Re: still nfs problems [Was: Linux 2.6.37-rc8]

From: Russell King - ARM Linux
Date: Wed Jan 05 2011 - 14:07:58 EST

On Wed, Jan 05, 2011 at 01:55:05PM -0500, Trond Myklebust wrote:
> On Wed, 2011-01-05 at 18:27 +0000, Russell King - ARM Linux wrote:
> > I do still think you need _something_ there, otherwise data can remain
> > in the direct map alias and not be visible via the vmap alias. I don't
> > see that we have anything in place to handle this at present though.
> Is that perhaps what flush_kernel_dcache_page() is supposed to do?

Well, given how we have things currently setup on ARM, this ends up
being a no-op - as new page cache pages are marked dirty and their
flushing done at the point when they're mapped into userspace.

I guess we could do the flushing there and mark the page clean, but
it'd need some careful examination of various code paths to confirm
that it's safe - we may be avoiding this because some ARM arch
versions need to manually IPI cache flushes to other cores (which
can only be done with IRQs enabled.)

So, I don't think it'll do at the present time.
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