On Wed, 2010-02-24 at 11:19 -0500, Alan Stern wrote:

quoted

It is but I'm not confident the responsibility for doing that

cleanup

quoted

is at the HCD level. That would impact a lot of HCD activities that
don't need such flushing since the use of the page is purely

in-kernel.

That's right.  The HCD merely puts data wherever it's told to.  It 
doesn't know whether the destination is in the page cache, in 
userspace, or anywhere else.  The same is true for usb-storage.

I'm surprised that usb-storage has an issue here. It shouldn't afaik,
since it's just a SCSI driver (or not anymore ?) and the BIO or
filesystems handle things there no ? I haven't seen a single call to
flush_dcache_page() in any of drivers/scsi, drivers/ata or drivers/ide
when I looked...

Cheers,
Ben.