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Date: Thu, 28 Jan 2016 19:25:41 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Davidlohr Bueso <dave@stgolabs.net>, Ingo Molnar <mingo@kernel.org>,
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        the arch/x86 maintainers <x86@kernel.org>,
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        Borislav Petkov <bp@alien8.de>, Mike Galbraith <bitbucket@online.de>,
        Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, Len Brown <len.brown@intel.com>
Subject: Re: [PATCH v5 4/5] x86: use mb() around clflush
Message-ID: <20160128182541.GW6356@twins.programming.kicks-ass.net>
References: <1453921746-16178-1-git-send-email-mst@redhat.com>
 <1453921746-16178-5-git-send-email-mst@redhat.com>
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On Thu, Jan 28, 2016 at 07:02:51PM +0200, Michael S. Tsirkin wrote:
> commit f8e617f4582995f7c25ef25b4167213120ad122b ("sched/idle/x86:
> Optimize unnecessary mwait_idle() resched IPIs") adds
> memory barriers around clflush, but this seems wrong
> for UP since barrier() has no effect on clflush.
> We really want mfence so switch to mb() instead.
> 
> Cc: Mike Galbraith <bitbucket@online.de>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>