linux-kernel - RE: kernel BUG at drivers/block/cciss.c:1260! (with recent linux-2.6 tree)

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Date:	Tue, 29 Jan 2008 19:03:41 +0000
From:	"Miller, Mike (OS Dev)" <Mike.Miller@...com>
To:	Jens Axboe <jens.axboe@...cle.com>,
	Andrew Vasquez <andrew.vasquez@...gic.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"k-ueda@...jp.nec.com" <k-ueda@...jp.nec.com>,
	"j-nomura@...jp.nec.com" <j-nomura@...jp.nec.com>
Subject: RE: kernel BUG at drivers/block/cciss.c:1260! (with recent
  linux-2.6  tree)

Jens wrote:

> -----Original Message-----
> From: Jens Axboe [mailto:jens.axboe@...cle.com]
> Sent: Tuesday, January 29, 2008 12:54 PM
> To: Andrew Vasquez
> Cc: Linux Kernel Mailing List; Miller, Mike (OS Dev);
> k-ueda@...jp.nec.com; j-nomura@...jp.nec.com
> Subject: Re: kernel BUG at drivers/block/cciss.c:1260! (with
> recent linux-2.6 tree)
>
> On Tue, Jan 29 2008, Andrew Vasquez wrote:
> > On Tue, 29 Jan 2008, Jens Axboe wrote:
> >
> > > On Tue, Jan 29 2008, Andrew Vasquez wrote:
> > > > On Tue, 29 Jan 2008, Jens Axboe wrote:
> > > >
> > > > > > Here the final snippet that was logged:
> > > > > >
> > > > > > [   12.724997] input: USB HID v1.01 Mouse [HP
> Virtual Keyboard] on usb-0000:01:04.4-1
> > > > > > [   12.728971] usbcore: registered new interface
> driver usbhid
> > > > > > [   12.732866] drivers/hid/usbhid/hid-core.c:
> v2.6:USB HID core driver
> > > > > > [   12.741172] TCP cubic registered
> > > > > > [   12.744506] NET: Registered protocol family 1
> > > > > > [   12.744884] NET: Registered protocol family 17
> > > > > > [   12.749217] Freeing unused kernel memory: 228k freed
> > > > > > [   12.885823] cciss rq: dev cciss/c0d0: type=2, flags=104c8
> > > > > > [   12.888929]
> > > > > > [   12.888930] sector 6510615555426900570, nr/cnr 0/0
> > > > > > [   12.892895] bio ffff81042f130730, biotail
> ffff81042f130730, buffer 0000000000000000, data
> 0000000000000000, len 0
> > > > > > [   12.896895] cdb: 12 00 00 00 fe 00 00 00 00 00
> 00 00 00 00 00 00
> > > > >
> > > > > Ah ok, I see the problem... cciss is overriding the
> data_len for
> > > > > BLOCK_PC requests, hence it does not complete them properly.
> > > > > Hmm. Does this work?
> > > > >
> > > > > diff --git a/drivers/block/cciss.c
> b/drivers/block/cciss.c index
> > > > > ef50068..b6fa52e 100644
> > > > > --- a/drivers/block/cciss.c
> > > > > +++ b/drivers/block/cciss.c
> > > > > @@ -2524,7 +2524,6 @@ after_error_processing:
> > > > >                 resend_cciss_cmd(h, cmd);
> > > > >                 return;
> > > > >         }
> > > > > -       cmd->rq->data_len = 0;
> > > > >         cmd->rq->completion_data = cmd;
> > > > >         blk_complete_request(cmd->rq);  }
> > > >
> > > >
> > > > Things look good so far -- with the patch above I can
> finally boot
> > > > the machine.
> > >
> > > Cool, sorry about that. Will get that applied asap. So after this
> > > patch was applied, you didn't see any debug messages from
> > > blk_dump_rq_flags() anymore, right?
> >
> > That's correct.  I've yet to see any additional debug-messages from
> > blk_dump_rq_flags().
>
> Great, thanks for confirming. It does look like a clear bug
> in cciss, it just got exposed now that it uses proper end
> request handling. We never need to clear ->data_len, since
> for blk_fs_request() it will be cleared on init. So just
> setting a residual count there for blk_fs_request() like
> cciss does is fine.

Just so I'm clear: just removing the one line is enough to resolve the problem?

-- mikem


>
> Anyway, it's in my pending queue for Linus.
>
> --
> Jens Axboe
>
>
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