NFS rootfs fails on 3.16

[ZubairLK]

Tested buildroot filesystem.
Same rootfs works via sd card.
Same nfs export mounts via nfs rootfs using 3.0.8
Same nfs export mounts via terminal in 3.16 once booted using mmc.

Bootlog here
http://pastebin.com/yVKyFiQ8

Bootargs
setenv bootargs console=ttyS4,115200 console=ttyS0 mem=256M@0x0 mem=768M@0x30000000 root=/dev/nfs nfsroot=192.168.154.89:/export,nfsvers=3,nolock nfsrootdebug ip=dhcp devtmpfs.mount=1 rw rootwait

[ZubairLK]

Disabling CONFIG_HIGHMEM in kernel options results in a working nfs mount and it works.

bootargs.

console=ttyS4,115200 console=ttyS0 mem=256M@0x0 root=/dev/nfs nfsroot=192.168.154.89:/export,nolock nfsrootdebug ip=dhcp devtmpfs.mount=1 rw rootwait clk_ignore_unused

Disabling HIGHMEM is not a fix. But a workaround. The actual bug is somewhere in highmem/cache.

Found similar bug when trying to boot NAND rootfs using 3.16.
Init would fail.

Booting 3.16 via a rootfs using mmc would work. Then ubiattach /dev/mtd3 would work too.
Mounting partition would work too. But trying to execute any binary in the partition would give random errors.
i.e.

ubiattach /dev/ubi_ctrl -m 3
mount -t ubifs ubi0:root /media/
cd /media/bin
./ls
illegal instruction
./ls
seg fault

errors like this

Trying again and again would result in it working after a while.

This is what happens during init. It is not an init bug. The binary doesn't execute when the NAND block device is mounted.

[ZubairLK]

#18