[Galaxy Note Pro 12.2 Original Android Development] esgie:
I assume that you have ran the command as root (ie didnt forget about 'su' before the main command)...? Your logs show non-root mode, but ur saying about '#' mode at the end, guess you mean su... Assume that all we do here requires root shell first to be opened, and the output even if similiar, may vary in details between non-root and root mode, so don't forget to get privileges before running anything below...

If so, I guess default policy prevents writing to /dev/kmem in enforcing mode by setting its selinux context to a special one, dedicated only for /dev/kmem and /dev/mem.The working solution is to repack kernel (not same, but, indeed, a lot easier, than recompile - changes won't affect the kernel binary code, but it's ramdisk part, only) with modified policy defaults, which will treat /dev/kmem as a genuine device, not a "sensitive" one. I can provide the one repacked for my own purposes, however, befoure such an intrusion we may want to try other solutions I can think of (again, cannot test it as I ve added many different mods in many different places, I would need to go back to stock to test it, but I need my device 100% steady and configured for my job this week. Hope you'll help me in solving this out, it shouldnt take long...).

Notice: Again, ALL BELOW COMMANDS SHOULD BE RUN IN ROOT MODE. That means you shall enter "su" command alone before trying any of those steps, and the Terminal will switch to a root shell, which is confirmed by switching the last sign in the prompt from '$' to '#'.

Notice 2: if it is written - after some steps - to try switching to permissive mode again, it should be done by running the command from MY PREVIOUS POST only, as it is equal to longer version from the script, just closed within shorter one-liner command... the command should change the mode to permissive itself and no further steps are needed.

1) run following:

ls -lZ /dev/kmem >/sdcard/info.txt

and paste the exact output (which has been saved at /sdcard/info.txt) here so I can gather further info about issue. Dont make a test of the main script here as nothing has been changed. After that...

2) we can try to set different context (a default one for dev files) manually. Again, it might be impossible as of selinux policy, but worth trying. Enter as root:

busybox mount -o rw,remount /
chcon u:object_r:device:s0 /dev/kmem

if error, paste it here. If no error, test if permissive mode script is working.

3) we can try to modify selinux policy in temporary ramdisk file to prevent giving /dev/kmem a special context and then restore context of whole /dev to it's "defaults", however, those "defaults" would be our modified ones. Possible issues: not sure if the restoring default context will make use of modified policy or would it use only the policy loaded on-boot (and as the ramdisk is temporary, policy modifications will disappear too within reboot). After getting root, enter:

busybox mount -o rw,remount /
sed -i "s:^.*\/dev\/[k]*mem.*$::g" /file_contexts
setprop selinux.reload_policy 1
restorecon -R /dev >/dev/null 2>&1

after that - if no errors - check if the switching works.

4) if none of the above is working, guess we'll need to repack stock kernel with a ramdisk content modified in the same way as in step 3. When embedded in kernel, the changes to the policy rules will be seen every boot and they will affect /dev/kmem in a persistent manner. This will let you write to it for sure. I will provide a ready repacked boot.img, so we can avoid repacking at all. This however is not a very satisfying solution, as my goal was not only to achieve permissive mode, but to achieve it without any changes (even if they are much less disturbing than recompiling kernel from source) to boot partition. But hey, first check out on-the-fly solutions above, as they are much less intrusive to a device, coz won't require reflashing kernel/boot partition.

EDIT: remount command added to step 2, repeat if you had error with changing the context.

Thanks for your effort.