From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Anton Salikhmetov <salikhmetov@gmail.com>,
linux-mm@kvack.org, jakob@unthought.net,
linux-kernel@vger.kernel.org, valdis.kletnieks@vt.edu,
riel@redhat.com, ksm@42.dk, staubach@redhat.com,
jesper.juhl@gmail.com, a.p.zijlstra@chello.nl,
akpm@linux-foundation.org, protasnb@gmail.com, miklos@szeredi.hu,
r.e.wolff@bitwizard.nl, hidave.darkstar@gmail.com,
hch@infradead.org
Subject: Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in sys_msync()
Date: Thu, 24 Jan 2008 12:36:00 +1100 [thread overview]
Message-ID: <200801241236.01114.nickpiggin@yahoo.com.au> (raw)
In-Reply-To: <alpine.LFD.1.00.0801230836250.1741@woody.linux-foundation.org>
On Thursday 24 January 2008 04:05, Linus Torvalds wrote:
> On Wed, 23 Jan 2008, Anton Salikhmetov wrote:
> > +
> > + if (pte_dirty(*pte) && pte_write(*pte)) {
>
> Not correct.
>
> You still need to check "pte_present()" before you can test any other
> bits. For a non-present pte, none of the other bits are defined, and for
> all we know there might be architectures out there that require them to
> be non-dirty.
>
> As it is, you just possibly randomly corrupted the pte.
>
> Yeah, on all architectures I know of, it the pte is clear, neither of
> those tests will trigger, so it just happens to work, but it's still
> wrong.
Probably it can fail for !present nonlinear mappings on many
architectures.
--
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next prev parent reply other threads:[~2008-01-24 1:36 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-22 23:21 [PATCH -v8 0/4] Fixing the issue with memory-mapped file times Anton Salikhmetov
2008-01-22 23:21 ` [PATCH -v8 1/4] Massive code cleanup of sys_msync() Anton Salikhmetov
2008-01-22 23:21 ` [PATCH -v8 2/4] Update ctime and mtime for memory-mapped files Anton Salikhmetov
2008-01-23 18:03 ` Linus Torvalds
2008-01-23 23:14 ` Anton Salikhmetov
2008-01-22 23:21 ` [PATCH -v8 3/4] Enable the MS_ASYNC functionality in sys_msync() Anton Salikhmetov
2008-01-23 8:47 ` Peter Zijlstra
2008-01-23 8:51 ` Peter Zijlstra
2008-01-23 9:34 ` Miklos Szeredi
2008-01-23 9:51 ` Miklos Szeredi
2008-01-23 13:09 ` Anton Salikhmetov
2008-01-23 12:53 ` Anton Salikhmetov
2008-01-23 9:41 ` Miklos Szeredi
2008-01-23 17:05 ` Linus Torvalds
2008-01-23 17:26 ` Anton Salikhmetov
2008-01-23 17:41 ` Peter Zijlstra
2008-01-23 19:35 ` Linus Torvalds
2008-01-23 19:55 ` Miklos Szeredi
2008-01-23 21:00 ` Linus Torvalds
2008-01-23 21:16 ` Miklos Szeredi
2008-01-23 21:36 ` Linus Torvalds
2008-01-23 22:29 ` Hugh Dickins
2008-01-23 22:41 ` Linus Torvalds
2008-01-24 0:03 ` Hugh Dickins
2008-01-24 0:05 ` Miklos Szeredi
2008-01-24 0:11 ` Linus Torvalds
2008-01-24 1:36 ` Nick Piggin [this message]
2008-01-24 18:56 ` Matt Mackall
2008-01-22 23:21 ` [PATCH -v8 4/4] The design document for memory-mapped file times update Anton Salikhmetov
2008-01-23 9:26 ` Miklos Szeredi
2008-01-23 10:37 ` Anton Salikhmetov
2008-01-23 10:53 ` Miklos Szeredi
2008-01-23 11:16 ` Miklos Szeredi
2008-01-23 12:25 ` Anton Salikhmetov
2008-01-23 13:55 ` Miklos Szeredi
2008-01-25 16:27 ` Randy Dunlap
2008-01-25 16:40 ` Anton Salikhmetov
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