[Bug 25832] kernel crashes upon resume if usb devices are removed when suspended

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https://bugzilla.kernel.org/show_bug.cgi?id=25832





--- Comment #61 from rocko <rockorequin@hotmail.com>  2011-04-22 10:37:37 ---
I can reliably reproduce it with the following, running in Ubuntu (11.04 at the
moment, but 10.10 works as well):

1. I insert a USB key formatted with ext4.

2. I run this simple script, passing the id that shows up in
/sys/bus/usb/drivers/usb-storage for the USB key as the argument, eg 2-2:1.0:

#!/bin/bash
SLEEP=3
function list {
  if [ -e "$1" ]; then
    echo $1
  fi
}

cd /sys/bus/usb/drivers/usb-storage
if [ "$1" == "" ] || [ "$2" != "" ]; then
  echo "Usage: $0 usb device"
  echo "With one of these: "
  for file in 1* ; do list $file; done
  for file in 2* ; do list $file; done
  exit 1
fi

echo 8 > /proc/sys/kernel/printk
count=1
while true; do
  echo -n $1 >unbind
  echo $count
  sleep $SLEEP
  echo -n $1 >bind
  sleep $SLEEP
  ((count=count+1))
done



I'm making it sleep 3 seconds between unbind/bind events because that gives
Ubuntu plenty of time to mount the drive after the bind.

When it oopses, it typically oopses within a few seconds of the unbind event
(I'd say in less than 10 seconds and often immediately). For me it normally
will oops inside 10 bind/unbinds, but 2.6.39-rc4 took more like 20 to 30 goes
when I tried it this morning).

I'll try again sending the output to another PC, but I'm pretty sure last time
I tried that the ssh session crashed before it could dump the stack trace, just
as the tty console usually crashes before it finishes dumping.

When I get time I'll try some variations as well like making it sync and sleep
before the unbind.

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