Re: kernel panic when starting nfsd on OpenWrt with kernel 6.12.19

[Chuck Lever <chuck.lever@oracle.com>]

On 3/22/25 1:20 PM, John wrote:
> 
> 
> On Saturday, March 22nd, 2025 at 10:49 AM, Chuck Lever <chuck.lever@oracle.com> wrote:
>>
>> I recommend bisecting between 6.6 and 6.12.19 to locate the culprit.
>>
>> When you have that information, open a bug on bugzilla.kernel.org under
>> Filesystems/NFSD and attach your information there.
> 
> Wish I could, but the way OpenWrt is designed, moving from one kernel branch to another is major undertaking often requiring months of tweaks 1,000s of patches, Makefiles, config files, etc.
> 
> I have been reading up on NFSv4 and am wondering if there is a way to simply disable the callback function. Could that work-around this crash?
> 
> Unfortunately, OpenWrt's nfs-kernel-server package does not ship nor use something like /etc/nfs.conf. At the link below you can see their init script to start nfsd. Many thank for any ideas.
> 
> https://github.com/openwrt/packages/blob/master/net/nfs-kernel-server/files/nfsd.init
> 

If this is a "product" kernel then you should approach the distributor
first. I do not have the hardware, the binaries, the .config, or a
cross compiler for whatever "Hardware name: iKOOLCORE R2Max/R2Max" is
(guessing RPi ?)

It would be helpful to get

$ scripts/faddr2line fs/nfsd/nfs4callback.c \
nfsd4_probe_callback_sync+0x1094

although, IME, +1094 means the crash happened far outside of the
nfs4callback.c source file.

This:

  nfsd4_client_tracking_init+0x39/0x150 [nfsd]

suggests that your distributor (or LTS) might be missing a fix
for recent crashes that are due to incorrectly setting
CONFIG_NFSD_LEGACY_CLIENT_TRACKING. I'm thinking of perhaps

  de71d4e211ed ("nfsd: fix legacy client tracking initialization")

in particular, which does not appear to have been applied to
v6.12.19.


-- 
Chuck Lever