Re: SATA exceptions with 2.6.20-rc5

[Jeff Garzik <jeff@garzik.org>]

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..

It's possible the flush-cache command takes longer than 30 seconds, if 
the cache is large, contents are discontiguous, etc.  It's a 
pathological case, but possible.

Or maybe flush-cache doesn't get a 30 second timeout, and it should...? 
  (thinking out loud)

	Jeff