[Magisk] ivanich:
An installation log (recovery or Manager) plus a copy of your boot image might help with the debugging.

recovery.log

Installing zip file '/sdcard/MagiskManager/Magisk-v15.1.zip'
Checking for Digest file...
Skipping Digest check: no Digest file found
I:Update binary zip
I:Zip does not contain SELinux file_contexts file in its root.
I:Legacy property environment not used in updater.
Archive: /sdcard/MagiskManager/Magisk-v15.1.zip
inflating: META-INF/com/google/android/update-binary
inflating: META-INF/com/google/android/updater-script
inflating: addon.d/99-magisk.sh
inflating: arm/magiskboot
inflating: arm/magiskinit
inflating: arm64/magiskboot
inflating: arm64/magiskinit
inflating: chromeos/futility
inflating: chromeos/kernel.keyblock
inflating: chromeos/kernel_data_key.vbprivk
inflating: common/boot_patch.sh
inflating: common/magisk.apk
inflating: common/util_functions.sh
inflating: x64/magiskboot
inflating: x64/magiskinit
inflating: x86/magiskboot
inflating: x86/magiskinit
inflating: META-INF/MANIFEST.MF
inflating: META-INF/CERT.SF
inflating: META-INF/CERT.RSA
************************
* Magisk v15.1 Installer
************************
- Mounting /system, /vendor
- Device platform: arm64
- Constructing environment
mv: can't rename '/data/magisk.img': No such file or directory
- Found boot image: /dev/block/sde18
Signature is VALID
- Signed boot image detected
- Encrypted data detected
- Unpacking boot image
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Parsing boot image: [/dev/block/sde18]
KERNEL [13288268] @ 0x80008000
RAMDISK [2683727] @ 0x81000000
SECOND [0] @ 0x80f00000
EXTRA [0] @ 0x80000100
PAGESIZE [4096]
OS_VERSION [8.0.0]
PATCH_LEVEL [2017-12]
NAME []
CMDLINE [androidboot.hardware=qcom user_debug=31 msm_rtb.filter=0x237 ehci-hcd.park=3 lpm_levels.sleep_disabled=1 cma=32M@0-0xffffffff buildvariant=user]
DTB [4393782]
KERNEL_FMT [gzip]
RAMDISK_FMT [gzip]
- Checking ramdisk status
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Loading cpio: [ramdisk.cpio]
- Stock boot image detected
- Backing up stock boot image
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Compressing to [stock_boot_bd2c05611343c4cdaa541e0b6f40c52a79d67a14.img.gz]
- Patching ramdisk
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Loading cpio: [ramdisk.cpio]
Add entry [init] (0750)
Patch with flag KEEPVERITY=[false] KEEPFORCEENCRYPT=[true]
Remove [verity_key]
Save SHA1: [bd2c05611343c4cdaa541e0b6f40c52a79d67a14] -> [.backup/.sha1]
Loading cpio: [ramdisk.cpio.orig]
Backup mismatch entry: [init] -> [.backup/init]
Backup missing entry: [verity_key] -> [.backup/verity_key]
Dump cpio: [ramdisk.cpio]
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Loading dtbs from [dtb]
Found fstab in dtb.0000
Found block [system] in fstab
Remove pattern [,verify]
libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x7bb50003a0 in tid 756 (magiskboot)
Segmentation fault
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Patch @ 01309BE6 [736B69705F696E697472616D6673]->[77616E745F696E697472616D6673]
- Repacking boot image
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Parsing boot image: [/dev/block/sde18]
KERNEL [13288268] @ 0x80008000
RAMDISK [2683727] @ 0x81000000
SECOND [0] @ 0x80f00000
EXTRA [0] @ 0x80000100
PAGESIZE [4096]
OS_VERSION [8.0.0]
PATCH_LEVEL [2017-12]
NAME []
CMDLINE [androidboot.hardware=qcom user_debug=31 msm_rtb.filter=0x237 ehci-hcd.park=3 lpm_levels.sleep_disabled=1 cma=32M@0-0xffffffff buildvariant=user]
DTB [4393782]
KERNEL_FMT [gzip]
RAMDISK_FMT [gzip]
Repack to boot image: [new-boot.img]
KERNEL [13295289] @ 0x80008000
RAMDISK [3062988] @ 0x81000000
SECOND [0] @ 0x80f00000
EXTRA [0] @ 0x80000100
PAGESIZE [4096]
OS_VERSION [8.0.0]
PATCH_LEVEL [2017-12]
NAME []
CMDLINE [androidboot.hardware=qcom user_debug=31 msm_rtb.filter=0x237 ehci-hcd.park=3 lpm_levels.sleep_disabled=1 cma=32M@0-0xffffffff buildvariant=user]
MagiskBoot v15.1(1510) (by topjohnwu) - Boot Image Modification Tool
Cleaning up...
- Flashing new boot image
- Unmounting partitions
- Done
I:Updater process ended with RC=0
I:Install took 27 second(s).
Updating partition details...
I:Data backup size is 7127MB, free: 25833MB.
I:Unable to mount '/usb_otg'
I:Actual block device: '', current file system: 'vfat'
...done
I:Set page: 'flash_done'
I:operation_end - status=0

Stock, backedup boot.img https://drive.google.com/open?id=1Di7NPAEbhcHZr7UUR7FRfsfCvFPR28V9

I believe this is the reason

Found fstab in dtb.0000
Found block [system] in fstab
Remove pattern [,verify]
libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x7bb50003a0 in tid 756 (magiskboot)
Segmentation fault