Re: SATA exceptions with 2.6.20-rc5

[Björn Steinbrink <B.Steinbrink@gmx.de>]

On 2007.01.15 22:17:24 +0100, Björn Steinbrink wrote:
> On 2007.01.14 17:43:53 -0600, Robert Hancock wrote:
> > Björn Steinbrink wrote:
> > >Hi,
> > >
> > >with 2.6.20-rc{2,4,5} (no other tested yet) I see SATA exceptions quite
> > >often, with 2.6.19 there are no such exceptions. dmesg and lspci -v
> > >output follows. In the meantime, I'll start bisecting.
> > 
> > ...
> > 
> > >ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
> > >ata1.00: cmd e7/00:00:00:00:00/00:00:00:00:00/a0 tag 0 cdb 0x0 data 0 in
> > >         res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
> > >ata1: soft resetting port
> > >ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
> > >ata1.00: configured for UDMA/133
> > >ata1: EH complete
> > >SCSI device sda: 160086528 512-byte hdwr sectors (81964 MB)
> > >sda: Write Protect is off
> > >sda: Mode Sense: 00 3a 00 00
> > >SCSI device sda: write cache: enabled, read cache: enabled, doesn't 
> > >support DPO or FUA
> > 
> > Looks like all of these errors are from a FLUSH CACHE command and the 
> > drive is indicating that it is no longer busy, so presumably done. 
> > That's not a DMA-mapped command, so it wouldn't go through the ADMA 
> > machinery and I wouldn't have expected this to be handled any 
> > differently from before. Curious..
> 
> My latest bisection attempt actually led to your sata_nv ADMA commit. [1]
> I've now backed out that patch from 2.6.20-rc5 and have my stress test
> running for 20 minutes now ("record" for a bad kernel surviving that
> test is about 40 minutes IIRC). I'll keep it running for at least 2 more
> hours.

Yep, that one seems to be guilty. 2.6.20-rc5 with that commit backed out
survived about 3 hours of testing, while the average was around 5
minutes for a failure, sometimes even before I could log in.
I took a look at the patch, but I can't really tell anything.
nv_adma_check_atapi_dma somehow looks like it should not negate its
return value, so that it returns 0 (atapi dma available) when
adma_enable was 1. But I'm not exactly confident about that either ;)
Will it hurt if I try to remove the negation?

Thanks,
Björn
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