Re: Problems module autoload in 2.6.x

From: Thomas Steudten
Date: Tue Mar 30 2004 - 14:42:54 EST


What I see:
In 2.4.x the modprobe has option -k [..], which
is set in the request_module() in kmod.c.
Also the string "(autoclean)" is printed for
lsmod, if the module was loaded with the -k
option for modprobe from the kernel.
The string is coded in the module.c in 2.4.x.

In kernel 2.6.x, I use 2.6.4, the option -k to
modprobe is gone. Also the request_module() call
in the kernel source, don´t set this option.
The lsmod or cat /proc/modules don't gives
the string "(autoclean)" any more. But that's
another point, don't know why this is gone..

What I have done to trace this down:
I have add a printk to the request_module()
call, to see what is happen there.

If I call mdir a:, the floppy module
isn´t requested in request_module().
Same problem for modules
- lp
- floppy
- loop

I thought if there's no request_module() call
in the kernel next to this module, the generic
one in

genhd.c for block devices and
static struct kobject *base_probe(dev_t dev, int *part, void *data)
printk( KERN_ERR "base_probe: enter %d %d\n",MAJOR(dev), MINOR(dev));
if (request_module("block-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
/* Make old-style 2.4 aliases work */
request_module("block-major-%d", MAJOR(dev));
return NULL;
misc.c for char devices
static int misc_open(struct inode * inode, struct file * file)
int minor = iminor(inode);
struct miscdevice *c;
int err = -ENODEV;
struct file_operations *old_fops, *new_fops = NULL;


list_for_each_entry(c, &misc_list, list) {
if (c->minor == minor) {
new_fops = fops_get(c->fops);

if (!new_fops) {
request_module("char-major-%d-%d", MISC_MAJOR, minor);

But the modules aren't never requested. What is going wrong here?
I just wonder, that nobody but me has this problem.
Another point to the missing autoload feature, is the autoclean support
for modules. Why is this gone?

Please CC: me.

2.6.4 on alpha:

zgrep -i mod /proc/config.gz
# Loadable module support

grep -i floppy /etc/modprobe.conf
alias block-major-2-* floppy

strace -estat,open /sbin/modprobe -v floppy
open("/etc/", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/etc/", O_RDONLY) = 3
open("/lib/", O_RDONLY) = 3
open("/etc/modprobe.conf", O_RDONLY) = 3
open("/lib/modules/2.6.4/modules.dep", O_RDONLY) = 3
open("/proc/modules", O_RDONLY) = 3
open("/lib/modules/2.6.4/kernel/drivers/block/floppy.ko", O_RDONLY) = 3
insmod /lib/modules/2.6.4/kernel/drivers/block/floppy.ko

=> OK
without module floppy loaded:
mdir a:
Can't open /dev/fd0: No such device or address
No msg in KRB (dmesg) and log from /tmp/modprobe.log
modprobe -v floppy
insmod /lib/modules/2.6.4/kernel/drivers/block/floppy.ko
=> OK
mdir a:
=> OK

My questions are:
1. What process name has the "new" kmod? There´s no such process in the
2. What triggers to run the prog given in /proc/sys/kernel/modprobe (
for a missing device)?

Strange: Looks like there is no kmod build or loaded or ..
I should look in detail about this..

Kernel 2.6.4:
Some modules (floppy, lp, loop..) won´t be autoloaded any more since
2.4.21. There´s no block-major aso. request in the kernel-ring buffer.
I have /etc/modules.conf and /etc/modprobe.conf with modutils-2.4.21-23.1
and depmod -V: module-init-tools 3.0-pre5. How can I track this down?
Shouldn't be there a kmod process/ thread in the process list?

Check you have CONFIG_KMOD=y. If so, the correct way of debugging
module problems is something like this:

echo '#! /bin/sh' > /tmp/modprobe
echo 'echo "$@" >> /tmp/modprobe.log' >> /tmp/modprobe
echo 'exec /sbin/modprobe "$@"' >> /tmp/modprobe
chmod a+x /tmp/modprobe
echo /tmp/modprobe > /proc/sys/kernel/modprobe

Then do something that should cause the module to load: you'll see the
command which gets called in /tmp/modprobe.log. Then you can add "-v"
and run it manually, hopefully providing enlightenment.

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