Re: Possible memory ordering bug in page reclaim?

[Benjamin Herrenschmidt]

On Sat, 2005-10-15 at 12:29 -0700, David S. Miller wrote:
> From: Linus Torvalds <torvalds@xxxxxxxx>
> 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 :-)

Ahhh, good to know :)

/me should read the documentation sometimes....

Ben.

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