depmod: ERROR: Found 2 modules in dependency cycles -- ERROR: Cycle detected: lnet -> libcfs -> lnet

http://linux-kernel.2935.n7.nabble.com/next-20151101-depmod-issues-with-Lustre-modules-td1230262.html

Linus Torvalds-2

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Nov 08, 2015; 5:50am

Re: next-20151101 - depmod issues with Lustre modules

7819 posts

On Sat, Nov 7, 2015 at 12:37 PM, Dmitry Safonov <[hidden email]> wrote:
> Reproduced on mainline v4.3-9038-g27eb427bdc0960 with
> Arch Linux default config (attached):
>
> depmod: ERROR: Found 2 modules in dependency cycles!
> depmod: ERROR: Cycle detected: lnet -> libcfs -> lnet
> make: *** [_modinst_post] Error 1

The reason seems to be that

 - lnet.ko provides the following functions needed by libcfs.ko:

    libcfs_next_nidstring
    libcfs_nid2str_r

 - libcfs.ko provides the following functions needed by lnet.ko:

    libcfs_debug
    libcfs_debug_msg
    libcfs_deregister_ioctl
    libcfs_register_ioctl
    libcfs_subsystem_debug
    lustre_insert_debugfs

but I may have messed up something.

Anyway, the problem seems to be that - insanely - lnet.ko provides
those libcfs nid handling functions. They should be in libcfs, as far
as I can tell, just judging by the name. Also judging by the use.

The cause seems to be commit 47ca6ec2673e ("staging: lustre: move
nidstring handling to LNet layer") by James Simmons.

I do wonder if linux-next could perhaps do some modprobe testing too?

                      Linus
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