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Date: Wed, 12 Aug 2015 19:24:18 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
        Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>, David Howells <dhowells@redhat.com>,
        linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Rik van Riel <riel@redhat.com>,
        Vladimir Davydov <vdavydov@parallels.com>,
        Ricky Zhou <rickyz@chromium.org>, Julien Tinnes <jln@google.com>
Subject: Re: [PATCH 2/2] userns,pidns: Force thread group sharing, not
	signal handler sharing
Message-ID: <20150812172418.GA6370@redhat.com>
References: <20150728171500.GA2871@www.outflux.net> <20150728143504.5aa996ba5955522a19c2d5f1@linux-foundation.org> <20150728221111.GA23391@node.dhcp.inet.fi> <20150805172356.GA20490@redhat.com> <87wpx9sjhq.fsf@x220.int.ebiederm.org> <87614tr2jd.fsf@x220.int.ebiederm.org> <20150806130629.GA4728@redhat.com> <20150806134426.GA6843@redhat.com> <871tf9cnbi.fsf_-_@x220.int.ebiederm.org> <87oaidb8n6.fsf_-_@x220.int.ebiederm.org>
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On 08/11, Eric W. Biederman wrote:
>
> The code that places signals in signal queues computes the uids, gids,
> and pids at the time the signals are enqueued.  Which means that tasks
> that share signal queues must be in the same pid and user namespaces.
>
> Sharing signal handlers is fine, but bizarre.
>
> So make the code in fork and userns_install clearer by only testing
> for what is functionally necessary.
>
> Also update the comment in unshare about unsharing a user namespace to
> be a little more explicit and make a little more sense.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Acked-by: Oleg Nesterov <oleg@redhat.com>



But: Eric, Andrew, this means that

	user_ns-use-correct-check-for-single-threadedness.patch

in -mm tree should be dropped.

Oleg.