Re: Hanging ext3 or USB, linux 2.6.16-rc6-mm2

[Jan Kara <jack@suse.cz>]

> I managed to hang ext3 or usb today.
> I have a small machine that boot off a compactflash card.
> I want to use a bigger card, so I used scp to copy everything
> from that machine to a new 4GB card in a usb cardreader.
> This cardreader have never given me trouble before, but is
> usually used for reading.
> 
> I decided on a ext3 fs in order to avoid long fsck runs,
> and a minimal 4MB journal in order to not waste space.
> Disk seeks are supposed to be really cheap on a device
> with no moving parts anyway.  The root reserved percentage
> is 1% instead of the usual 5% - more space, and fragmentation
> will probably not hurt much with cheap seeks.
> 
> When scp had filled the card to 71% of capacity (according to df), 
> it stopped in the middle of a file.  I first suspected network
> errors, but a "ls /mnt" hung.
> 
> I now have the following processes in D-state:
> [khubd] [scsi_eh_4] [usb-storage] [kjournald] scp,
> 3 x [pdflush], 2 x ls, lsusb, and a sync.
> 
> Could this be a ext3 problem due to the small journal or something?
> 
> Or is a usb problem more likely? "Dmesg" shows an
> usb disconnect sometime after I mounted that filesystem,
> but it seems to be usblp0 which looks like the printer to me.
  I'd guess it is some USB/block layer problem. If just ext3 hung, then
you would not see [usb-storage] and similar hung. I would need to see
where each process hung to tell more..

								Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs