Re: [linux-usb-devel] Large USB storage devices cause df to hang and cpu load reaches 100%

[Kostas Peletidis]

Alan Stern wrote:

On Mon, 30 Jul 2007, Kostas Peletidis wrote:

Hi all,

I would like to report a problem I have noticed since linux-2.6.22 that most likely has to do with the USB subsystem. I have tried both kernel versions 2.6.22 and 2.6.22.1(configured with make oldconfig) and in both cases whenever I plug in a fairly large(500GB) MyBook usb2 hard disk df stops producing output and hangs for about a minute when it reaches the usb disk. Interestingly enough the disk's directory tree can be accessed immediately. It is only df and Thunar, the xfce window manager, that slow down. During this temporary hang the cpu load fluctuates and reaches 100% several times. When I plugged in a small(512MB) usb2 memory stick, instead of the disk, df paused only momentarily before terminating normally. This suggests to me that the size of the device affects the duration of the delay. The modules I use, apart from usb_storage, are ehci_hcd and uhci_hcd. With linux-2.6.21.5 both usb devices work fine. I don't know how to proceed from here. Please let me know if you need additional information or if I need to contact someone else. Thank you.

Alan Stern

Turn on CONFIG_USB_DEBUG and then check the output from dmesg after running the df program. If it shows something peculiar then you should try using usbmon. Instructions are in the kernel source file Documentation/usb/usbmon.txt. If all else fails, you can install Git and use bisection on the set of kernel versions between 2.6.21 and 2.6.22, to find which patch caused the odd behavior to start.

Hi Alan,



Jul 31 21:05:28 dragon kernel: [ 915.850000] usb 1-3.2: usb_probe_device

Jul 31 21:05:28 dragon kernel: [ 915.851000] usb 1-3.2:1.0: uevent
Jul 31 21:05:28 dragon kernel: [ 915.851000] usb 1-3.2:1.0: uevent

Jul 31 21:05:28 dragon kernel: [ 915.852000] usb-storage: device found at 8

Jul 31 21:05:33 dragon kernel: [ 920.860000] sda: sda1






Regards,
Kostas

I enabled CONFIG_USB_DEBUG and reproduced the problem but didn't see any messages in the dmesg output. To ensure that the debug code was indeed built in I unplugged the disk then plugged it back in. I got quite a few messages, here are the last of them: Jul 31 21:05:28 dragon kernel: [ 915.850000] usb 1-3.2: configuration #1 chosen from 1 choice Jul 31 21:05:28 dragon kernel: [ 915.851000] usb 1-3.2: adding 1-3.2:1.0 (config #1, interface 0) Jul 31 21:05:28 dragon kernel: [ 915.851000] usb-storage 1-3.2:1.0: usb_probe_interface Jul 31 21:05:28 dragon kernel: [ 915.851000] usb-storage 1-3.2:1.0: usb_probe_interface - got id Jul 31 21:05:28 dragon kernel: [ 915.852000] scsi1 : SCSI emulation for USB Mass Storage devices Jul 31 21:05:28 dragon kernel: [ 915.852000] usb-storage: waiting for device to settle before scanning Jul 31 21:05:28 dragon kernel: [ 915.853000] drivers/usb/core/inode.c: creating file '008' Jul 31 21:05:33 dragon kernel: [ 920.853000] scsi 1:0:0:0: Direct-Access WD 5000AAKS Externa 101a PQ: 0 ANSI: 4 Jul 31 21:05:33 dragon kernel: [ 920.856000] sd 1:0:0:0: [sda] 976773168 512-byte hardware sectors (500108 MB) Jul 31 21:05:33 dragon kernel: [ 920.856000] sd 1:0:0:0: [sda] Write Protect is off Jul 31 21:05:33 dragon kernel: [ 920.856000] sd 1:0:0:0: [sda] Mode Sense: 11 00 00 00 Jul 31 21:05:33 dragon kernel: [ 920.856000] sd 1:0:0:0: [sda] Assuming drive cache: write through Jul 31 21:05:33 dragon kernel: [ 920.859000] sd 1:0:0:0: [sda] 976773168 512-byte hardware sectors (500108 MB) Jul 31 21:05:33 dragon kernel: [ 920.860000] sd 1:0:0:0: [sda] Write Protect is off Jul 31 21:05:33 dragon kernel: [ 920.860000] sd 1:0:0:0: [sda] Mode Sense: 11 00 00 00 Jul 31 21:05:33 dragon kernel: [ 920.860000] sd 1:0:0:0: [sda] Assuming drive cache: write through Jul 31 21:05:33 dragon kernel: [ 920.863000] sd 1:0:0:0: [sda] Attached SCSI disk Jul 31 21:05:33 dragon kernel: [ 920.863000] sd 1:0:0:0: Attached scsi generic sg0 type 0 Jul 31 21:05:33 dragon kernel: [ 920.866000] usb-storage: device scan complete I see most of these messages at boot time even with older 2.6 kernels. The problem appears after the "device scan complete" message is traced. The patch that caused this issue was added between the 2.6.21.5 and 2.6.22 releases. The only patch that led to 2.6.21.6 had to do with nf_conntrack_h323 so this leaves us with the patches between 2.6.21.6 and 2.6.22. There are quite a few usb changes in that changelog so I was hoping that someone might recognise/remember something relevant.

config-2.6.22.1_usbdebug.bz2
Description: application/bzip

-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems?  Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >>  http://get.splunk.com/
_______________________________________________
linux-usb-devel@lists.sourceforge.net
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel