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From: Oleg Nesterov <oleg@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH RESEND 1/2] tracing: syscall_*regfunc() can race with copy_process()
Date: Thu, 10 Apr 2014 15:33:05 +0200	[thread overview]
Message-ID: <20140410133305.GA12228@redhat.com> (raw)
In-Reply-To: <20140410090452.6b7677fc@gandalf.local.home>

On 04/10, Steven Rostedt wrote:
>
> On Wed, 9 Apr 2014 19:05:42 +0200
> Oleg Nesterov <oleg@redhat.com> wrote:
>
> > syscall_regfunc() and syscall_unregfunc() should set/clear
> > TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race
> > with copy_process() and miss the new child which was not added to
> > init_task.tasks list yet.
> >
> > Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT
> > under tasklist.
> >
> > While at it,
> >
> > 	- remove _irqsafe from syscall_regfunc/syscall_unregfunc,
> > 	  read_lock(tasklist) doesn't need to disable irqs.
> >
> > 	- change syscall_unregfunc() to check PF_KTHREAD to skip
> > 	  the kernel threads, ->mm != NULL is the common mistake.
> >
> > 	  Note: probably this check should be simply removed, needs
> > 	  another patch.
> >
> > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
>
> BTW, how important is this fix? Something we should aim for the current
> merge window? stable? Or can it wait till 3.16?

I think this all can wait till 3.16. The problem is really minor.

Oleg.


  reply	other threads:[~2014-04-10 13:33 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-09 16:11 [PATCH 0/5] core: Convert thread iteration to use for_each[_process]_thread APIs, 1st pile Frederic Weisbecker
2014-04-09 16:11 ` [PATCH 1/5] sched: Convert thread_group_cputime() to use for_each_thread() Frederic Weisbecker
2014-04-09 17:12   ` Oleg Nesterov
2014-04-09 17:16   ` Peter Zijlstra
2014-04-09 17:32     ` Oleg Nesterov
2014-04-09 18:30       ` Peter Zijlstra
2014-04-09 19:46         ` Oleg Nesterov
2014-04-09 19:49           ` Peter Zijlstra
2014-04-10 16:19             ` Peter Zijlstra
2014-04-10 16:32               ` Peter Zijlstra
2014-04-10 17:29               ` Oleg Nesterov
2014-04-10 17:36                 ` Peter Zijlstra
2014-04-10 17:42                   ` Peter Zijlstra
2014-04-10 19:15                   ` Oleg Nesterov
2014-04-10 20:55                     ` Peter Zijlstra
2014-04-10  7:56           ` Ingo Molnar
2014-04-09 16:11 ` [PATCH 2/5] tracepoint: Convert process iteration to use for_each_process_thread() Frederic Weisbecker
2014-04-09 16:28   ` Mathieu Desnoyers
2014-04-09 16:40     ` Frederic Weisbecker
2014-04-09 16:42     ` Steven Rostedt
2014-04-09 17:05       ` [PATCH 0/2] Was: " Oleg Nesterov
2014-04-09 17:05         ` [PATCH RESEND 1/2] tracing: syscall_*regfunc() can race with copy_process() Oleg Nesterov
2014-04-10 13:04           ` Steven Rostedt
2014-04-10 13:33             ` Oleg Nesterov [this message]
2014-04-10 13:06           ` Steven Rostedt
2014-04-10 13:34             ` Oleg Nesterov
2014-04-11 15:22               ` Steven Rostedt
2014-04-11 15:58                 ` Oleg Nesterov
2014-04-13 18:58                   ` [PATCH v2 0/3] tracing: syscall_*regfunc() fixes Oleg Nesterov
2014-04-13 18:58                     ` [PATCH v2 1/3] tracing: fix syscall_*regfunc() vs copy_process() race Oleg Nesterov
2014-04-14 23:57                       ` Frederic Weisbecker
2014-04-13 18:59                     ` [PATCH v2 2/3] tracing: change syscall_*regfunc() to check PF_KTHREAD and use for_each_process_thread() Oleg Nesterov
2014-04-13 18:59                     ` [PATCH v2 3/3] tracing: syscall_regfunc() should not skip kernel threads Oleg Nesterov
2014-04-14 23:46                     ` [PATCH v2 0/3] tracing: syscall_*regfunc() fixes Frederic Weisbecker
2014-06-18 14:23                     ` Steven Rostedt
2014-06-18 15:36                       ` Oleg Nesterov
2014-04-09 17:06         ` [PATCH RESEND 2/2] tracing: syscall_regfunc() should not skip kernel threads Oleg Nesterov
2014-04-10 13:28           ` Steven Rostedt
2014-04-10 13:38             ` Oleg Nesterov
2014-04-10 14:28               ` Steven Rostedt
2014-04-10 14:46                 ` Oleg Nesterov
2014-04-10 15:08                   ` Steven Rostedt
2014-04-10 17:57                     ` Oleg Nesterov
2014-04-10 18:14                       ` Oleg Nesterov
2014-04-10 19:00                         ` Oleg Nesterov
2014-04-10 19:13                         ` Steven Rostedt
2014-04-10 19:38                           ` Oleg Nesterov
2014-04-10 19:55                             ` Steven Rostedt
2014-04-11 12:03                               ` Oleg Nesterov
2014-04-11 12:37                                 ` Steven Rostedt
2014-04-10 13:03         ` [PATCH 0/2] Was: Convert process iteration to use for_each_process_thread() Steven Rostedt
2014-04-09 16:11 ` [PATCH 3/5] hung_task: " Frederic Weisbecker
2014-04-09 17:23   ` Oleg Nesterov
2014-04-09 16:11 ` [PATCH 4/5] procfs: Convert process iteration to use for_each_thread() Frederic Weisbecker
2014-04-09 16:11 ` [PATCH 5/5] sched: Convert tasks iteration to use for_each_process_thread() Frederic Weisbecker

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