[Samsung Galaxy S7 (Exynos) ROMs, Kernels, Recoveri] lolthrash:
hey mate, any idea from this log why rooting wouldn't be working for me but seems to be for everyone else using the same steps on the same device?

Installing zip file '/sdcard/UPDATE-SuperSU-v2.65-20151226141550.zip'
Checking for MD5 file...
Skipping MD5 check: no MD5 file found
I:Zip does not contain SELinux file_contexts file in its root.
I:Legacy property environment initialized.

*****************
SuperSU installer
*****************
- Mounting /system, /data and rootfs
mount: mounting /dev/block/sda18 on /data failed: Device or resource busy
2+0 records in
2+0 records out
2 bytes (2B) copied, 0.004731 seconds, 422B/s
3+0 records in
3+0 records out
3 bytes (3B) copied, 0.000281 seconds, 10.4KB/s
10+0 records in
10+0 records out
10 bytes (10B) copied, 0.000181 seconds, 54.0KB/s
0+0 records in
0+0 records out
0 bytes (0B) copied, 0.000013 seconds, 0B/s
/tmp/updater: line 761: /system/toolbox: not found
- Extracting files
Archive: /sdcard/UPDATE-SuperSU-v2.65-20151226141550.zip
inflating: META-INF/MANIFEST.MF
inflating: META-INF/CERT.SF
inflating: META-INF/CERT.RSA
inflating: META-INF/com/google/android/update-binary
inflating: META-INF/com/google/android/updater-script
inflating: arm/chattr
inflating: arm/chattr.pie
inflating: arm/libsupol.so
inflating: arm/su
inflating: arm/sukernel
inflating: arm/supolicy
inflating: arm64/libsupol.so
inflating: arm64/su
inflating: arm64/sukernel
inflating: arm64/supolicy
inflating: armv7/chattr.pie
inflating: armv7/libsupol.so
inflating: armv7/su
inflating: armv7/sukernel
inflating: armv7/supolicy
inflating: common/99SuperSUDaemon
inflating: common/Superuser.apk
inflating: common/file_contexts_image
inflating: common/install-recovery.sh
inflating: common/launch_daemonsu.sh
inflating: mips/chattr.pie
inflating: mips/libsupol.so
inflating: mips/su
inflating: mips/sukernel
inflating: mips/supolicy
inflating: mips64/libsupol.so
inflating: mips64/su
inflating: mips64/sukernel
inflating: mips64/supolicy
inflating: x64/libsupol.so
inflating: x64/su
inflating: x64/sukernel
inflating: x64/supolicy
inflating: x86/chattr
inflating: x86/chattr.pie
inflating: x86/libsupol.so
inflating: x86/su
inflating: x86/su.pie
inflating: x86/sukernel
inflating: x86/supolicy
- Detecting system compatibility
sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/dev/block/sda5] ...

magic: [ANDROID!]
kernel: [32234880] (32235520) @ 0x10008000
ramdisk: [5290974] (5292032) @ 0x11000000
second: [0] (0) @ 0x10f00000
tags: @ 0x10000100
page size: 2048
unused: [0x000b3000] [0x00000000]
dtb(?): [733184] (733184)
name: [SRPOI17A000KU]
command line: []
extra command line: []
id: [0x8b2385cb697fd6b6f7eb4c7c1795fa0266af8d26000000000000000000000000]

Saving to [/sutmp/ramdisk.packed] ...

sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/sutmp/ramdisk.packed] ...

Decompressing [5290974] --> [10130432]

Saving to [/sutmp/ramdisk] ...

sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/sutmp/ramdisk] ...

----- patch check -----

Loading from cpio:[init.rc] ...

Finding [daemonsu]
-Found@1659 [service daemonsu /sbin/launch_daemonsu.sh]

Result: patched

- System-less mode, boot image support required
- Creating image
- Mounting image
- Creating paths
mkdir: can't create directory '/su/bin': File exists
mkdir: can't create directory '/su/xbin': File exists
mkdir: can't create directory '/su/lib': File exists
mkdir: can't create directory '/su/etc': File exists
mkdir: can't create directory '/su/su.d': File exists
- Removing old files
- Placing files
rm: can't remove '/su/bin/su': No such file or directory
rm: can't remove '/su/bin/daemonsu': No such file or directory
rm: can't remove '/su/bin/supolicy_wrapped': No such file or directory
rm: can't remove '/su/lib/libsupol.so': No such file or directory
rm: can't remove '/su/bin/sukernel': No such file or directory
rm: can't remove '/data/SuperSU.apk': No such file or directory
mkdir: can't create directory '/su/xbin_bind': File exists

******************
Boot image patcher
******************
- Finding boot image
--- Boot image: /dev/block/sda5
- Extracting ramdisk
sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/dev/block/sda5] ...

magic: [ANDROID!]
kernel: [32234880] (32235520) @ 0x10008000
ramdisk: [5290974] (5292032) @ 0x11000000
second: [0] (0) @ 0x10f00000
tags: @ 0x10000100
page size: 2048
unused: [0x000b3000] [0x00000000]
dtb(?): [733184] (733184)
name: [SRPOI17A000KU]
command line: []
extra command line: []
id: [0x8b2385cb697fd6b6f7eb4c7c1795fa0266af8d26000000000000000000000000]

Saving to [/sutmp/ramdisk.packed] ...

- Decompressing ramdisk
sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/sutmp/ramdisk.packed] ...

Decompressing [5290974] --> [10130432]

Saving to [/sutmp/ramdisk] ...

- Checking patch status
sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/sutmp/ramdisk] ...

----- patch check -----

Loading from cpio:[init.rc] ...

Finding [daemonsu]
-Found@1659 [service daemonsu /sbin/launch_daemonsu.sh]

Result: patched

--- Already patched, attempting to find stock backup
sukernel v2.65 (ndk:arm64-v8a) - Copyright (C) 2014-2015 - Chainfire

Loading from [/sutmp/ramdisk] ...

Loading from cpio:[init.rc] ...

Finding [^# SuperSU:STOCK:]
-Found@1666 [# SuperSU:STOCK:ac5c0729c79e6959d85e70d0152a6e1959bd8f93]

Stock boot image backup missing
--- Restore failed, aborting

*************************
IMPORTANT NOTICES
*************************
If TWRP offers to install
SuperSU, do *NOT* let it!
*************************
First reboot may take a
few minutes. It can also
loop a few times. Do not
interrupt the process!
*************************

- Unmounting /system
- Done !
I:Updater process ended with RC=0
I:Legacy property environment disabled.
Updating partition details...
I:Data backup size is 2973MB, free: 21958MB.
I:Unable to mount '/external_sd'
I:Actual block device: '', current file system: 'vfat'
I:Unable to mount '/usbstorage'
I:Actual block device: '', current file system: 'vfat'
...done
I:Set page: 'flash_done'
I:operation_end - status=0
I:Set page: 'clear_vars'
I:Set page: 'install'
I:Set page: 'main'
I:Set page: 'clear_vars'
I:Set page: 'main2'
I:Set page: 'advanced'
I:Set page: 'confirm_action'
I:Set page: 'action_page'
I:operation_start: 'Copy Log'
I:Copying file /tmp/recovery.log to /data/media/0/recovery.log