[BISECT BUG] NFS v4 root not working after 6d972518b821 ("NFS: Add fs_context support.")

[Krzysztof Kozlowski]

Hi all,

Bisect pointed to 6d972518b821 ("NFS: Add fs_context support.") for
failures of mounting NFS v4 root on my boards:
mount.nfs4 -o vers=4,nolock 192.168.1.10:/srv/nfs/odroidhc1 /new_root
[ 24.980839] NFS4: Couldn't follow remote path
[ 24.986201] NFS: Value for 'minorversion' out of range
mount.nfs4: Numerical result out of range

https://krzk.eu/#/builders/21/builds/1692
Full console log:
https://krzk.eu/#/builders/21/builds/1692/steps/14/logs/serial0

Enabling NFS v4.1 in defconfig seems to help. I can send patches for
this (for defconfigs) but probably the root cause should be fixed as
well.

Environment:
1. Arch ARM Linux
2. exynos_defconfig
3. Exynos boards (Odroid XU3, etc), ARMv7, octa-core (Cortex-A7+A15),
Exynos5422 SoC
4. systemd, boot up with static IP set in kernel command line
5. No swap
6. Kernel, DTB and initramfs are downloaded with TFTP
7. NFS root from NFSv4 server

Let me know if you need more details.

Best regards,
Krzysztof