Re: 3.1.3 2.6.37.6 2.6.33.4 kernel bug in pata_oldpiix driver

From: Stefano Laporta
Date: Fri Dec 16 2011 - 18:13:31 EST


I have been able to find another similar PC still working, a Pentium 90MHz
with Intel i430FX chipset, 32MB of RAM, an 1.2GB HD and a CD-ROM.
The kernels which crash on my Pentium 133MHz crash even on the Pentium 90,
giving exactly the same error messages.

So it seems not to be a problem of a single machine.

I switched on the debug options in kernel configuration, but this makes the bug (apparently) disappear. Memory overwrites are always difficult to catch.


On Mon, 28 Nov 2011, Alan Cox wrote:

BUG: unable to handle kernel paging request at 45230451

That looks like junk from somewhere.

IP: [<c17bb1f3>] oldpiix_set_dmamode+0xb3/0x120

[<c17bb3b0>] ? oldpiix_qc_issue+0x40/0x60
[<c1788d8a>] ? ata_qc_issue+0x1ea/0x330

So we were issuing a command, we called the oldpiix code, it decided that
the timings were not loaded for this drive (ie it was those loaded for
the other device on the bus)

It will then have gone into oldpiix_set_piomode which ran succesfully
implying that ap and adev were valid at that point but seem to have
mysteriously gone invalid later.

No idea, and the fact that changing things like the pre-empt behaviour or
build options makes me wonder if it was scribbled on from elsewhere.



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