Invoking load_module() before param_sysfs_init() is called crashes in
mod_sysfs_setup(), since the kset in module_subsys is not initialized yet.
In my case, net-pf-1 is getting modprobed as a result of hotplug trying to
create a UNIX socket. Calls to hotplug begin after the topology_init
initcall.
Another patch for the same symptom (module_subsys-initialize-earlier.patch)
moves param_sysfs_init() to the subsys initcalls, but this is still not
early enough in the boot process in some cases. In particular,
topology_init() causes /sbin/hotplug to run, which requests net-pf-1 (the
UNIX socket protocol) which can be compiled as a module. Moving
param_sysfs_init() to the postcore initcalls fixes this particular race,
but there might well be other cases where a usermodehelper causes a module
to load earlier still.
The patch makes load_module() return an error rather than crashing the
kernel if invoked before module_subsys is initialized.
Cc: Mark Huang <mlhuang@cs.princeton.edu>
Cc: Greg KH <greg@kroah.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1cc5f7142e