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From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: tglx@linutronix.de, luto@amacapital.net,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	Lai Jiangshan <laijs@linux.alibaba.com>,
	sean.j.christopherson@intel.com, andrew.cooper3@citrix.com,
	daniel.thompson@linaro.org, a.darwish@linutronix.de,
	bigeasy@linutronix.de
Subject: Re: [PATCH 13/14] lockdep: Prepare for NMI IRQ state tracking
Date: Sat, 30 May 2020 00:33:54 +0200
Message-ID: <20200529223354.GX2483@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20200529222505.GW2483@worktop.programming.kicks-ass.net>

On Sat, May 30, 2020 at 12:25:05AM +0200, Peter Zijlstra wrote:
> On Fri, May 29, 2020 at 06:14:01PM -0400, Steven Rostedt wrote:
> > On Fri, 29 May 2020 23:27:41 +0200
> > Peter Zijlstra <peterz@infradead.org> wrote:
> > 
> > > There is no reason not to always, accurately, track IRQ state.
> > > 
> > > This change also makes IRQ state tracking ignore lockdep_off().
> > > 
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > ---
> > >  kernel/locking/lockdep.c |   33 ++++++++++++++++++++++++++++++---
> > >  1 file changed, 30 insertions(+), 3 deletions(-)
> > > 
> > > --- a/kernel/locking/lockdep.c
> > > +++ b/kernel/locking/lockdep.c
> > > @@ -3646,7 +3646,13 @@ static void __trace_hardirqs_on_caller(v
> > >   */
> > >  void lockdep_hardirqs_on_prepare(unsigned long ip)
> > >  {
> > > -	if (unlikely(!debug_locks || current->lockdep_recursion))
> > 
> > Why remove the check for debug_locks? Isn't that there to disable
> > everything at once to prevent more warnings to be printed?
> 
> Yeah, maybe. I was thinking we could keep IRQ state running. But you're
> right, if we mess up the IRQ state itself this might generate a wee
> mess.

That is, mostly the IRQ state recovers when we mess up. It's only when
we then trigger more fail that we crash and burn, and that will likely
already give more warnings.

But I can put the debug_locks check back.

  parent reply index

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29 21:27 [PATCH 00/14] x86/entry: disallow #DB more and x86/entry lockdep/nmi Peter Zijlstra
2020-05-29 21:27 ` [PATCH 01/14] x86/hw_breakpoint: Add within_area() to check data breakpoints Peter Zijlstra
2020-05-29 21:27 ` [PATCH 02/14] x86/hw_breakpoint: Prevent data breakpoints on direct GDT Peter Zijlstra
2020-05-30 12:45   ` Andrew Cooper
2020-05-30 15:15     ` Lai Jiangshan
2020-05-29 21:27 ` [PATCH 03/14] x86/hw_breakpoint: Prevent data breakpoints on per_cpu cpu_tss_rw Peter Zijlstra
2020-05-29 21:27 ` [PATCH 04/14] x86/hw_breakpoint: Prevent data breakpoints on user_pcid_flush_mask Peter Zijlstra
2020-05-29 21:27 ` [PATCH 05/14] x86/entry: Introduce local_db_{save,restore}() Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 06/14] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 07/14] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 08/14] x86/entry: Optimize local_db_save() for virt Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03  1:17   ` [PATCH 08/14] " Sean Christopherson
2020-05-29 21:27 ` [PATCH 09/14] x86/entry: Remove debug IDT frobbing Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 10/14] x86/entry: Remove DBn stacks Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 11/14] x86/entry: Clarify irq_{enter,exit}_rcu() Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-02 14:42   ` [PATCH 11/14] " Qian Cai
2020-06-02 15:05     ` Peter Zijlstra
2020-06-02 18:47       ` Qian Cai
2020-06-03 17:50       ` [tip: x86/entry] x86/entry: Use __irq_exit_rcu() in irq_exit() tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 12/14] x86/entry: Rename trace_hardirqs_off_prepare() Peter Zijlstra
2020-05-30  9:57   ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 13/14] lockdep: Prepare for NMI IRQ state tracking Peter Zijlstra
2020-05-29 22:14   ` Steven Rostedt
2020-05-29 22:25     ` Peter Zijlstra
2020-05-29 22:28       ` Steven Rostedt
2020-05-29 22:33       ` Peter Zijlstra [this message]
2020-06-02 20:00       ` Peter Zijlstra
2020-05-29 21:27 ` [PATCH 14/14] x86/entry: Fix NMI vs " Peter Zijlstra

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