From: Frederic Weisbecker <fweisbec@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Li Zefan <lizf@cn.fujitsu.com>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
stable@kernel.org
Subject: Re: [PATCH 5/5] tracing: Do not record user stack trace from NMI context
Date: Wed, 17 Mar 2010 03:08:01 +0100 [thread overview]
Message-ID: <20100317020759.GE5258@nowhere> (raw)
In-Reply-To: <1268585920.13400.14.camel@localhost>
On Sun, Mar 14, 2010 at 12:58:40PM -0400, Steven Rostedt wrote:
> On Sun, 2010-03-14 at 11:27 +0100, Frederic Weisbecker wrote:
>
> >
> > Wow, that's a race :)
> >
> > In perf this is dealt with a special copy_from_user_nmi()
> > (see in arch/x86/kernel/cpu/perf_event.c)
> >
> > May be save_stack_trace_user() should use that instead
> > of a __copy_from_user_inatomic() based thing, just to
> > cover such NMI corner race case.
> >
>
> Yeah, we should move the __copy_from_user_nmi() out of the perf code and
> into the normal uaccess code. Then we could do as you suggest, and have
> the stack code do:
>
> if (in_nmi())
> __copy_from_user_nmi();
> else
> __copy_from_user_inatomic();
>
> Or maybe it would be best to have the __copy_from_user_inatomic() handle
> it.
Yeah, agreed.
next prev parent reply other threads:[~2010-03-17 2:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-13 2:56 [PATCH 0/5][GIT PULL][2.6.34] tracing: urgent fixes Steven Rostedt
2010-03-13 2:56 ` [PATCH 1/5] ring-buffer: Move disabled check into preempt disable section Steven Rostedt
2010-03-13 2:56 ` [PATCH 2/5] function-graph: Init curr_ret_stack with ret_stack Steven Rostedt
2010-03-14 10:10 ` Frederic Weisbecker
2010-03-13 2:56 ` [PATCH 3/5] tracing: Use same local variable when resetting the ring buffer Steven Rostedt
2010-03-13 2:56 ` [PATCH 4/5] tracing: Disable buffer switching when starting or stopping trace Steven Rostedt
2010-03-13 2:57 ` [PATCH 5/5] tracing: Do not record user stack trace from NMI context Steven Rostedt
2010-03-14 10:27 ` Frederic Weisbecker
2010-03-14 15:28 ` Steven Rostedt
2010-03-14 16:58 ` Steven Rostedt
2010-03-17 2:08 ` Frederic Weisbecker [this message]
2010-03-14 22:05 ` John Kacur
2010-03-14 22:29 ` Steven Rostedt
2010-03-13 7:25 ` [PATCH 0/5][GIT PULL][2.6.34] tracing: urgent fixes Ingo Molnar
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