Errors in dmesg - Test WP failed, assume Write Enabled

Question

I'm experiencing some problems with drive cache and I don't know what's causing these problems. This is my dmesg:

[11690.011238] sd 6:0:0:0: [sdb] Asking for cache data failed
[11690.011248] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11741.720851] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
[11741.722965] sd 6:0:0:0: [sdb] Asking for cache data failed
[11741.722975] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11793.433011] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
[11793.435347] sd 6:0:0:0: [sdb] Asking for cache data failed
[11793.435356] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11845.140846] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
[11845.143098] sd 6:0:0:0: [sdb] Asking for cache data failed
[11845.143102] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[11896.856723] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled

There are hundreds of these lines. It is happening since I've installed Ubuntu 12.04 64bit beta2 from my pendrive. Now I don't have anything at /dev/sdb. I don't know if these errors are making my system less responsive, but I think that dmesg shouldn't look like this.

My kernel version: 3.2.0-24-generic.

Do you have any idea how to solve it?

Thank you in advance.

Solution 1

I'm having the same issue on the official 12.04 LTS relase i also believe it is causing the system to be less responsive. According to some sources it's harmless. (i can apparently only post 2 links)

The following thinks this is error output from an onboard card reader:

https://bbs.archlinux.org/viewtopic.php?pid=1059099

It's confirmed to be an upstream issue in

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/987993

Run lsusb and find the offending device

nathan@Ham-Bone:~$ lsusb 

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 002: ID 0bda:0158 Realtek Semiconductor Corp. USB 2.0 multicard reader

In my case it's the Realtek multicard reader which a quick check of

$ dmesg | grep realtek
[    4.716068] usbcore: registered new interface driver ums-realtek
$ lsmod | grep realtek
ums_realtek            17920  0 

reveals a module ums-realtek

$sudo rmmod ums_realtek

Fixes the problem in a reversible way for me. That is

$sudo modprobe ums_realtek

enables the card reader again. I haven't tested if it works since I never use it.

If this doesn't work there are some other ways to disable usb devices by unbinding them in the /sys/ directory.

Solution 2

I found that loading the driver with option ss_en=0 works. Doing

echo "ums-realtek ss_en=0" |sudo tee -a /etc/modules

makes the change permanent.

Further explanation:

While trying to discover why this message happens, I looked into the options for the two modules involved, ums-realtek and usb-storage. I did not feel that loading and unloading the ums-realtek module every time was a suitable solution, as I am often using the card reader.

Checking module options:

# modinfo ums-realtek 
  parm: auto_delink_en  enable auto delink (int)
  parm: ss_en           enable selective suspend (int)
  parm: ss_delay        seconds to delay before entering selective suspend (int)

Research into what these options were for did not yield any result, and I did not feel inclined to bother the author by email. Since this driver uses the usb-storage as well, I felt the "suspend" option might be enabled by default ( perhaps to conserve battery on laptops ) and the messages a result of wakeup-query-suspend sequences. Since I didn't care if the device was constantly powered on or not, I tried setting this option to 0 (off) and it works.

Comments

[Admin]

awesome, I did have a microsSD card reader on my laptop. I had the adapter in but not SD card installed and as soon as I removed the adapter the errors stopped awsomeer.... :) I hate seeing errors in my logfiles, like to have everything running as 100% as I possibly can, thanks thanks thanks :)

[Valeriy Kovtoen]

I should add you can also blacklist the module if you never use it

[mescam]

It seems like we have the same device that is causing the problem. Bus 001 Device 003: ID 0bda:0158 Realtek Semiconductor Corp. USB 2.0 multicard reader Hope they will solve it soon. Thanks

[mescam]

Gedit is installed on desktop ubuntu by default, so packages on which it depends should be present too.

[Valeriy Kovtoen]

It appears that a recent kernel update has fixed the problem. :)

[Mark]

FYI: this same workaround is mentioned in a bug-report about this issue: bugs.launchpad.net/ubuntu/+source/linux/+bug/925760/comments‌​/75