From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: mingo@redhat.com, x86@kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H . Peter Anvin" <hpa@zytor.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Alexei Starovoitov <ast@kernel.org>,
Alexei Starovoitov <ast@fb.com>
Subject: Re: [PATCH -tip v3 7/7] kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT
Date: Fri, 29 Sep 2017 07:44:36 -0700 [thread overview]
Message-ID: <20170929074436.f447187d99e5e78008b15234@kernel.org> (raw)
In-Reply-To: <20170929073755.ypjz6cidn7aiyxbq@gmail.com>
On Fri, 29 Sep 2017 09:37:55 +0200
Ingo Molnar <mingo@kernel.org> wrote:
>
> * Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > On Thu, 28 Sep 2017 09:22:20 +0200
> > Ingo Molnar <mingo@kernel.org> wrote:
> >
> > >
> > > * Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > >
> > > > To enable jump optimized probe with CONFIG_PREEMPT, use
> > > > synchronize_rcu_tasks() to wait for all tasks preempted
> > > > on trampoline code back on track.
> > >
> > > This sentence does not parse. It's missing a verb, but I'm not sure.
> >
> > Hmm, how about this?
> >
> > Use synchthnize_rcu_tasks() to wait for all tasks preempted
> > on trampoline code back on track so that jump optimized probe
> > can be enabled with CONFIG_PREEMPT.
>
> What's "synchthnize"? ...
Oops, it's my typo. my XPS touch pad is really unstable...
>
> More seriously, I still don't understand it. What is 'back on track'?
>
> Do you mean to say:
>
> We want to wait for all potentially preempted kprobes trampoline execution to
> have completed. This guarantees that any freed trampoline memory is not in use
> by any task in the system anymore. synchronize_rcu_tasks() gives such a
> guarantee, so use it.
Exactly, this is correct!
Thank you,
>
> or something else?
>
> Thanks,
>
> Ingo
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-09-29 14:44 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-19 9:58 [PATCH -tip v3 0/7] kprobes/x86: Preempt related enhancements Masami Hiramatsu
2017-09-19 9:59 ` [PATCH -tip v3 1/7] kprobes: Improve smoke test to check preemptible Masami Hiramatsu
2017-09-28 10:52 ` [tip:perf/core] kprobes: Improve smoke test to check preemptibility tip-bot for Masami Hiramatsu
2017-09-19 9:59 ` [PATCH -tip v3 2/7] kprobes/x86: Move get_kprobe_ctlblk in irq-disabled block Masami Hiramatsu
2017-09-28 10:52 ` [tip:perf/core] kprobes/x86: Move the get_kprobe_ctlblk() into " tip-bot for Masami Hiramatsu
2017-09-19 10:00 ` [PATCH -tip v3 3/7] kprobes: Warn if optprobe handler tries to change execution path Masami Hiramatsu
2017-09-28 10:53 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-10-10 17:02 ` [PATCH -tip v3 3/7] " Naveen N. Rao
2017-10-12 5:04 ` Masami Hiramatsu
2017-10-17 8:05 ` Naveen N. Rao
2017-09-19 10:00 ` [PATCH -tip v3 4/7] kprobes/x86: Disable preempt in optprobe Masami Hiramatsu
2017-09-28 10:53 ` [tip:perf/core] kprobes/x86: Disable preemption " tip-bot for Masami Hiramatsu
2017-09-19 10:01 ` [PATCH -tip v3 5/7] kprobes/x86: Disable preempt ftrace-based jprobe Masami Hiramatsu
2017-09-28 10:54 ` [tip:perf/core] kprobes/x86: Disable preemption in ftrace-based jprobes tip-bot for Masami Hiramatsu
2017-09-19 10:02 ` [PATCH -tip v3 6/7] kprobes/x86: Remove disable_irq from ftrace-based/optimized kprobe Masami Hiramatsu
2017-09-28 7:25 ` Ingo Molnar
2017-09-29 6:48 ` Masami Hiramatsu
2017-09-28 10:54 ` [tip:perf/core] kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes tip-bot for Masami Hiramatsu
2017-09-19 10:03 ` [PATCH -tip v3 7/7] kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT Masami Hiramatsu
2017-09-28 7:22 ` Ingo Molnar
2017-09-29 7:29 ` Masami Hiramatsu
2017-09-29 7:37 ` Ingo Molnar
2017-09-29 14:44 ` Masami Hiramatsu [this message]
2017-09-29 17:45 ` Ingo Molnar
2017-09-30 5:12 ` Masami Hiramatsu
2017-10-03 23:57 ` Steven Rostedt
2017-10-04 14:01 ` Masami Hiramatsu
2017-09-21 22:00 ` [PATCH -tip v3 0/7] kprobes/x86: Preempt related enhancements Alexei Starovoitov
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