Date: Fri, 27 Jan 2006 21:00:54 +0100
From: Jens Axboe <axboe@suse.de>
To: Chase Venters <chase.venters@clientec.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>,
       James Bottomley <James.Bottomley@SteelEye.com>,
       Neil Brown <neilb@suse.de>, linux-kernel@vger.kernel.org,
       linux-scsi@vger.kernel.org, akpm@osdl.org, a.titov@host.bg,
       askernel2615@dsgml.com, jamie@audible.transient.net
Subject: Re: More information on scsi_cmd_cache leak... (bisect)
Message-ID: <20060127200054.GD9068@suse.de>
References: <200601270410.06762.chase.venters@clientec.com> <17369.65530.747867.844964@cse.unsw.edu.au> <20060127112352.GF4311@suse.de> <20060127112837.GG4311@suse.de> <43DA6F33.3070101@cs.wisc.edu> <1138389616.3293.13.camel@mulgrave> <43DA787F.4080406@cs.wisc.edu> <20060127194927.GB9068@suse.de> <Pine.LNX.4.64.0601271351070.9232@turbotaz.ourhouse>
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On Fri, Jan 27 2006, Chase Venters wrote:
> On Fri, 27 Jan 2006, Jens Axboe wrote:
> 
> >On Fri, Jan 27 2006, Mike Christie wrote:
> >>James Bottomley wrote:
> >>>On Fri, 2006-01-27 at 13:06 -0600, Mike Christie wrote:
> >>>
> >>>>It does not have anything to do with this in scsi_io_completion does it?
> >>>>
> >>>>       if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
> >>>>               return;
> >>>>
> >>>>For that case the scsi_cmnd does not get freed. Does it come back around
> >>>>again and get released from a different path?
> >>>
> >>>
> >>>It looks such a likely candidate, doesn't it.  Unfortunately, Tejun Heo
> >>>removed that code around 6 Jan (in [BLOCK] update SCSI to use new
> >>>blk_ordered for barriers), so if it is that, then the latest kernels
> >>>should now not be leaking.
> >>>
> >>
> >>Oh, I thought the reports were for 2.6.15 and below which has that
> >>scsi_io_completion test. Have there been reports for this with
> >>2.6.16-rc1 too?
> >
> >The reports of leaks are only with > 2.6.15, not with 2.6.15.
> >
> 
> Correction... my leak is with 2.6.15. I discovered it originally in an 
> NVIDIA-tainted, sk98lin-patched 2.6.15, but my bisect was stock 2.6.15 
> (bad) to 2.6.14 (good) in Linus's tree, sans any tainting or 
> modifications.
> 
> I haven't actually tried building the latest Linus kernel from git. I'll 
> do a pull and give it a try when I get home.

Ah, so the raid barrier stuff predates 2.6.15, I didn't think it did.
Can you try 2.6.16-rc1 at least? If this is the blk_complete_barrier()
leak, then it's not so interesting.

As a work around, please try (in 2.6.15) to set ordered_flush to 0 in
the scsi host template for your sata driver.

-- 
Jens Axboe

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