From: Linus Torvalds <torvalds@linux-foundation.org>
To: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: "Russell King - ARM Linux" <linux@arm.linux.org.uk>,
"Trond Myklebust" <Trond.Myklebust@netapp.com>,
linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org,
"Marc Kleine-Budde" <mkl@pengutronix.de>,
"Uwe Kleine-König" <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
Subject: Re: still nfs problems [Was: Linux 2.6.37-rc8]
Date: Wed, 5 Jan 2011 11:18:14 -0800 [thread overview]
Message-ID: <AANLkTi=VZUxNFd7n-qwf5aiOeK5rkk8qBmo+kOpgg7up@mail.gmail.com> (raw)
In-Reply-To: <1294254337.16957.13.camel@mulgrave.site>
On Wed, Jan 5, 2011 at 11:05 AM, James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
>
> I think the solution for the kernel direct mapping problem is to take
> the expected flushes and invalidates into kmap/kunmap[_atomic].
No, we really can't do that. Most of the time, the kmap() is the only
way we access the page anyway, so flushing things would just be
stupid. Why waste time and energy on doing something pointless?
In fact, kmap() here is a total non-issue. It's not the kmap() that
introduces any virtual aliases, and never has been. It's the
"vm_map_ram()" that is the problem. Unlike the kmap(), that really
_does_ introduce a virtual alias, and is a problem for any virtual
cache.
So don't blame kmap(). It's innocent and irrelevant - the bug could
happen entirely without it (think a 64-bit address space that doesn't
even _have_ kmap, but has software that mixes vm_map_ram() with
non-mapped accesses).
Linus
next prev parent reply other threads:[~2011-01-05 19:18 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-05 19:05 still nfs problems [Was: Linux 2.6.37-rc8] James Bottomley
2011-01-05 19:18 ` Linus Torvalds [this message]
[not found] ` <AANLkTi=VZUxNFd7n-qwf5aiOeK5rkk8qBmo+kOpgg7up-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-01-05 19:36 ` James Bottomley
2011-01-05 19:36 ` James Bottomley
2011-01-05 19:49 ` Linus Torvalds
2011-01-05 20:35 ` James Bottomley
[not found] ` <1294256169.16957.18.camel-0iu6Cu4xQGLYCGPCin2YbQ@public.gmane.org>
2011-01-05 20:00 ` Russell King - ARM Linux
2011-01-05 20:00 ` Russell King - ARM Linux
2011-01-05 20:33 ` James Bottomley
2011-01-05 20:33 ` James Bottomley
2011-01-05 20:48 ` Linus Torvalds
[not found] ` <AANLkTimzzBsdtWcZtP5E_CH1hUZugGMoaHOiMdQJf764-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-01-05 21:04 ` Russell King - ARM Linux
2011-01-05 21:04 ` Russell King - ARM Linux
2011-01-05 21:08 ` Linus Torvalds
2011-01-05 21:08 ` Linus Torvalds
[not found] ` <AANLkTi=EXXBTW7oWHq3D+PHsx=thF1CpkRjn0ax2p5rm-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-01-05 21:16 ` Trond Myklebust
2011-01-05 21:16 ` Trond Myklebust
[not found] ` <1294262208.2952.4.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org>
2011-01-05 21:30 ` Linus Torvalds
2011-01-05 21:30 ` Linus Torvalds
2011-01-05 23:06 ` Trond Myklebust
2011-01-05 23:06 ` Trond Myklebust
2011-01-05 23:28 ` James Bottomley
2011-01-06 17:40 ` James Bottomley
2011-01-06 17:47 ` Trond Myklebust
2011-01-06 17:51 ` James Bottomley
2011-01-06 17:55 ` Linus Torvalds
2011-01-06 17:55 ` Linus Torvalds
2011-01-07 18:53 ` Trond Myklebust
[not found] ` <1294426405.2929.23.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org>
2011-01-07 19:02 ` Russell King - ARM Linux
2011-01-07 19:02 ` Russell King - ARM Linux
2011-01-07 19:11 ` James Bottomley
2011-01-07 19:11 ` James Bottomley
[not found] ` <1294427467.4895.66.camel-0iu6Cu4xQGLYCGPCin2YbQ@public.gmane.org>
2011-01-08 16:49 ` Trond Myklebust
2011-01-08 16:49 ` Trond Myklebust
2011-01-08 23:15 ` Trond Myklebust
2011-01-08 23:15 ` Trond Myklebust
[not found] ` <1294528551.4181.19.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org>
2011-01-10 10:50 ` Uwe Kleine-König
2011-01-10 10:50 ` Uwe Kleine-König
2011-01-10 16:25 ` Trond Myklebust
[not found] ` <1294676734.3349.10.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org>
2011-01-10 17:08 ` Marc Kleine-Budde
2011-01-10 17:08 ` Marc Kleine-Budde
2011-01-10 17:20 ` Trond Myklebust
[not found] ` <1294680035.3349.19.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org>
2011-01-10 17:26 ` Marc Kleine-Budde
2011-01-10 17:26 ` Marc Kleine-Budde
2011-01-10 19:25 ` Uwe Kleine-König
[not found] ` <20110110192552.GG24920-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2011-01-10 19:29 ` Trond Myklebust
2011-01-10 19:29 ` Trond Myklebust
2011-01-10 19:31 ` James Bottomley
2011-01-10 19:34 ` Linus Torvalds
2011-01-10 19:34 ` Linus Torvalds
2011-01-10 20:15 ` Trond Myklebust
2011-01-10 12:44 ` Marc Kleine-Budde
2011-01-10 12:44 ` Marc Kleine-Budde
2011-01-07 19:13 ` Trond Myklebust
2011-01-07 19:05 ` James Bottomley
[not found] ` <1294335614.22825.154.camel-0iu6Cu4xQGLYCGPCin2YbQ@public.gmane.org>
2011-01-06 18:05 ` Russell King - ARM Linux
2011-01-06 18:05 ` Russell King - ARM Linux
2011-01-06 18:14 ` James Bottomley
2011-01-06 18:14 ` James Bottomley
[not found] ` <1294337670.22825.199.camel-0iu6Cu4xQGLYCGPCin2YbQ@public.gmane.org>
2011-01-06 18:25 ` James Bottomley
2011-01-06 18:25 ` James Bottomley
2011-01-06 21:07 ` James Bottomley
2011-01-06 21:07 ` James Bottomley
2011-01-06 20:19 ` John Stoffel
2011-01-06 20:19 ` John Stoffel
2011-01-05 23:28 ` Linus Torvalds
2011-01-05 23:28 ` Linus Torvalds
[not found] ` <AANLkTi=SjMinMp+m726GS1iehj6cQgNy1RqSoUqKhjtv-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-01-05 23:59 ` Russell King - ARM Linux
2011-01-05 23:59 ` Russell King - ARM Linux
2011-01-05 21:16 ` James Bottomley
2011-01-05 21:16 ` James Bottomley
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