashin wrote: > On Mon, Dec 1, 2025 at 12:36 PM David Matlack wrote: >> On 2025-12-01 05:32 PM, David Matlack wrote: >>> On 2025-12-01 09:16 AM, Zhu Yanjun wrote: >>>> 在 2025/12/1 9:10, David Matlack 写道: >>>>> On Mon, Dec 1, 2025 at 7:49 AM Zhu Yanjun wrote: >>>>>> 在 2025/11/27 20:56, Zhu Yanjun 写道: >>>>>>> Hi, David >>>>>>> >>>>>>> ERROR: modpost: "liveupdate_register_file_handler" [drivers/vfio/pci/ >>>>>>> vfio-pci-core.ko] undefined! >>>>>>> >>>>>>> ERROR: modpost: "vfio_pci_ops" [drivers/vfio/pci/vfio-pci-core.ko] >>>>>>> undefined! >>>>>>> ERROR: modpost: "liveupdate_enabled" [drivers/vfio/pci/vfio-pci-core.ko] >>>>>>> undefined! >>>>>>> ERROR: modpost: "liveupdate_unregister_file_handler" [drivers/vfio/pci/ >>>>>>> vfio-pci-core.ko] undefined! >>>>>>> ERROR: modpost: "vfio_device_fops" [drivers/vfio/pci/vfio-pci-core.ko] >>>>>>> undefined! >>>>>>> ERROR: modpost: "vfio_pci_is_intel_display" [drivers/vfio/pci/vfio-pci- >>>>>>> core.ko] undefined! >>>>>>> ERROR: modpost: "vfio_pci_liveupdate_init" [drivers/vfio/pci/vfio- >>>>>>> pci.ko] undefined! >>>>>>> ERROR: modpost: "vfio_pci_liveupdate_cleanup" [drivers/vfio/pci/vfio- >>>>>>> pci.ko] undefined! >>>>>>> make[4]: *** [scripts/Makefile.modpost:147: Module.symvers] Error 1 >>>>>>> make[3]: *** [Makefile:1960: modpost] Error 2 >>>>>>> >>>>>>> After I git clone the source code from the link https://github.com/ >>>>>>> dmatlack/linux/tree/liveupdate/vfio/cdev/v1, >>>>>>> >>>>>>> I found the above errors when I built the source code. >>>>>>> >>>>>>> Perhaps the above errors can be solved by EXPORT_SYMBOL. >>>>>>> >>>>>>> But I am not sure if a better solution can solve the above problems or not. >>>>>> I reviewed this patch series in detail. If I’m understanding it >>>>>> correctly, there appears to be a cyclic dependency issue. Specifically, >>>>>> some functions in kernel module A depend on kernel module B, while at >>>>>> the same time certain functions in module B depend on module A. >>>>>> >>>>>> I’m not entirely sure whether this constitutes a real problem or if it’s >>>>>> intentional design. >>>>> Thanks for your report. Can you share the .config file you used to >>>>> generate these errors? >>>> >>>> IIRC, I used FC 42 default config. Perhaps you can make tests with it. If >>>> this problem can not be reproduced, I will share my config with you. >>>> >>> What does "FC 42 default config" mean? >>> >>> Either way I was able to reproduce the errors you posted above by >>> changing CONFIG_VFIO_PCI{_CORE} from "y" to "m". >>> >>> To unblock building and testing this series you can change these configs >>> from "m" to "y", or the following patch (which fixed things for me): >> Oops, sorry, something went wrong when I posted that diff. Here's the >> correct diff: >> >> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile >> index 929df22c079b..c2cca16e99a8 100644 >> --- a/drivers/vfio/pci/Makefile >> +++ b/drivers/vfio/pci/Makefile >> @@ -2,11 +2,11 @@ >> >> vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o >> vfio-pci-core-$(CONFIG_VFIO_PCI_ZDEV_KVM) += vfio_pci_zdev.o >> -vfio-pci-core-$(CONFIG_LIVEUPDATE) += vfio_pci_liveupdate.o >> obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o >> >> vfio-pci-y := vfio_pci.o >> vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o >> +vfio-pci-$(CONFIG_LIVEUPDATE) += vfio_pci_liveupdate.o >> obj-$(CONFIG_VFIO_PCI) += vfio-pci.o >> >> obj-$(CONFIG_MLX5_VFIO_PCI) += mlx5/ >> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c >> index c5b5eb509474..b9805861763a 100644 >> --- a/drivers/vfio/vfio_main.c >> +++ b/drivers/vfio/vfio_main.c >> @@ -1386,6 +1386,7 @@ const struct file_operations vfio_device_fops = { >> .show_fdinfo = vfio_device_show_fdinfo, >> #endif >> }; >> +EXPORT_SYMBOL_GPL(vfio_device_fops); >> >> /** >> * vfio_file_is_valid - True if the file is valid vfio file >> diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c >> index 69298d82f404..c7a0c9c3b6a8 100644 >> --- a/kernel/liveupdate/luo_core.c >> +++ b/kernel/liveupdate/luo_core.c >> @@ -256,6 +256,7 @@ bool liveupdate_enabled(void) >> { >> return luo_global.enabled; >> } >> +EXPORT_SYMBOL_GPL(liveupdate_enabled); >> >> /** >> * DOC: LUO ioctl Interface >> diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c >> index fca3806dae28..9baa88966f04 100644 >> --- a/kernel/liveupdate/luo_file.c >> +++ b/kernel/liveupdate/luo_file.c >> @@ -868,6 +868,7 @@ int liveupdate_register_file_handler(struct liveupdate_file_handler *fh) >> luo_session_resume(); >> return err; >> } >> +EXPORT_SYMBOL_GPL(liveupdate_register_file_handler); >> >> /** >> * liveupdate_unregister_file_handler - Unregister a liveupdate file handler >> @@ -913,3 +914,4 @@ int liveupdate_unregister_file_handler(struct liveupdate_file_handler *fh) >> liveupdate_test_register(fh); >> return err; >> } >> +EXPORT_SYMBOL_GPL(liveupdate_unregister_file_handler); Sure. Exactly. The above is the same with my solution. But after that EXPORT_SYMBOL_GPL, a cyclic dependency issue will occur. Yanjun.Zhu > Please add the EXPORT_SYMBOL_GPL() to the public LUO API as needed, I > was asked to stay conservative and not export until it is actually > needed by modules.