On 12/1/25 9:44 AM, Pasha Tatashin wrote:
On Mon, Dec 1, 2025 at 12:36 PM David Matlack dmatlack@google.com 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 yanjun.zhu@linux.dev 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.