From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Kosuke Tatsukawa <tatsu@ab.jp.nec.com>,
Gleb Natapov <gleb@kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kvm: fix waitqueue_active without memory barrier in virt/kvm/async_pf.c
Date: Fri, 9 Oct 2015 12:24:11 +0200 [thread overview]
Message-ID: <561795CB.30006@redhat.com> (raw)
In-Reply-To: <20151009085040.GZ7520@twins.programming.kicks-ass.net>
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
next prev parent reply other threads:[~2015-10-09 10:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-09 0:35 [PATCH] kvm: fix waitqueue_active without memory barrier in virt/kvm/async_pf.c Kosuke Tatsukawa
2015-10-09 8:45 ` Paolo Bonzini
2015-10-09 8:50 ` Peter Zijlstra
2015-10-09 10:24 ` Paolo Bonzini [this message]
2015-10-09 9:04 ` Kosuke Tatsukawa
2015-10-09 10:26 ` Paolo Bonzini
2015-10-09 12:21 ` Kosuke Tatsukawa
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