(/proc/kcore) What is this magical file which can somehow take up 140.7 TB on a 500 GB HDD?

Question

I was cramped for hard drive space, so I was looking for a place where some files might have been duplicated during a restore. The culprit turned out to be root trash, but this stuck out like a sore thumb.

This Page says that the file is an alias for my memory and the size of the file is the same as the amount of RAM that I have.

Now that can't be entirely true, because I only have 4.0 GB of RAM.

What is going on here?

Solution

This file is not as big as the amount of RAM installed in your system but instead it is as big as the address space that Linux could potentually address at max.

This doesn't mean that this file uses any actual space at all, it is just a virtual file presented by the Linux kernel, as are all files in the /proc tree.

You can find a more detailed description regarding the address space in this post.