Re: [PATCH] kvm: fix waitqueue_active without memory barrier in virt/kvm/async_pf.c

[Paolo Bonzini]

On 09/10/2015 10:50, Peter Zijlstra wrote:
> Not having actually read or thought about the issue at hand, its
> perfectly valid to pair an smp_mb() with either spin_lock() or
> spin_unlock().
> 
> IOW. MB <-> {ACQUIRE, RELEASE} is a valid pairing.

In this case it's an smp_mb() (store-load barrier) being paired with
another smp_mb(), so spin_unlock()'s release is not enough.

Paolo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/