Comment 54 for bug 548546

The patch to fix the issue currently is queued in linux-next:

commit 23e2632cc815fb6cc38560805a12be586e23a8f1
Author: Phillip Susi <email address hidden>
Date: Sat Jul 16 23:31:06 2011 +1000

    Fix the loopback device to emit a uevent on auto release. The loopback
    driver failed to emit the change uevent when auto releasing the device.
    Fix lo_release() to pass the bdev to loop_clr_fd() so it can emit the
    event.

    Cc: Jens Axboe <email address hidden>
    Signed-off-by: Phillip Susi <email address hidden>
    Signed-off-by: Andrew Morton <email address hidden>

As the merge window has opened, it should likely get into 3.1 from where we could pick it. I am no sure Ayan's patch would make it (sure one could try to send it upstream (after removing the unnecessary whiespace change)) upstream. From the lo_ioctl side bdev is the known (passed in argument) while lo is not. Theoretically clear could be called before set and that may or may not be checked for under all circumstances.