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SubjectRe: [PATCH] Call flush_dcache_page around PIO data transfers in libata-aff.c
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On Wed, 2010-03-03 at 08:24 +0000, Sebastian Andrzej Siewior wrote:
> > drivers/ata/libata-sff.c | 6 ++++++
> > 1 files changed, 6 insertions(+), 0 deletions(-)
> >
> >diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
> >index 741065c..3d3c854 100644
> >--- a/drivers/ata/libata-sff.c
> >+++ b/drivers/ata/libata-sff.c
> >@@ -893,6 +896,9 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
> > do_write);
> > }
> >
> >+ if (!do_write)
> >+ flush_dcache_page(page);
> >+
> > qc->curbytes += qc->sect_size;
> > qc->cursg_ofs += qc->sect_size;
>
> That part got merged and it leads to a BUG if CONFIG_DEBUG_VM is
> enabled. My mips box and arm use page_mapping() in flush_dcache_page()
> which has VM_BUG_ON(PageSlab(page)) in it.
>
> Any comments on that?

There is a long thread on USB HCD and cache coherency on ARM which I
started pretty much at the same time with the libata-sff change. I need
to do some testing but in the view of the discussions in the other
thread, we may not need this patch at all:

http://thread.gmane.org/gmane.linux.usb.general/27072

Basically, the meaning of PG_arch_1 should be page clean rather than
page dirty.

--
Catalin


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