Re: [linux-usb-devel] khubd and ent:sda1 sucking CPU with reiser4+ USB HD

From: Alan Stern
Date: Wed Mar 07 2007 - 15:22:47 EST


On Wed, 7 Mar 2007, Eric Buddington,,, wrote:

> > > So SysRq-t doesn't show anything about khubd, and SysRq-p doesn't give
> > > me anything at all. What else can I try?

How about SysRq-r?

> > I'm baffled. khubd should have shown up as the process with ID 163. Is
> > that process listed under a different name?
>
> It does show up under /proc/163, for whatever that's worth.

Maybe that means the process is dying but isn't completely dead yet, and
it's stuck running something inside the reiser4 driver. Unless we can
find out what it is, though, there isn't much we can do.

> Going through the list of processes dumped by SysRq-t, here are the
> ones I didn't knowingly start myself:
>
> aio/0
> ata/0
> ata_aux
> ent:md1.
> events/0
> ib_addr
> ib_cm/0
> ib_mcast
> iw_cm_wq
> kacpid
> kblockd/0
> kcryptd/0
> khelper
> khpsbpkt
> kmirrord
> kmpathd/0
> kprefetchd
> kpsmoused
> kseriod
> ksnapd
> ksuspend_usbd
> kswapd0
> kthread
> ktxnmgrd:md1:
> ktxnmgrd:sda1
> md2_raid1
> pdflush
> rdma_cm
> reiserfs/0
> scsi_eh_0
> watchdog/0

Most of those (maybe all of them) are built-in kernel threads.

> And khubd is still showing up as a major CPU consumer. Interestingly,
> ent:sda1! is also absent from the SysRq-t listing, though present (and
> using lost of CPU) according to 'top' (ps, oddly, hangs in 'D' state
> after listing some processes).

Something is badly messed up somewhere, but I have no idea what it could
be.

These problems start with some USB resets, right? Did they occur with
earlier kernel versions, or is this new behavior?

How often does the problem occur?

Alan Stern

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