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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Uladzislau Rezki <urezki@gmail.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Next Mailing List <linux-next@vger.kernel.org>
Subject: Re: linux-next: manual merge of the rcu tree with the ftrace tree
Message-ID: <20251114133532.mmdi2dca@linutronix.de>
References: <20251114135226.64831207@canb.auug.org.au>
 <20251114074255.3e535084@gandalf.local.home>
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In-Reply-To: <20251114074255.3e535084@gandalf.local.home>

On 2025-11-14 07:42:55 [-0500], Steven Rostedt wrote:
> > diff --cc kernel/trace/trace_syscalls.c
> > index e96d0063cbcf,3f699b198c56..000000000000
> > --- a/kernel/trace/trace_syscalls.c
> > +++ b/kernel/trace/trace_syscalls.c
> > @@@ -878,6 -322,8 +890,7 @@@ static void ftrace_syscall_enter(void *
> >   	 * buffer and per-cpu data require preemption to be disabled.
> >   	 */
> >   	might_fault();
> > + 	preempt_rt_guard();
> >  -	guard(preempt_notrace)();
> 
> My code made it so that preemption is not needed here but is moved later
> down for the logic that does the reading of user space data.
> 
> Note, it must have preemption disabled for all configs (including RT).
> Otherwise, the data it has can get corrupted.
> 
> Paul, can you change it so that you *do not* touch this file?

Where is preempt_rt_guard() from?

> Thanks,
> 
> -- Steve

Sebastian