From: "David S. Miller" <davem@davemloft.net>
To: torvalds@osdl.org
Cc: herbert@gondor.apana.org.au, benh@kernel.crashing.org,
hugh@veritas.com, paulus@samba.org, anton@samba.org,
nickpiggin@yahoo.com.au, akpm@osdl.org, andrea@suse.de,
linux-kernel@vger.kernel.org
Subject: Re: Possible memory ordering bug in page reclaim?
Date: Sat, 15 Oct 2005 12:29:38 -0700 (PDT) [thread overview]
Message-ID: <20051015.122938.14078749.davem@davemloft.net> (raw)
In-Reply-To: <Pine.LNX.4.64.0510150945460.23590@g5.osdl.org>
From: Linus Torvalds <torvalds@osdl.org>
Date: Sat, 15 Oct 2005 09:57:47 -0700 (PDT)
> On Sat, 15 Oct 2005, Herbert Xu wrote:
> >
> > Yes atomic_add_negative should always be a barrier.
>
> I disagree. That would be very expensive on anything but x86, where it
> just happens to be true for other reasons. Atomics do _not_ implement
> barriers.
When they return values, they are defined to be barriers.
It's even on the documentation :-)
next prev parent reply other threads:[~2005-10-15 19:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-15 3:28 Nick Piggin
2005-10-15 6:17 ` Hugh Dickins
2005-10-15 7:43 ` Benjamin Herrenschmidt
2005-10-15 8:00 ` Herbert Xu
2005-10-15 16:57 ` Linus Torvalds
2005-10-15 19:29 ` David S. Miller [this message]
2005-10-15 22:17 ` Benjamin Herrenschmidt
2005-10-16 0:04 ` Nick Piggin
2005-10-15 8:59 ` Nick Piggin
2005-10-15 12:08 ` Herbert Xu
2005-10-15 13:35 ` Nick Piggin
2005-10-15 18:00 ` Andrea Arcangeli
2005-10-15 19:48 ` Herbert Xu
2005-10-15 20:07 ` Andrea Arcangeli
2005-10-15 23:07 ` David S. Miller
2005-10-16 19:36 ` Ivan Kokshaysky
2005-10-17 4:29 ` David S. Miller
2005-10-17 7:23 ` Ivan Kokshaysky
2005-10-17 11:28 ` Andrea Arcangeli
2005-10-15 22:16 ` Benjamin Herrenschmidt
2005-10-15 23:13 ` David S. Miller
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