lkml.org 
[lkml]   [2008]   [Oct]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Timeout regression introduced by 242f9dcb8ba6f68fcd217a119a7648a4f69290e9
Mike Anderson wrote:
> Tejun Heo <tj@kernel.org> wrote:
>> James Bottomley wrote:
>>> On Sun, 2008-10-26 at 18:46 +0900, Tejun Heo wrote:
>>>> Hello, Jens.
>>>>
>>>> Commit 242f9dcb8ba6f68fcd217a119a7648a4f69290e9 introduces a strange
>>>> regression for libata. The second timeout gives puts different
>>>> pointer from the issued command onto eh_cmd_q breaking libata EH
>>>> command matching which triggers WARN_ON() in ata_eh_finish() and hangs
>>>> command processing or causes oops later depending on circumstances.
>>>>
>>>> Here are logs with induced timeouts (patch attached). In commit
>>>> 242f9dcb8, the XXX messages for the second timeout shows different
>>>> scsi_cmd pointers for eh_cmd_q and qc->scmd which is initialized by
>>>> ata_scsi_qc_new() during command translation.
>>> I can't see a way we could be getting a different command passed in from
>>> the actual one, since the only way to lose the command from the request
>>> is to go through the command completion routines which free it (and end
>>> the request).
>> I have no idea either. It's something in the timeout logic because on
>> the issue path the scmd pointer is identical but on tiemout pointer
>> for another scmd is queued on eh_cmd_q, which doesn't make much sense.
>>
>
> I was trying to recreate this error using ata_ram wth v2.6.28-rc2.
> Currently I am not able to see this error on timeout recovery using this
> setup. Does IO load (or other factors) effect the error being seen?

Not at all. That's the only write command I issued.

--
tejun


\
 
 \ /
  Last update: 2008-10-28 02:15    [W:0.051 / U:0.400 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site