On Wed, Aug 07, 2013 at 03:50:42PM +0800, Ming Lei wrote:
> On Wed, Aug 7, 2013 at 1:41 PM, Christoffer Dall
> <christoffer.d...@linaro.org> wrote:
> > Hi all,
> >
> > I've found that booting a recent kernel (and as far back as 3.9 at
> > least) I get a kernel bug during boot with VM debugging enabled. I
> > haven't had time to dig further into it, but wanted to check if this is
> > a known issue?
>
> Remember Catalin introduced the flush_dcache_page() to fix
> cache incoherency problem when PIO reading from USB mass
> storage device to mapped page, so the flush should not need
> for pages not in page cache.
>
> Care to test below patch to see if the problem can be fixed?
>
> diff --git a/drivers/usb/host/isp1760-hcd.c b/drivers/usb/host/isp1760-hcd.c
> index 2facee5..9d47c71 100644
> --- a/drivers/usb/host/isp1760-hcd.c
> +++ b/drivers/usb/host/isp1760-hcd.c
> @@ -707,8 +707,12 @@ __acquires(priv->lock)
> void *ptr;
> for (ptr = urb->transfer_buffer;
> ptr < urb->transfer_buffer + urb->transfer_buffer_length;
> - ptr += PAGE_SIZE)
> - flush_dcache_page(virt_to_page(ptr));
> + ptr += PAGE_SIZE) {
> + struct page *page = virt_to_page(ptr);
> + if (PageSlab(page))
> + break;
> + flush_dcache_page(page);
> + }
> }
>
> /* complete() can reenter this HCD */
>
Yep, that fixes it. Thanks!!
-Christoffer
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