From: Oleg Nesterov <oleg@redhat.com>
To: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Lennart Poettering <lennart@poettering.net>,
Kay Sievers <kay.sievers@vrfy.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Cyrill Gorcunov <gorcunov@openvz.org>,
John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Michal Hocko <mhocko@suse.com>,
Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>,
Mateusz Guzik <mguzik@redhat.com>,
linux-kernel@vger.kernel.org,
Pavel Emelyanov <xemul@virtuozzo.com>,
Konstantin Khorenko <khorenko@virtuozzo.com>
Subject: setns() && PR_SET_CHILD_SUBREAPER
Date: Mon, 23 Jan 2017 17:44:20 +0100 [thread overview]
Message-ID: <20170123164420.GA2145@redhat.com> (raw)
In-Reply-To: <20170119164346.4214-1-ptikhomirov@virtuozzo.com>
And this discussion reminds me again that I do not understand how setns()
and PR_SET_CHILD_SUBREAPER should play together... Add cc's.
Suppose we have a process P in the root namespace and another namespace X.
P does setns() and enters the X namespace.
P forks a child C.
C forks a grandchild G.
C exits.
The question is, where should we reparent the grandchild G? In the normal
case it will be reparented to X->child_reaper and this looks correct.
But lets suppose that P runs with the ->has_child_subreaper bit set. In
this case it will be reparented to P's sub-reaper or a global init, and
given that P can't control its ->has_child_subreaper flag this does not
look right to me.
I can make a simple patch but perhaps I missed something or we actually
want this (imo strange) behaviour?
Oleg.
next prev parent reply other threads:[~2017-01-23 16:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-19 16:43 [PATCH] prctl: propagate has_child_subreaper flag to every descendant Pavel Tikhomirov
2017-01-20 18:14 ` Oleg Nesterov
2017-01-22 10:00 ` Pavel Tikhomirov
2017-01-22 10:11 ` Pavel Tikhomirov
2017-01-23 11:55 ` Oleg Nesterov
2017-01-23 12:52 ` task_is_descendant() cleanup Oleg Nesterov
2017-01-25 21:59 ` Kees Cook
2017-01-30 13:49 ` Oleg Nesterov
2017-01-23 14:30 ` [PATCH] prctl: propagate has_child_subreaper flag to every descendant Pavel Tikhomirov
2017-01-23 16:06 ` Oleg Nesterov
2017-01-23 11:57 ` [PATCH] introduce the walk_process_tree() helper Oleg Nesterov
2017-01-23 12:07 ` Oleg Nesterov
2017-01-24 15:01 ` Pavel Tikhomirov
2017-01-23 16:44 ` Oleg Nesterov [this message]
2017-01-23 18:21 ` setns() && PR_SET_CHILD_SUBREAPER Eric W. Biederman
2017-01-24 14:07 ` Oleg Nesterov
2017-01-24 15:24 ` Eric W. Biederman
2017-01-30 18:16 ` Oleg Nesterov
2017-01-30 18:17 ` [PATCH] exit: fix the setns() && PR_SET_CHILD_SUBREAPER interaction Oleg Nesterov
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