Guillermo:
The problem seems to be those whose corresponding array of iovecs doesn't have a 'from' element,
I hit this with cgroupfs and tmpfs in version 1.28 and thought that it was just specific to those filesystem types. The reason that I never hit it with procfs, devtmpfs, and sysfs is actually tied in to your other problem.
Guillermo:
And the catch-all logger reports this:
Reading the logs is always a good thing, I have found. In this case, it meant that I knew what was going on in just a couple of minutes. Otherwise I'd be wondering why this worked in my system when I bootstrapped into the older Debian 8 kernel to test what happens when only v1 control groups are available, but it didn't work for you.
Debian's initramfs mounts /proc, /sys, /run, and a whole lot of other stuff before /sbin/init is run. Yours does not. I see far more messages in my log than you do. So:
1. There's a chicken-and-egg situation with having to read /proc/filesystems in order to determine what API filesystems can be mounted. Good old Linux, eh?
2. The procfs, devtmpfs, and sysfs problems did exist, but I never hit them because on Debian they had already been mounted with a "from" name.
I've already fixed the "from" problem ready for 1.32. I'll have a go at fixing the other one, too. There are simply going to have to be two phases of API filesystem mounting. Three on Debian. (-: