Subject: Re: 2.6.24-rc3-mm1: I/O error, system hangs
From: James Bottomley <James.Bottomley@SteelEye.com>
To: Gabriel C <nix.or.die@googlemail.com>
Cc: Laurent Riffard <laurent.riffard@free.fr>, Hannes Reinecke <hare@suse.de>,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org
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References: <20071120204525.ff27ac98.akpm@linux-foundation.org>
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	 <4746814F.80502@free.fr> <4746866B.5070207@suse.de>
	 <4746BB9D.2030508@suse.de>  <4747135C.60205@free.fr>
	 <1195886569.3195.2.camel@localhost.localdomain> <47481FA6.9050506@free.fr>
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	 <47486569.1040406@googlemail.com>
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Date: Sat, 24 Nov 2007 20:04:06 +0200
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On Sat, 2007-11-24 at 18:54 +0100, Gabriel C wrote:
> James Bottomley wrote:
> > On Sat, 2007-11-24 at 13:57 +0100, Laurent Riffard wrote:
> >> Le 24.11.2007 07:42, James Bottomley a écrit :
> >>> On Fri, 2007-11-23 at 18:52 +0100, Laurent Riffard wrote:
> >>>> Le 23.11.2007 12:38, Hannes Reinecke a écrit :
> >>>>> Hannes Reinecke wrote:
> >>>>>> Laurent Riffard wrote:
> >>>>>>> Le 21.11.2007 23:41, Andrew Morton a écrit :
> >>>>>>>> On Wed, 21 Nov 2007 22:45:22 +0100
> >>>>>>>> Laurent Riffard <laurent.riffard@free.fr> wrote:
> >>>>>>>>
> >>>>>>>>> Le 21.11.2007 05:45, Andrew Morton a écrit :
> >>>>>>>>>> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24-rc3/2.6.24-rc3-mm1/
> >>>>>>>>> Hello, 
> >>>>>>>>>
> >>>>>>>>> My system hangs shortly after I logged in Gnome desktop. SysRq-W shows
> >>>>>>>>> that a bunch of task are blocked in "D" state, they seem to wait for
> >>>>>>>>> some I/O completion. I can try to hand-copy some data if requested.
> >>>>>>>>>
> >>>>>>>>> I found these messages in dmesg:
> >>>>>>>>>
> >>>>>>>>> ~$ grep -C2 end_request dmesg-2.6.24-rc3-mm1 
> >>>>>>>>> EXT3-fs: mounted filesystem with ordered data mode.
> >>>>>>>>> sd 0:0:0:0: [sda] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK
> >>>>>>>>> end_request: I/O error, dev sda, sector 16460
> >>>>>>>>> ReiserFS: sda7: found reiserfs format "3.6" with standard journal
> >>>>>>>>> ReiserFS: sda7: using ordered data mode
> >>>>>>>>> --
> >>>>>>>>> ReiserFS: sda7: Using r5 hash to sort names
> >>>>>>>>> sd 0:0:1:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK
> >>>>>>>>> end_request: I/O error, dev sdb, sector 19632
> >>>>>>>>> sd 0:0:1:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK,SUGGEST_OK
> >>>>>>>>> end_request: I/O error, dev sdb, sector 40037363
> >>>>>>>>> Adding 1048568k swap on /dev/mapper/vglinux1-lvswap.  Priority:-1 extents:1 across:1048568k
> >>>>>>>>> lp0: using parport0 (interrupt-driven).
> >>>>>>>>>
> >>>>>>>>> These errors occur *only* with 2.6.24-rc3-mm1, they are 100% reproducible.
> >>>>>>>>> 2.6.24-rc3 and 2.6.24-rc2-mm1 are fine.
> >>>>>>>>>
> >>>>>>>>> Maybe something is broken in pata_via driver ?
> >>>>>>>>>
> >>>>>>>> Could be - libata-reimplement-ata_acpi_cbl_80wire-using-ata_acpi_gtm_xfermask.patch
> >>>>>>>> and pata_amd-pata_via-de-couple-programming-of-pio-mwdma-and-udma-timings.patch
> >>>>>>>> touch pata_via.c.
> >>>>>>> None of the above...
> >>>>>>>
> >>>>>>> I did a bisection, it spotted git-scsi-misc.patch. 
> >>>>>>> I just run 2.6.24-rc3-mm1 + revert-git-scsi-misc.patch, and it works fine.
> >>>>>>>
> >>>>>>> I guess commit 8655a546c83fc43f0a73416bbd126d02de7ad6c0 "[SCSI] Do not 
> >>>>>>> requeue requests if REQ_FAILFAST is set" is the real culprit. The other 
> >>>>>>> commits are touching documentation or drivers I don't use. I'll try 
> >>>>>>> to revert only this one this evening.
> >>>> I can confirm : reverting commit 8655a546c83fc43f0a73416bbd126d02de7ad6c0 
> >>>> does fix the problem.
> >>>>
> >>>>>> Hmm. Weird. I'll have a look into it. Apparently I'll be returning an error where
> >>>>>> I shouldn't. Checking ...
> >>>>>>
> >>>>> Ok, found it. We are blocking even special commands (ie requests with PREEMPT not set)
> >>>>> when FAILFAST is set. Which is clearly wrong. The attached patch fixes this.
> >>>> Sorry, it's not enough. 2.6.24-rc3-mm1 + your patch still hangs with I/O errors.
> >>> I think the problem is the way we treat BLOCKED and QUIESCED (the latter
> >>> is the state that the domain validation uses and which we cannot kill
> >>> fastfail on).  It's definitely wrong to kill fastfail requests when the
> >>> state is QUIESCE.
> >>>
> >>> This patch (which is applied on top of Hannes original) separates the
> >>> BLOCK and QUIESCE states correctly ... does this fix the problem?
> >>
> >> No, it doesn't help... (2.6.24-rc3-mm1 + your patch still has problems)
> > 
> > OK, could you post dmesgs again, please.  I actually tested this with an
> > aic79xx card, and for me it does cause Domain Validation to succeed
> > again.
> > 
> 
> Are the patches indeed to fix that problem as well ? 
> 
> http://lkml.org/lkml/2007/11/23/5

That dmesg is from an unknown SCSI card exhibiting Domain Validation
problems, so it's a reasonable probability, yes ... but you'll need the
additional hack I just did to prevent further intermittent failures.

James


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