From: Keith Packard <keithp@keithp.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Daniel Vetter <daniel@ffwll.ch>,
Chris Wilson <chris@chris-wilson.co.uk>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
intel-gfx <intel-gfx@lists.freedesktop.org>,
stable@kernel.org, linux-kernel <linux-kernel@vger.kernel.org>,
"Morton\, Andrew" <akpm@linux-foundation.org>
Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915: properly prefault for pread/pwrite
Date: Thu, 03 Nov 2011 14:06:55 -0700 [thread overview]
Message-ID: <yunzkgcrk40.fsf@aiko.keithp.com> (raw)
In-Reply-To: <20111023221157.GH2953@phenom.ffwll.local>
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On Mon, 24 Oct 2011 00:11:57 +0200, Daniel Vetter <daniel@ffwll.ch> wrote:
> This patch only fixes things up so that we prefault the entire page range
> and not just the first PAGE_SIZE bytes (i.e. at most 2 pages). So I don't
> see the risk of extending the current behaviour to all pages. Userspace
> can already see these zero writes, but only when doing something stupid.
When we posted a patch to instead fix fault_in_pages_writeable, Andrew
complained that we'd have modified memory even on a short read, which
wasn't considered polite. Could we read/write the same value and avoid
that problem?
Also, we should be fixing fault_in_pages_* going forward, rather than
kludging in more code. And, we'd get to remove the version in ntfs,
which should end in a patch that removes more code than it adds...
--
keith.packard@intel.com
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next parent reply other threads:[~2011-11-03 21:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1317203844-2930-1-git-send-email-daniel.vetter@ffwll.ch>
[not found] ` <1317203844-2930-2-git-send-email-daniel.vetter@ffwll.ch>
[not found] ` <f80fcd$212d29@fmsmga001.fm.intel.com>
[not found] ` <20111023101830.GE2953@phenom.ffwll.local>
[not found] ` <yun7h3vbjgc.fsf@aiko.keithp.com>
[not found] ` <20111023221157.GH2953@phenom.ffwll.local>
2011-11-03 21:06 ` Keith Packard [this message]
2011-11-03 22:10 ` [Intel-gfx] [PATCH 2/2] drm/i915: properly prefault for pread/pwrite Daniel Vetter
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