On Mon, Sep 15, 2014 at 6:41 AM, Jacobo Pantoja <jacobopantoja@xxxxxxxxx> wrote:
> Dears,
>
> Thank you for taking your time to answer. See my comments below.
>
> On 14 September 2014 22:03, Robert Hancock <hancockrwd@xxxxxxxxx> wrote:
>> On Sun, Sep 14, 2014 at 3:37 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
>>>
>>> (cc'ing Robert Hancock)
>>>
>>> Hello,
>>>
>>> On Sat, Sep 13, 2014 at 11:50:08PM +0200, Jacobo Pantoja wrote:
>>> > (Sorry if you receive twice, I have noticed that the first email had
>>> > blank subject)
>>> > Dear Tejun Heo and linux-ide team,
>>> >
>>> > I'm Jacobo Pantoja. I'm a technology passionate and electronics
>>> > engineer.
>>> > I have my ("beloved") computer with an nForce4 chipset, and I have had
>>> > almost
>>> > always the ADMA interface enabled. The board itself is ASUS A8N-E, with
>>> > reportedly CK804 chipset, if it may be relevant at all.
>>> >
>>> > As suggested by Tejun, I'm sending my problem to the list.
>>> >
>>> > I noticed that from time to time the machine was freezed, but I was not
>>> > able to correctly catch the trigger. Till yesterday.
>>> >
>>> > I noticed that one of my 2 TB drives had some few sectors, which were
>>> > marked as "pending reallocation", but not reallocated. When this has
>>> > happened to me (in different computers, though), I solved it by dd'ing
>>> > the whole disk, locating the bad sector(s) and filling it with zeroes.
>>> > So I tried... and I have discovered that when a bad sector is tried to
>>> > be read, the system locks up.
>>> >
>>> > You may find attached:
>>> > * dmesg when adma activated (but not including the moment of the error
>>> > because the computer freezes)
>>> > * photo taken in the moment of the error with adma activated
>>> > * dmesg when adma is not activated, including the moment of the error
>>> >
>>> > This is totally reproducible**, and I am willing to do any additional
>>> > testing that may help in solving this issue, if there is any interest.
>>> >
>>> > **I have noticed, while trying to provide clear dmesg's and so on, that
>>> > if I do the reading with ADMA disabled, the sector may be marked (as
>>> > expected)
>>> > as definitively bad block, and then reallocated. Given that the drive
>>> > has
>>> > still some few bad blocks, we have still some chances of reproducing
>>> > again
>>> > and again, but really I don't know for sure how many tries do we have.
>>>
>>> You can create bad blocks using hdparm --make-bad-sector on most
>>> drives.
>>>
>
> If I understand correctly, the lockups occur when trying to read bad
> sectors, prior to reallocating them. I have read hdparm's man page,
> but I don't understand clearly if there is going to be the same effect
> (e.g. is it going to timeout in the same way?). I can check that but
> at first I need to make my whole backup.
I think normally the drive reacts in the same way as any other kind of
bad sector, but it likely depends on the specific drive.
>
>>> So, the controller locks up the whole machine while trying to handle a
>>> UNC error. Heh, it even times out on READ_LOG_EXT during EH.
>>> Unfortunately, I'm not sure there's much we can do at this point.
>>> IIRC, NV ADMA support never really matured which is why it never got
>>> turned on by default. I wouldn't be too surprised if the issue is
>>> with the controller itself. Quite a few of these first-gen NCQ
>>> controllers were quite flaky after all. Robert should know a lot
>>> better than me tho.
>
> Ok, the point is if there is something to test before giving up
> definitively with the ADMA mode for this controller. For me it is not
> that important to have it working, but since the hardware is in place,
> my technologist heart tells me to use it. In any case, I can
> definitely live without it.
>
>>
>>
>> I don't have much great insight, but it seems like these controllers
>> definitely have some issues with error handling. From what I saw, some types
>> of errors would basically cause the controller to seize up and not respond
>> properly to CPU requests on the HT bus (there were some reports of MCE
>> errors referring to HT timeouts). I've seen the CK804 lock up Windows, I
>> think with either the NVIDIA or the default Microsoft IDE drivers installed,
>> when doing things like reading a damaged DVD on an optical drive connected
>> to the CK804 SATA controller, which leads me to suspect it's some kind of
>> hardware issue that we may not be able to get around (even not using ADMA
>> doesn't appear to be a complete solution). I've asked NVIDIA for help about
>> some of the issues that were reported but it seems like they mostly clammed
>> up on this particular subject.
>>
>> It seems like these controllers were tested with, and work fine with, hard
>> drives that don't have any bad sectors or other issues, but as soon as
>> errors start happening things start to fall apart. They came out a bit
>> before optical drives on SATA started becoming commonplace where they would
>> have had to deal with more error handling.
>
> My main concern is that the whole computer is freezed. Is there any
> additional kernel debug switch or whatever that may help in
> understanding the problem?
Turning on some or all of the libata debug options (at the cost of a
likely huge amount of output) may be useful. You can try changing the
"#undef ATA_DEBUG" and "#undef ATA_VERBOSE_DEBUG" lines in
include/linux/libata.h to #define and rebuilding the kernel. If you
can reproduce the lockup after that, it may indicate where it's
occurring, though you may still need to add more output to narrow it
down.
It's quite possible that there's no reasonable workaround, but I don't
know that anyone has taken the effort to debug this very thoroughly. I
don't have a CK804 machine anymore so I can't provide too much
first-hand assistance myself.
>
> I have seen some obscurity regarding ADMA for CK804 in the kernel
> commits, but if we can isolate and reproduce the problems, perhaps we
> can find a workaround.
>
>
> I have another (different) annoying thing: why my emails do not appear
> in the mailing list logs [1]? I'm not sure if the people subscribed to
> the list are receiving my emails, or only your responses to them.
Looks like at least this email made it to the list.
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