On Mon, Jul 20, 2020 at 05:58:44PM +0200, Christoph Hellwig wrote:

Add a simple helper for a chdir with a kernelspace name and use it in the
early init code instead of relying on the implicit set_fs(KERNEL_DS)
there.  Remove the now unused ksys_chdir.

FWIW, my problem with that is that you are making it first-class primitive.
And I don't see any valid use for it - existing one is really "we have
a userland process that would be making syscalls if we only could have it
done right; the only reason we can't is that the infrastructure to build
the binary would be hell to maintain in the tree".  It's *NOT* "kernel
code that has a valid reason to get the syscall functionality".