From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
hch@infradead.org
Subject: Re: [PATCH 2/8] kill tracehook_notify_death()
Date: Mon, 27 Jun 2011 16:36:17 +0200 [thread overview]
Message-ID: <20110627143617.GC30101@htj.dyndns.org> (raw)
In-Reply-To: <20110627142136.GA5812@redhat.com>
Hello,
On Mon, Jun 27, 2011 at 04:21:36PM +0200, Oleg Nesterov wrote:
> Yes, but at the same time even __fatal_signal_pending() is too strong!
> What if the tracee exits on its own, and its sys_exit() races with
> exit_group() from another thread? In this case I think it should stop,
> but __fatal_signal_pending() is true.
>
> And worse. What if the tracee stops in PTRACE_EVENT_EXIT, and _then_
> another thread does sys_exit_group()? The tracee will be "killed".
> I do not think this is right. I think the "implicit" SIGKILL in this
> case should _not_ wake up the tracee. Only the real SIGKILL (or any
> fatal signal which mutates to SIGKILL). Otherwise we simply can't
> guarantee PTRACE_EVENT_EXIT works "reliably" in this case.
Indeed, for PTRACE_EVENT_EXIT to work properly, we would need to
discern between actual KILLs and the implicit ones.
> We have signal_group_exit()/SIGNAL_GROUP_EXIT. I think we also need
> SIGNAL_THE_REAL_SIGKILL_WAS_SENT flag. Note also we have the similar
> problems with the coredump. SIGKILL should abort it. Also, we should
> define what TIF_SIGPENDIND and interruptible wait mean after exit_signals()
> and/or exit_notify(). Some drivers (tty? I do not remember) expect that
> the exiting task can do wait_event_interruptible() and react to ^C.
Eh... that sounds very shady. Maybe we should try to remove that
weird requirement instead?
> > I don't have
> > any major problem with the original. Please go ahead.
>
> Thanks. Can I add your reviewed-by/acked-by ?
Sure, please feel free to add reviewed-by. Thanks.
--
tejun
next prev parent reply other threads:[~2011-06-27 14:36 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-17 14:50 [PATCHSET] ptrace: kill most tracehooks Tejun Heo
2011-06-17 14:50 ` [PATCH 1/7] ptrace: kill task_ptrace() Tejun Heo
2011-06-17 14:50 ` [PATCH 2/7] ptrace: introduce ptrace_event_enabled() and simplify ptrace_event() and tracehook_prepare_clone() Tejun Heo
2011-06-17 14:50 ` [PATCH 3/7] ptrace: move SIGTRAP on exec(2) logic to ptrace_event() Tejun Heo
2011-06-20 20:25 ` Oleg Nesterov
2011-06-21 7:21 ` Tejun Heo
2011-06-21 20:40 ` Oleg Nesterov
2011-06-23 8:58 ` Tejun Heo
2011-06-17 14:50 ` [PATCH 4/7] ptrace: kill trivial tracehooks Tejun Heo
2011-06-17 14:50 ` [PATCH 5/7] ptrace: kill clone/exec tracehooks Tejun Heo
2011-06-20 20:33 ` Oleg Nesterov
2011-06-21 7:24 ` Tejun Heo
2011-06-17 14:50 ` [PATCH 6/7] ptrace: kill detah tracehooks Tejun Heo
2011-06-20 19:39 ` Oleg Nesterov
2011-06-21 20:23 ` Oleg Nesterov
2011-06-23 9:24 ` Tejun Heo
2011-06-22 21:07 ` [PATCH 0/8] kill task_detached() (Was: ptrace: kill detah tracehooks) Oleg Nesterov
2011-06-22 21:08 ` [PATCH 1/8] make do_notify_parent() return bool Oleg Nesterov
2011-06-23 9:52 ` Tejun Heo
2011-06-22 21:08 ` [PATCH 2/8] kill tracehook_notify_death() Oleg Nesterov
2011-06-23 12:22 ` Tejun Heo
2011-06-23 13:21 ` Oleg Nesterov
2011-06-23 13:27 ` Tejun Heo
2011-06-23 13:28 ` Oleg Nesterov
2011-06-23 17:06 ` Oleg Nesterov
2011-06-25 14:15 ` Tejun Heo
2011-06-26 20:51 ` Oleg Nesterov
2011-06-27 8:24 ` Tejun Heo
2011-06-27 14:21 ` Oleg Nesterov
2011-06-27 14:36 ` Tejun Heo [this message]
2011-06-22 21:08 ` [PATCH 3/8] __ptrace_detach: avoid task_detached(), check do_notify_parent() Oleg Nesterov
2011-06-23 13:25 ` Tejun Heo
2011-06-22 21:09 ` [PATCH 4/8] make do_notify_parent() __must_check, update the callers Oleg Nesterov
2011-06-23 13:38 ` Tejun Heo
2011-06-22 21:09 ` [PATCH 5/8] reparent_leader: check EXIT_DEAD instead of task_detached() Oleg Nesterov
2011-06-22 21:09 ` [PATCH 6/8] kill task_detached() Oleg Nesterov
2011-06-22 21:10 ` [PATCH 7/8] do not change dead_task->exit_signal Oleg Nesterov
2011-06-22 21:10 ` [PATCH 8/8] redefine thread_group_leader() as exit_signal >= 0 Oleg Nesterov
2011-06-23 13:56 ` Tejun Heo
2011-06-17 14:50 ` [PATCH 7/7] ptrace: s/tracehook_tracer_task()/ptrace_parent()/ Tejun Heo
2011-06-20 20:16 ` Oleg Nesterov
2011-06-21 11:44 ` John Johansen
2011-06-23 9:14 ` Tejun Heo
2011-06-20 11:16 ` [PATCHSET] ptrace: kill most tracehooks Christoph Hellwig
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