Re: 2.6.32-rc4ish: task umount blocked for more than 120 secondsafter USB drive removal

From: Jens Axboe
Date: Wed Nov 04 2009 - 02:41:43 EST

On Tue, Nov 03 2009, Andrew Morton wrote:
> On Tue, 20 Oct 2009 23:26:17 -0600
> Robert Hancock <hancockrwd@xxxxxxxxx> wrote:
> > Running a post-2.6.32-rc4 git kernel, and just unmounted a USB drive
> > after writing a bunch of data to it, then pulled the plug after I
> > thought it had finished unmounting, but apparently it hadn't.. Ran into
> > a hung task warning that repeats every 120 seconds, the umount command
> > for the drive is stuck in D state.
> >
> > The full SysRq-T output is shown at the bottom.. any ideas what it's
> > waiting for?
> At a guess I'd say the new per-bdi writeback stuff blew up. Is this
> still happening in current mainline?

It happens in -rc6, it should be fixed in current -git. Robert, can you
try and confirm?

> It's remarkable how much harder these traces are to read post-wordwrapping.

Indeed, I always copy into a new buffer and un-wrap them :/

Jens Axboe

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at