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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 5 Jan 2011 15:28:53 -0800
Message-ID: <AANLkTi=SjMinMp+m726GS1iehj6cQgNy1RqSoUqKhjtv@mail.gmail.com>
Subject: Re: still nfs problems [Was: Linux 2.6.37-rc8]
To: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        =?ISO-8859-1?Q?Uwe_Kleine=2DK=F6nig?=
	<u.kleine-koenig@pengutronix.de>,
        Marc Kleine-Budde <m.kleine-budde@pengutronix.de>,
        linux-arm-kernel@lists.infradead.org,
        Parisc List <linux-parisc@vger.kernel.org>, linux-arch@vger.kernel.org
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On Wed, Jan 5, 2011 at 3:06 PM, Trond Myklebust
<Trond.Myklebust@netapp.com> wrote:
>
> Yes. The fix I sent out was a call to invalidate_kernel_vmap_range(),
> which takes care of invalidating the cache prior to a virtual address
> read.
>
> My question was specifically about the write through the regular kernel
> mapping: according to Russell and my reading of the cachetlb.txt
> documentation, flush_dcache_page() is only guaranteed to have an effect
> on page cache pages.

I don't think that should ever matter. It's not like the hardware can
know whether it's a dcache page or not.

And if the sw implementation cares, it's doing something really odd.
But who knows - there's a lot of crap out there, and people sometimes
do really odd things to work around the brokenness of a VIVT cache
with aliases.

                       Linus