Can't remount /system in rw I try desesperately to push an app with adb  on the /system/app folder (to install the PlayStore on my low cost tablet).
So i tried to remount the /system partition with root rights :

mount -o remount,rw /system 


But it give me everytimes the same response : 

mount: Read-only filesystem


And i tried also with this command :

mount -o remount,rw -t ext4 /dev/block/actc /system 

but it's the same thing...
And i don't understand really why, even with the root user, i can't modify this...

So if someone have an idea, it could be save one person in distress :p
The syntax of mount command usually requires you specify the target:

mount -o remount,rw /system /system


This output could be useful for us to better understand your problem:

cat /proc/mounts


As a last resort, as you have root you can try saving raw image of system, mount it on your box and push the app there, then flash it back on your device. To save raw system image:

dd if=&lt;block device mounted on /system&gt; of=&lt;output file&gt;


If you go that way make sure you keep the original system image in case something goes wrong.