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SubjectRe: Possible memory ordering bug in page reclaim?
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On Sat, Oct 15, 2005 at 06:00:18PM +0000, Andrea Arcangeli wrote:
>
> Note that the barrier in atomic_add_negative is useless here because it
> happens way too late, _after_ the count is decremented (not _before_)
> so the decreased count could be already visible to the other cpu.

Could you please point me to an architecture that does this?

This assumption is in fact made in a number of places in the kernel
where constructs such as atomic_add_negative or atomic_dec_and_test
are used and assumed to imply a memory barrier.

Thanks,
--
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