From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Greg KH <gregkh@linuxfoundation.org>,
gustavo@embeddedor.com, Thomas Gleixner <tglx@linutronix.de>,
paulmck@kernel.org, Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Tony Luck <tony.luck@intel.com>,
Frederic Weisbecker <frederic@kernel.org>,
Dan Carpenter <dan.carpenter@oracle.com>,
Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH v3 02/22] x86,mce: Delete ist_begin_non_atomic()
Date: Wed, 19 Feb 2020 18:33:58 +0100 [thread overview]
Message-ID: <20200219173358.GP18400@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CALCETrWBEDjenqze3wVc6TkUt_g+OFx9TQbYysLH+6fku=aWjQ@mail.gmail.com>
On Wed, Feb 19, 2020 at 09:21:48AM -0800, Andy Lutomirski wrote:
> On Wed, Feb 19, 2020 at 9:13 AM Borislav Petkov <bp@alien8.de> wrote:
> >
> > On Wed, Feb 19, 2020 at 03:47:26PM +0100, Peter Zijlstra wrote:
> > > Subject: Re: [PATCH v3 02/22] x86,mce: Delete ist_begin_non_atomic()
> >
> > x86/mce: ...
> >
> > > It is an abomination; and in prepration of removing the whole
> > > ist_enter() thing, it needs to go.
> > >
> > > Convert #MC over to using task_work_add() instead; it will run the
> > > same code slightly later, on the return to user path of the same
> > > exception.
> >
> > That's fine because the error happened in userspace.
>
> Unless there is a signal pending and the signal setup code is about to
> hit the same failed memory. I suppose we can just treat cases like
> this as "oh well, time to kill the whole system".
>
> But we should genuinely agree that we're okay with deferring this handling.
It doesn't delay much. The moment it does that local_irq_enable() it's
subject to preemption, just like it is on the return to user path.
Do you really want to create code that unwinds enough of nmi_enter() to
get you to a preemptible context? *shudder*
next prev parent reply other threads:[~2020-02-19 17:34 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-19 14:47 [PATCH v3 00/22] tracing vs world Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 01/22] hardirq/nmi: Allow nested nmi_enter() Peter Zijlstra
2020-02-19 15:31 ` Steven Rostedt
2020-02-19 16:56 ` Borislav Petkov
2020-02-19 17:07 ` Peter Zijlstra
2020-02-20 8:41 ` Will Deacon
2020-02-20 9:19 ` Marc Zyngier
2020-02-20 13:18 ` Petr Mladek
2020-02-19 14:47 ` [PATCH v3 02/22] x86,mce: Delete ist_begin_non_atomic() Peter Zijlstra
2020-02-19 17:13 ` Borislav Petkov
2020-02-19 17:21 ` Andy Lutomirski
2020-02-19 17:33 ` Peter Zijlstra [this message]
2020-02-19 22:12 ` Andy Lutomirski
2020-02-19 22:33 ` Luck, Tony
2020-02-19 22:48 ` Andy Lutomirski
2020-02-20 7:39 ` Peter Zijlstra
2020-02-19 17:42 ` Borislav Petkov
2020-02-19 17:46 ` Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 03/22] x86: Replace ist_enter() with nmi_enter() Peter Zijlstra
2020-02-20 10:54 ` Borislav Petkov
2020-02-20 12:11 ` Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 04/22] x86/doublefault: Make memmove() notrace/NOKPROBE Peter Zijlstra
2020-02-19 15:36 ` Steven Rostedt
2020-02-19 15:40 ` Peter Zijlstra
2020-02-19 15:55 ` Steven Rostedt
2020-02-19 15:57 ` Peter Zijlstra
2020-02-19 16:04 ` Peter Zijlstra
2020-02-19 16:12 ` Steven Rostedt
2020-02-19 16:27 ` Paul E. McKenney
2020-02-19 16:34 ` Peter Zijlstra
2020-02-19 16:46 ` Paul E. McKenney
2020-02-19 17:05 ` Steven Rostedt
2020-02-20 12:17 ` Borislav Petkov
2020-02-20 12:37 ` Peter Zijlstra
2020-02-19 15:47 ` Steven Rostedt
2020-02-19 14:47 ` [PATCH v3 05/22] rcu: Make RCU IRQ enter/exit functions rely on in_nmi() Peter Zijlstra
