On Wed, Jul 18, 2007 at 05:53:39PM +0900, Tejun Heo wrote:

David Shaw wrote:

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It fails whether I use a raw /dev/sdd or partition it into one large
/dev/sdd1, or partition into multiple partitions.  sata_sil24 seems to
work by itself, as does dm, but as soon as I mix sata_sil24+dm, I get
corruption.

Hmmmm.... Can you reproduce the corruption by accessing both devices
simultaneously without using dm?  Considering ich5 does fine, it looks
like hardware and/or driver problem and I really wanna rule out dm.

I think I wasn't clear enough before.  The corruption happens when I
use dm to create two dm mappings that both reside on the same real
device.  Using two different devices, or two different partitions on
the same physical device works properly.  ich5 does fine with these 3
tests, but sata_sil24 fails:

 * /dev/sdd, create 2 dm linear mappings on it, mke2fs and use those
   dm "devices" == corruption

 * Partition /dev/sdd into /dev/sdd1 and /dev/sdd2, mke2fs and use
   those partitions == no corruption

 * Partition /dev/sdd into /dev/sdd1 and /dev/sdd2, create 2 dm linear
   mappings on /dev/sdd1, mke2fs and use those dm "devices" ==
   corruption

I'm not sure whether this is problem of sata_sil24 or dm layer.  Cc'ing
linux-raid for help.  How much memory do you have?  One big difference
between ata_piix and sata_sil24 is that sil24 can handle 64bit DMA.
Maybe dma mapping or something interacts weirdly with dm there?

The machine has 640 megs of RAM.  FWIW, I tried this with 512 megs of
RAM with the same results.  Running Memtest86+ shows the memory is
good.

David