From: peterz@infradead.org
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, Ingo Molnar <mingo@redhat.com>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state
Date: Sun, 26 Jul 2020 13:59:44 +0200 [thread overview]
Message-ID: <20200726115944.GB119549@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1595735694.b784cvipam.astroid@bobo.none>
On Sun, Jul 26, 2020 at 02:14:34PM +1000, Nicholas Piggin wrote:
> > Now, x86, and at least arm64 call nmi_enter() before
> > trace_hardirqs_off(), but AFAICT Power never did that, and that's part
> > of the problem. nmi_enter() does lockdep_off() and that _used_ to also
> > kill IRQ tracking.
>
> Power does do nmi_enter -- __perf_event_interrupt()
>
> nmi = perf_intr_is_nmi(regs);
> if (nmi)
> nmi_enter();
> else
> irq_enter();
That's _waaaay_ too late, you've done the trace_hardirqs_{off,on} in
arch/powerpc/kernel/exceptions-64e.S, you need to _first_ do nmi_enter()
and _then_ trace_hardirqs_off(), or rather, that's still broken, but
then we get into the details of entry ordering.
next prev parent reply other threads:[~2020-07-26 11:59 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-23 10:56 Nicholas Piggin
2020-07-23 10:56 ` [PATCH 2/2] lockdep: warn on redundant or incorrect irq state changes Nicholas Piggin
2020-07-24 2:57 ` kernel test robot
2020-08-04 10:00 ` Alexey Kardashevskiy
2020-07-23 11:40 ` [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state Peter Zijlstra
2020-07-23 13:11 ` Nicholas Piggin
2020-07-23 14:59 ` Peter Zijlstra
2020-07-23 16:20 ` Nicholas Piggin
2020-07-24 4:16 ` Alexey Kardashevskiy
2020-07-24 5:59 ` Nicholas Piggin
2020-07-26 7:40 ` Alexey Kardashevskiy
2020-07-24 6:16 ` Athira Rajeev
2020-07-24 2:19 ` kernel test robot
2020-07-24 3:15 ` kernel test robot
2020-07-25 20:26 ` Peter Zijlstra
2020-07-26 4:14 ` Nicholas Piggin
2020-07-26 11:59 ` peterz [this message]
2020-07-26 12:11 ` peterz
2020-07-28 11:22 ` Nicholas Piggin
2020-08-07 11:11 ` peterz
2020-08-12 8:18 ` Nicholas Piggin
2020-08-12 10:35 ` peterz
2020-08-18 7:22 ` Nicholas Piggin
2020-08-18 15:41 ` peterz
2020-08-18 23:54 ` Nicholas Piggin
2020-08-19 10:39 ` Alexey Kardashevskiy
2020-08-19 15:32 ` peterz
2020-08-19 15:39 ` peterz
2020-08-27 7:54 ` [tip: locking/core] lockdep: Only trace IRQ edges tip-bot2 for Nicholas Piggin
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