Naughty ramdrives

From: Alexey Dobriyan
Date: Thu Sep 07 2006 - 16:59:53 EST


You'd laugh, but...

Summary:

After loading and unloading rd.ko many times "ls -l /dev/ram*"
results are not persistent.

Steps to reproduce:

# while true; do modprobe rd && rmmod rd; done
[wait ~10 seconds]
^C
# modprobe rd

# ls -l /dev/ram*
lrwxrwxrwx 1 root root 5 Sep 8 00:35 /dev/ram12 -> rd/12
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram6 -> rd/6
# ls -l /dev/ram*
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram0 -> rd/0
lrwxrwxrwx 1 root root 5 Sep 8 00:35 /dev/ram13 -> rd/13
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram6 -> rd/6
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram7 -> rd/7
# ls -l /dev/ram*
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram0 -> rd/0
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram1 -> rd/1
lrwxrwxrwx 1 root root 5 Sep 8 00:35 /dev/ram11 -> rd/11
lrwxrwxrwx 1 root root 5 Sep 8 00:35 /dev/ram12 -> rd/12
lrwxrwxrwx 1 root root 5 Sep 8 00:35 /dev/ram14 -> rd/14
lrwxrwxrwx 1 root root 5 Sep 8 00:35 /dev/ram15 -> rd/15
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram3 -> rd/3
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram7 -> rd/7
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram8 -> rd/8
lrwxrwxrwx 1 root root 4 Sep 8 00:35 /dev/ram9 -> rd/9

Versions:

Linux 2.6.18-rc5
udev 087

P.S.:

This was noticed while investigating #4899
http://bugme.osdl.org/show_bug.cgi?id=4899
where /dev/ram0 when opened, pins module indefinitely. It seems that
adding ->release() which undoes

inode = igrab(bdev->bd_inode);

should do the trick. Am I right?

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