Re: memory leak in scsi_cmd_cache 2.6.15

[Pasi Kärkkäinen <pasik@iki.fi>]

On Sun, Jan 29, 2006 at 10:38:12AM -0600, James Bottomley wrote:
> On Sun, 2006-01-29 at 17:50 +0200, Pasi Kärkkäinen wrote:
> > Are all sata drivers affected by this bug in 2.6.15?
> 
> Well, all SCSI drivers are affected by it, yes.  However, SATA devices
> are peculiarly affected because the ordered_flush method of enforcing
> barriers, which is where the leak is, can only be implemented for
> devices that don't do tag command queueing (i.e. don't have multiple
> commands outstanding for a given single device).  By and large, SATA
> drivers are the only drivers in the SCSI subsystem that can't do tag
> command queueing, which is why the problem didn't show up for any other
> type of SCSI driver.
>

OK.. thanks for summarizing this.
 
> > Any 'official' patch available?
> 
> Well, yes, 2.6.16-rc1 has this fixed.  I can't see backporting this to
> 2.6.15.x since it represents a significant functionality enhancement as
> well, so I'd lean towards just forcing ordered_flush to zero in 2.6.15.x
> which seems to be the best bug fix.
>

OK.
 
> > Or is the recommended workaround to set ordered_flush to 0 to fix this..
> > does that have any downsides?
> 
> setting ordered_flush to zero for 2.6.15 turns off the flushing
> functionality and restores the old behaviour.  I don't see that there
> would be any down side to this.
> 

That's good to hear. Thanks.

-- Pasi 
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