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From: Thomas Gleixner <tglx@linutronix.de>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	bpf@vger.kernel.org, Joel Fernandes <joel@joelfernandes.org>,
	linux-trace-kernel@vger.kernel.org,
	Michael Jeanson <mjeanson@efficios.com>
Subject: Re: [PATCH resend 6/8] tracing/ftrace: Add might_fault check to syscall probes
Date: Mon, 28 Oct 2024 18:42:07 +0100	[thread overview]
Message-ID: <87cyjk2kgg.ffs@tglx> (raw)
In-Reply-To: <20240930192357.1154417-7-mathieu.desnoyers@efficios.com>

On Mon, Sep 30 2024 at 15:23, Mathieu Desnoyers wrote:
> diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
> index a3d8ac00793e..0430890cbb42 100644
> --- a/kernel/trace/trace_syscalls.c
> +++ b/kernel/trace/trace_syscalls.c
> @@ -303,6 +303,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
>  	 * Syscall probe called with preemption enabled, but the ring
>  	 * buffer and per-cpu data require preemption to be disabled.
>  	 */
> +	might_fault();
>  	guard(preempt_notrace)();

I find it odd that the might_fault() check is in all the implementations
and not in the tracepoint itself:

    if (syscall) {
        might_fault();
 	rcu_read_unlock_trace();
   } else ...     

That's where I would have expected it to be.

Thanks,

        tglx

  reply	other threads:[~2024-10-28 17:42 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-30 19:23 [PATCH resend 0/8] tracing: Allow system call tracepoints to handle page faults Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 1/8] tracing: Declare system call tracepoints with TRACE_EVENT_SYSCALL Mathieu Desnoyers
2024-10-03  9:51   ` kernel test robot
2024-10-03  9:51   ` kernel test robot
2024-09-30 19:23 ` [PATCH resend 2/8] tracing/ftrace: guard syscall probe with preempt_notrace Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 3/8] tracing/perf: " Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 4/8] tracing/bpf: " Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 5/8] tracing: Allow system call tracepoints to handle page faults Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 6/8] tracing/ftrace: Add might_fault check to syscall probes Mathieu Desnoyers
2024-10-28 17:42   ` Thomas Gleixner [this message]
2024-10-28 19:02     ` Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 7/8] tracing/perf: " Mathieu Desnoyers
2024-09-30 19:23 ` [PATCH resend 8/8] tracing/bpf: " Mathieu Desnoyers

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