MIUI10上挂载system分区失败

[shuyuan-liu]

现象

root方式安装hosts时最后一步失败，错误信息：挂载/system分区失败: mount: '/system' not in /proc/mounts。
ADB运行mount -o rw,remount /system报同样错误。

系统配置

小米9SE

• 系统：MIUI 10 9.7.11开发版
• 内核：4.9.112-perf-g7fa7844
• root：Magisk 19.4 (19305)

其他应用能正常挂载/system

FX文件管理器中开启ROOT功能后能正常挂载/system为读写，并能用文本编辑器编辑/etc/hosts及/system/etc/hosts并成功保存。

mount输出

/dev/root on / type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
tmpfs on /sbin type tmpfs (rw,seclabel,relatime,size=2857844k,nr_inodes=714461,mode=755)
/sbin/.magisk/block/system_root on /sbin/.magisk/mirror/system_root type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /sbin/charger type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /sbin/setlockstate type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
tmpfs on /dev type tmpfs (rw,seclabel,nosuid,relatime,size=2857844k,nr_inodes=714461,mode=755)
devpts on /dev/pts type devpts (rw,seclabel,relatime,mode=600,ptmxmode=000)
proc on /proc type proc (rw,relatime,gid=3009,hidepid=2)
sysfs on /sys type sysfs (rw,seclabel,relatime)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
tmpfs on /mnt type tmpfs (rw,seclabel,nosuid,nodev,noexec,relatime,size=2857844k,nr_inodes=714461,mode=755,gid=1000)
/dev/block/sde48 on /vendor type ext4 (ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr)
none on /acct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct)
debugfs on /sys/kernel/debug type debugfs (rw,seclabel,relatime)
none on /dev/stune type cgroup (rw,nosuid,nodev,noexec,relatime,schedtune)
none on /config type configfs (rw,nosuid,nodev,noexec,relatime)
none on /dev/cpuctl type cgroup (rw,nosuid,nodev,noexec,relatime,cpu)
none on /dev/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset,noprefix,release_agent=/sbin/cpuset_release_agent)
cg2_bpf on /dev/cg2_bpf type cgroup2 (rw,nosuid,nodev,noexec,relatime)
bpf on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime)
pstore on /sys/fs/pstore type pstore (rw,seclabel,nosuid,nodev,noexec,relatime)
none on /sys/fs/cgroup type tmpfs (rw,seclabel,relatime,size=2857844k,nr_inodes=714461,mode=750,gid=1000)
none on /sys/fs/cgroup/memory type cgroup (rw,relatime,memory)
none on /sys/fs/cgroup/freezer type cgroup (rw,relatime,freezer)
tracefs on /sys/kernel/debug/tracing type tracefs (rw,seclabel,relatime)
/dev/block/sda29 on /data type ext4 (rw,lazytime,seclabel,nosuid,nodev,noatime,noauto_da_alloc,resgid=1065,data=ordered)
/dev/block/sda27 on /cache type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered)
/dev/block/sde47 on /vendor/firmware_mnt type vfat (ro,context=u:object_r:firmware_file:s0,relatime,gid=1000,fmask=0337,dmask=0227,codepage=437,iocharset=iso8859-1,shortname=lower,errors=remount-ro)
/dev/block/sde42 on /vendor/dsp type ext4 (ro,seclabel,nosuid,nodev,relatime,data=ordered)
/dev/block/sda22 on /mnt/vendor/persist type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered)
/dev/block/sde23 on /vendor/bt_firmware type vfat (ro,context=u:object_r:bt_firmware_file:s0,relatime,uid=1002,gid=3002,fmask=0337,dmask=0227,codepage=437,iocharset=iso8859-1,shortname=lower,errors=remount-ro)
/dev/block/sda14 on /dev/logfs type vfat (rw,noatime,uid=1000,gid=1000,fmask=0006,dmask=0006,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/block/sda28 on /cust type ext4 (ro,seclabel,nosuid,nodev,noatime,data=ordered)
tmpfs on /storage type tmpfs (rw,seclabel,nosuid,nodev,noexec,relatime,size=2857844k,nr_inodes=714461,mode=755,gid=1000)
/sbin/.magisk/block/vendor on /sbin/.magisk/mirror/vendor type ext4 (ro,seclabel,relatime,block_validity,discard,delalloc,barrier,user_xattr)
/sbin/.magisk/block/data on /sbin/.magisk/mirror/data type ext4 (rw,lazytime,seclabel,relatime,noauto_da_alloc,resgid=1065,data=ordered)
/sbin/.magisk/block/data on /sbin/.magisk/modules type ext4 (rw,lazytime,seclabel,relatime,noauto_da_alloc,resgid=1065,data=ordered)
tmpfs on /system/xbin type tmpfs (rw,seclabel,relatime,size=2857844k,nr_inodes=714461)
/sbin/.magisk/block/data on /system/xbin/busybox type ext4 (rw,lazytime,seclabel,relatime,noauto_da_alloc,resgid=1065,data=ordered)
/sbin/.magisk/block/system_root on /system/xbin/system_perf_init type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/mqsasd type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/procrank type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/miuibooster type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/procmem type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/miuioneshots type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/shelld type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/mfd type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
/sbin/.magisk/block/system_root on /system/xbin/msc type ext4 (ro,seclabel,relatime,block_validity,delalloc,barrier,user_xattr)
adb on /dev/usb-ffs/adb type functionfs (rw,relatime)
none on /dev/blkio type cgroup (rw,relatime,blkio)
/data/media on /mnt/runtime/default/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=1015,multiuser,mask=6,derive_gid,default_normal)
/data/media on /storage/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=1015,multiuser,mask=6,derive_gid,default_normal)
/data/media on /mnt/runtime/read/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=23,derive_gid,default_normal)
/data/media on /mnt/runtime/write/emulated type sdcardfs (rw,nosuid,nodev,noexec,noatime,fsuid=1023,fsgid=1023,gid=9997,multiuser,mask=7,derive_gid,default_normal)