2020-02-19 16:31 ` Paul E. McKenney
2020-02-19 16:37 ` Peter Zijlstra
2020-02-19 16:45 ` Paul E. McKenney
2020-02-19 17:03 ` Peter Zijlstra
2020-02-19 17:42 ` Paul E. McKenney
2020-02-19 17:16 ` [PATCH] rcu/kprobes: Comment why rcu_nmi_enter() is marked NOKPROBE Steven Rostedt
2020-02-19 17:18 ` Joel Fernandes
2020-02-19 17:41 ` Paul E. McKenney
2020-02-20 5:54 ` Masami Hiramatsu
2020-02-19 14:47 ` [PATCH v3 06/22] rcu: Rename rcu_irq_{enter,exit}_irqson() Peter Zijlstra
2020-02-19 16:38 ` Paul E. McKenney
2020-02-19 14:47 ` [PATCH v3 07/22] rcu: Mark rcu_dynticks_curr_cpu_in_eqs() inline Peter Zijlstra
2020-02-19 16:39 ` Paul E. McKenney
2020-02-19 17:19 ` Steven Rostedt
2020-02-19 14:47 ` [PATCH v3 08/22] rcu,tracing: Create trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-19 15:49 ` Steven Rostedt
2020-02-19 15:58 ` Peter Zijlstra
2020-02-19 16:15 ` Steven Rostedt
2020-02-19 16:35 ` Peter Zijlstra
2020-02-19 16:44 ` Paul E. McKenney
2020-02-20 10:34 ` Peter Zijlstra
2020-02-20 13:58 ` Paul E. McKenney
2020-02-19 14:47 ` [PATCH v3 09/22] sched,rcu,tracing: Avoid tracing before in_nmi() is correct Peter Zijlstra
2020-02-19 15:50 ` Steven Rostedt
2020-02-19 15:50 ` Steven Rostedt
2020-02-19 14:47 ` [PATCH v3 10/22] x86,tracing: Add comments to do_nmi() Peter Zijlstra
2020-02-19 15:51 ` Steven Rostedt
2020-02-19 14:47 ` [PATCH v3 11/22] perf,tracing: Prepare the perf-trace interface for RCU changes Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 12/22] tracing: Employ trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-19 15:52 ` Steven Rostedt
2020-02-19 14:47 ` [PATCH v3 13/22] tracing: Remove regular RCU context for _rcuidle tracepoints (again) Peter Zijlstra
2020-02-19 15:53 ` Steven Rostedt
2020-02-19 16:43 ` Paul E. McKenney
2020-02-19 16:47 ` Peter Zijlstra
2020-02-19 17:05 ` Peter Zijlstra
2020-02-19 17:21 ` Steven Rostedt
2020-02-19 17:40 ` Paul E. McKenney
2020-02-19 18:00 ` Steven Rostedt
2020-02-19 19:05 ` Paul E. McKenney
2020-02-19 14:47 ` [PATCH v3 14/22] perf,tracing: Allow function tracing when !RCU Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 15/22] x86/int3: Ensure that poke_int3_handler() is not traced Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 16/22] locking/atomics, kcsan: Add KCSAN instrumentation Peter Zijlstra
2020-02-19 15:46 ` Steven Rostedt
2020-02-19 16:03 ` Peter Zijlstra
2020-02-19 16:50 ` Paul E. McKenney
2020-02-19 16:54 ` Peter Zijlstra
2020-02-19 17:36 ` Paul E. McKenney
2020-02-19 14:47 ` [PATCH v3 17/22] asm-generic/atomic: Use __always_inline for pure wrappers Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 18/22] asm-generic/atomic: Use __always_inline for fallback wrappers Peter Zijlstra
2020-02-19 16:55 ` Paul E. McKenney
2020-02-19 17:06 ` Peter Zijlstra
2020-02-19 17:35 ` Paul E. McKenney
2020-02-19 14:47 ` [PATCH v3 19/22] compiler: Simple READ/WRITE_ONCE() implementations Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 20/22] locking/atomics: Flip fallbacks and instrumentation Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 21/22] x86/int3: Avoid atomic instrumentation Peter Zijlstra
2020-02-19 14:47 ` [PATCH v3 22/22] x86/int3: Ensure that poke_int3_handler() is not sanitized Peter Zijlstra
2020-02-19 16:06 ` Dmitry Vyukov
2020-02-19 16:30 ` Peter Zijlstra
2020-02-19 16:51 ` Peter Zijlstra
2020-02-19 17:20 ` Peter Zijlstra
2020-02-20 10:37 ` Dmitry Vyukov
2020-02-20 12:06 ` Peter Zijlstra
2020-02-20 16:22 ` Dmitry Vyukov
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