Stupid question bout the interaction of initramfs, hotplug, and per-process
filesystem namespaces:
I do this from initramfs:
echo /sbin/mdev > /proc/sys/kernel/hotplug
At the moment I do that, the first "/" in /sbin/mdev points to rootfs.
Shortly thereafter I do a switch_root, which does a chroot. Does hotplug
still point into rootfs? Or does it point to whatever "/" for PID 1 points
to now?
Since every process could be in a different chroot environment, how do I know
which process context the kernel_thread that call_usermodehelper() runs in
was parented from? It seems random: the x86 implementation of
call_usermodehelper() is calling do_fork(), and seems to be using the
namespace of whatever process it's running in. Which could be a chroot
process that doesn't have the hotplug I pointed it at visible in its
namespace at all...
Anybody know this one? Now that filesystem namespaces are per-process, and
move/bind mounts let us have cycles in our trees, as far as I can tell we
could actually have two completely detached namespaces with different sets of
processes in each. A path to hotplug isn't
Rob
P.S: mount a filesystem under itself. Fun for the whole family:
mount -t tmpfs /tmp /tmp
cd /tmp
mkdir sub
mount --bind sub /var
cd /var
mkdir sub2
mount --move /tmp sub2
--
Never bet against the cheap plastic solution.
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