Re: BAD_SG_DMA panic in aha1542

From: Bob Tracy
Date: Fri Apr 27 2007 - 19:53:39 EST

James Bottomley wrote:
> On Fri, 2007-04-27 at 16:47 -0500, Bob Tracy wrote:
> > I previously reported an ISA DMA issue for the 2.6.12 kernel. The issue
> > persists through at least 2.6.18. SCSI controller is an Adaptec
> > AHA-1542B (ISA).
> >
> > The action "mount -t iso9660 /dev/scd0 /mnt/cdrom -r"
> >
> > produces
> >
> > (cdrom detection messages as various modules autoload, then...)
> Knowing what these messages are is would be helpful; it tells me what
> point in the initialisation it got to.

Sorry about that... I'm running the DSL-N distribution (based on
Knoppix), and having to transcribe the log messages by hand from the
console, i.e., there's no logfile to cut-and-paste from :-(. I don't
have access to the machine except on weekdays, but I'll repeat the
crash first thing Monday morning and copy everything that's there...

> I'm interested.
> This is clearly a use_sg==1 path that has failed to bounce the buffer
> for some reason ... and I was contemplating eliminating the GFP_DMA from
> our sr driver because I thought the block bouncing had it covered.
> It might also be helpful to apply this patch. It should give a stack
> trace of the problem command and not immediately panic the box.

I'll throw together a 2.6.21 kernel with this patch and give it a try.
Again, it will be at least Monday before you hear back from me on this.


Bob Tracy WTO + WIPO = DMCA?
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