Re: Is initramfs freed after kernel is booted?

["Kevin P. Fleming" <kpfleming@backtobasicsmgmt.com>]

Chris Friesen wrote:

> Absolutely, the memory should be reclaimed.  I would have thought that 
> you could just unmount it--if the pivot_root is done properly there 
> shouldn't be any references left to the initramfs.

There is no pivot_root happening here; the kernel creates a ramfs and 
mounts it on / (as rootfs), then unpacks the initramfs cpio archive into 
it. After doing a few more steps, it overmounts the real root onto /, 
making the rootfs filesystem invisible. It is not freed in the current 
kernels.

I suspect that if you wanted to modify init/do_mounts.c, you could use 
the initrd technique of doing the pivot_root yourself (instead of 
letting the kernel automount the "real" root filesystem), at which point 
it maybe be possible to umount and free the rootfs.