From: Peter Zijlstra <peterz@infradead.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
rostedt@goodmis.org, mingo@kernel.org,
gregkh@linuxfoundation.org, gustavo@embeddedor.com,
tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
luto@kernel.org, tony.luck@intel.com, frederic@kernel.org,
dan.carpenter@oracle.com, mhiramat@kernel.org
Subject: Re: [PATCH v4 01/27] lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions
Date: Mon, 24 Feb 2020 11:10:50 +0100 [thread overview]
Message-ID: <20200224101050.GE14897@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200222030843.GA191380@google.com>
On Fri, Feb 21, 2020 at 10:08:43PM -0500, Joel Fernandes wrote:
> On Fri, Feb 21, 2020 at 02:34:17PM +0100, Peter Zijlstra wrote:
> > nmi_enter() does lockdep_off() and hence lockdep ignores everything.
> >
> > And NMI context makes it impossible to do full IN-NMI tracking like we
> > do IN-HARDIRQ, that could result in graph_lock recursion.
>
> The patch makes sense to me.
>
> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
>
> NOTE:
> Also, I was wondering if we can detect the graph_lock recursion case and
> avoid doing anything bad, that way we enable more of the lockdep
> functionality for NMI where possible. Not sure if the suggestion makes sense
> though!
Yeah, I considered playing trylock games, but figured I shouldn't make
it more complicated that it needs to be.
next prev parent reply other threads:[~2020-02-24 10:11 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 13:34 [PATCH v4 00/27] tracing vs world Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 01/27] lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions Peter Zijlstra
2020-02-21 15:08 ` Steven Rostedt
2020-02-21 20:25 ` Peter Zijlstra
2020-02-21 20:28 ` Steven Rostedt
2020-02-21 22:01 ` Frederic Weisbecker
2020-02-22 3:08 ` Joel Fernandes
2020-02-24 10:10 ` Peter Zijlstra [this message]
2020-02-25 2:12 ` Joel Fernandes
2020-03-20 12:58 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 02/27] hardirq/nmi: Allow nested nmi_enter() Peter Zijlstra
2020-02-21 22:21 ` Frederic Weisbecker
2020-02-24 12:13 ` Petr Mladek
2020-02-25 1:30 ` Frederic Weisbecker
2020-02-24 16:13 ` Peter Zijlstra
2020-02-25 3:09 ` Frederic Weisbecker
2020-02-25 15:41 ` Peter Zijlstra
2020-02-25 16:21 ` Frederic Weisbecker
2020-02-25 22:10 ` Frederic Weisbecker
2020-02-27 9:10 ` Peter Zijlstra
2020-02-27 13:34 ` Frederic Weisbecker
2020-02-21 13:34 ` [PATCH v4 03/27] x86/entry: Flip _TIF_SIGPENDING and _TIF_NOTIFY_RESUME handling Peter Zijlstra
2020-02-21 16:14 ` Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 04/27] x86/mce: Delete ist_begin_non_atomic() Peter Zijlstra
2020-02-21 19:07 ` Andy Lutomirski
2020-02-21 23:40 ` Frederic Weisbecker
2020-02-21 13:34 ` [PATCH v4 05/27] x86: Replace ist_enter() with nmi_enter() Peter Zijlstra
2020-02-21 19:05 ` Andy Lutomirski
2020-02-21 20:22 ` Peter Zijlstra
2020-02-24 10:43 ` Peter Zijlstra
2020-02-24 16:27 ` Steven Rostedt
2020-02-24 16:34 ` Peter Zijlstra
2020-02-24 16:47 ` Steven Rostedt
2020-02-24 21:31 ` Peter Zijlstra
2020-02-24 22:02 ` Steven Rostedt
2020-02-26 10:25 ` Peter Zijlstra
2020-02-26 13:16 ` Peter Zijlstra
2020-02-26 10:27 ` Peter Zijlstra
2020-02-26 15:20 ` Steven Rostedt
2020-03-07 1:53 ` Masami Hiramatsu
2020-02-21 13:34 ` [PATCH v4 06/27] x86/doublefault: Remove memmove() call Peter Zijlstra
2020-02-21 19:10 ` Andy Lutomirski
2020-02-21 13:34 ` [PATCH v4 07/27] rcu: Make RCU IRQ enter/exit functions rely on in_nmi() Peter Zijlstra
2020-02-26 0:23 ` Frederic Weisbecker
2020-02-21 13:34 ` [PATCH v4 08/27] rcu/kprobes: Comment why rcu_nmi_enter() is marked NOKPROBE Peter Zijlstra
2020-02-26 0:27 ` Frederic Weisbecker
2020-02-21 13:34 ` [PATCH v4 09/27] rcu: Rename rcu_irq_{enter,exit}_irqson() Peter Zijlstra
2020-02-21 20:21 ` Steven Rostedt
2020-02-24 10:24 ` Peter Zijlstra
2020-02-26 0:35 ` Frederic Weisbecker
2020-02-21 13:34 ` [PATCH v4 10/27] rcu: Mark rcu_dynticks_curr_cpu_in_eqs() inline Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 11/27] rcu,tracing: Create trace_rcu_{enter,exit}() Peter Zijlstra
2020-03-06 11:50 ` Peter Zijlstra
2020-03-06 12:40 ` Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 12/27] sched,rcu,tracing: Avoid tracing before in_nmi() is correct Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 13/27] x86,tracing: Add comments to do_nmi() Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 14/27] perf,tracing: Prepare the perf-trace interface for RCU changes Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 15/27] tracing: Employ trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 16/27] tracing: Remove regular RCU context for _rcuidle tracepoints (again) Peter Zijlstra
2020-03-06 10:43 ` Peter Zijlstra
2020-03-06 11:31 ` Peter Zijlstra
2020-03-06 15:51 ` Alexei Starovoitov
2020-03-06 16:04 ` Mathieu Desnoyers
2020-03-06 17:55 ` Steven Rostedt
2020-03-06 18:45 ` Joel Fernandes
2020-03-06 18:59 ` Steven Rostedt
2020-03-06 19:14 ` Joel Fernandes
2020-03-06 20:22 ` Mathieu Desnoyers
2020-03-06 20:45 ` Steven Rostedt
2020-03-06 20:55 ` Mathieu Desnoyers
2020-03-06 21:06 ` Steven Rostedt
2020-03-06 23:10 ` Alexei Starovoitov
2020-03-06 17:21 ` Joel Fernandes
2020-02-21 13:34 ` [PATCH v4 17/27] perf,tracing: Allow function tracing when !RCU Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 18/27] x86/int3: Ensure that poke_int3_handler() is not traced Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 19/27] locking/atomics, kcsan: Add KCSAN instrumentation Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 20/27] asm-generic/atomic: Use __always_inline for pure wrappers Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 21/27] asm-generic/atomic: Use __always_inline for fallback wrappers Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 22/27] compiler: Simple READ/WRITE_ONCE() implementations Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 23/27] locking/atomics: Flip fallbacks and instrumentation Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 24/27] x86/int3: Avoid atomic instrumentation Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 25/27] lib/bsearch: Provide __always_inline variant Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 26/27] x86/int3: Inline bsearch() Peter Zijlstra
2020-02-21 13:34 ` [PATCH v4 27/27] x86/int3: Ensure that poke_int3_handler() is not sanitized Peter Zijlstra
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