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Date: Fri, 5 Sep 2008 11:28:38 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: "Miller, Mike (OS Dev)" <Mike.Miller@hp.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>,
       James Bottomley <James.Bottomley@hansenpartnership.com>,
       lkml <linux-kernel@vger.kernel.org>, scsi <linux-scsi@vger.kernel.org>,
       akpm <akpm@linux-foundation.org>
Subject: Re: in 2.6.23-rc3-git7 in do_cciss_intr
Message-ID: <20080905092838.GS20055@kernel.dk>
References: <20080821091514.8f56e2d5.randy.dunlap@oracle.com> <0F5B06BAB751E047AB5C87D1F77A778835118100D6@GVW0547EXC.americas.hpqcorp.net> <20080821172653.3e3e855c.randy.dunlap@oracle.com> <0F5B06BAB751E047AB5C87D1F77A77883511810706@GVW0547EXC.americas.hpqcorp.net> <1219420487.3339.22.camel@localhost.localdomain> <48AEEE0A.1010900@oracle.com> <1219424538.3339.51.camel@localhost.localdomain> <0F5B06BAB751E047AB5C87D1F77A77883511810894@GVW0547EXC.americas.hpqcorp.net> <48C013D9.7060309@oracle.com> <0F5B06BAB751E047AB5C87D1F77A7788413663D229@GVW0547EXC.americas.hpqcorp.net>
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On Thu, Sep 04 2008, Miller, Mike (OS Dev) wrote:
> > >>> 0x3bb2 <do_cciss_intr+1649>:    mov    0x2(%r8),%dx
> > >>> 0x3bb7 <do_cciss_intr+1654>:    test   %dx,%dx
> > >>> 0x3bba <do_cciss_intr+1657>:    je     0x3f0e <do_cciss_intr+2509>
> > >>>
> > >>>
> > >>> $ addr2line -e cciss.o -f  do_cciss_intr+0x627 SA5_fifo_full
> > >>>
> > /home/rdunlap/linsrc/linux-2.6.27-rc3-git7/drivers/block/cciss.h:206
> > >> OK ...that's confusing.  It seems to be saying that ctrlr_info_t *
> > >> was NULL.  However, I can't see a way of getting into the
> > fifo_full
> > >> callback from do_cciss_intr ..
> > >> especially not with an NULL host.
> > >>
> > >> James
> > >
> > > That is weird. Even if we could get there fifo_full doesn't
> > do anything but wait for a bit.
> >
> > Hi,
> >
> > This just happened again.  This time it's on 2.6.27-rc5-git3.
> >
> > ~Randy
> 
> Thanks Randy. I think. :)
> 
> I'll try to recreate in my lab.

This looks somewhat strange, mostly like 'c' is NULL and it's oopsing in
in removeQ (I don't think Randy's analysis is correct in assuming it's
'h' and it's in fifo_full). Given that 'c' cannot be NULL, it's c->prev
or c->next that are NULL.

-- 
Jens Axboe