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Date: Sat, 20 Sep 2014 20:33:26 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Kirill Tkhai <tkhai@yandex.ru>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
        Kirill Tkhai <ktkhai@parallels.com>
Subject: Re: [PATCH 2/7] sched: Fix picking a task switching on other cpu
 (__ARCH_WANT_UNLOCKED_CTXSW)
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On Sat, Sep 20, 2014 at 08:51:22PM +0400, Kirill Tkhai wrote:
> From: Kirill Tkhai <ktkhai@parallels.com>
> 
> We may pick a task which is in context_switch() on other cpu at the moment.
> Parallel using of a single stack by two processes is not a good idea.

Please elaborate on who exactly that might happen. Its best to have
comprehensive changelogs for issues that fix races.