FS#2047 - Swap kernel option doesn't work and /proc/swap endpoint is absent on ar71xx device

[openwrt-bot]

alexfv:

Device: TP-LINK TL-MR3420 v2 with replaced NAND flash chip (8MB ROM now) + USB hub with external power + 8Gb flash drive + 1Tb USB hdd
OpenWRT version: Trunk, OpenWrt GCC 7.4.0 r8982-a54129d
Steps to reproduce:

1. Install block-mount and swap-utils
2. Create swap partition and try to enable it

root@OpenWrt:# mkswap /dev/sdb2
mkswap: /dev/sdb2: warning: wiping old swap signature.
Setting up swapspace version 1, size = 256 MiB (268431360 bytes)
no label, UUID=3068f953-a060-41cd-a09b-bcc2c531bf40
root@OpenWrt:# swapon /dev/sdb2
block: failed to swapon /dev/sdb2 (-1)

3. Try to get /proc/swaps file

root@OpenWrt:~# cat /proc/swaps
cat: can't open '/proc/swaps': No such file or directory

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"dmesg" output is attached.

[openwrt-bot]

Platinum_Dragon:

Got same issue on TL-MR3220 v2 OpenWrt SNAPSHOT r8996-634c733065

[openwrt-bot]

ynezz:

To me it looks like it's not a bug, both devices have small flash (firmware images for tiny TP Link devices) and for this devices is swap disabled to save some flash space.