Messages in this thread | | | Date | Fri, 22 Sep 2017 21:09:14 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 3/4] extable: Enable RCU if it is not watching in kernel_text_address() |
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On Fri, 22 Sep 2017 15:44:06 -0700 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> On Fri, Sep 22, 2017 at 06:15:46PM -0400, Steven Rostedt wrote: > > From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> > > > > If kernel_text_address() is called when RCU is not watching, it can cause an > > RCU bug because is_module_text_address() and the is_kprobe_*insn_slot() > > functions require the use of RCU. > > > > Only enable RCU if it is not currently watching before it calls > > is_module_text_address(). The use of rcu_nmi_enter() is used to enable RCU > > because kernel_text_address() can happen pretty much anywhere (like an NMI), > > and even from within an NMI. It is called via save_stack_trace() that can be > > called by any WARN() or tracing function, which can happen while RCU is not > > watching (for example, going to or coming from idle, or during CPU take down > > or bring up). > > > > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Cc: stable@vger.kernel.org > > Do we need something calling out the dependency on the first two patches, > or is that implied these days?
I believe the stable folks will simply apply patches marked for stable in the order they are applied. This is a patch series, so I don't think it will be an issue for them.
> > > Fixes: 0be964be0 ("module: Sanitize RCU usage and locking") > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > > Give or take Josh's feedback on the commit log and comment:
Yep.
> > Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Thanks!
-- Steve
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