From: Marc Zyngier <Marc.Zyngier@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Yong Zhang <yong.zhang0@gmail.com>, Ingo Molnar <mingo@elte.hu>,
Frank Rowand <frank.rowand@am.sony.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM
Date: Thu, 26 May 2011 15:56:21 +0100 [thread overview]
Message-ID: <1306421781.27474.224.camel@e102391-lin.cambridge.arm.com> (raw)
In-Reply-To: <1306412511.1200.90.camel@twins>
On Thu, 2011-05-26 at 14:21 +0200, Peter Zijlstra wrote:
> On Thu, 2011-05-26 at 13:32 +0200, Peter Zijlstra wrote:
> >
> > The bad news is of course that I've got a little more head-scratching to
> > do, will keep you informed.
>
> OK, that wasn't too hard.. (/me crosses fingers and prays Marc doesn't
> find more funnies ;-).
>
> Does the below cure all woes?
So far so good. The box just went through it's two first iterations of
kernel building without a sweat, carried on, and still feels snappy
enough.
Thanks for having fixed that quickly!
> ---
> Subject: sched: Fix ttwu() for __ARCH_WANT_INTERRUPTS_ON_CTXSW
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Thu May 26 14:21:33 CEST 2011
>
> Marc reported that e4a52bcb9 (sched: Remove rq->lock from the first
> half of ttwu()) broke his ARM-SMP machine. Now ARM is one of the few
> __ARCH_WANT_INTERRUPTS_ON_CTXSW users, so that exception in the ttwu()
> code was suspect.
>
> Yong found that the interrupt could hit hits after context_switch() changes
> current but before it clears p->on_cpu, if that interrupt were to
> attempt a wake-up of p we would indeed find ourselves spinning in IRQ
> context.
>
> Sort this by reverting to the old behaviour for this situation and
> perform a full remote wake-up.
>
> Cc: Frank Rowand <frank.rowand@am.sony.com>
> Cc: Yong Zhang <yong.zhang0@gmail.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Reported-by: Marc Zyngier <Marc.Zyngier@arm.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Reality is an implementation detail.
WARNING: multiple messages have this Message-ID (diff)
From: Marc.Zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM
Date: Thu, 26 May 2011 15:56:21 +0100 [thread overview]
Message-ID: <1306421781.27474.224.camel@e102391-lin.cambridge.arm.com> (raw)
In-Reply-To: <1306412511.1200.90.camel@twins>
On Thu, 2011-05-26 at 14:21 +0200, Peter Zijlstra wrote:
> On Thu, 2011-05-26 at 13:32 +0200, Peter Zijlstra wrote:
> >
> > The bad news is of course that I've got a little more head-scratching to
> > do, will keep you informed.
>
> OK, that wasn't too hard.. (/me crosses fingers and prays Marc doesn't
> find more funnies ;-).
>
> Does the below cure all woes?
So far so good. The box just went through it's two first iterations of
kernel building without a sweat, carried on, and still feels snappy
enough.
Thanks for having fixed that quickly!
> ---
> Subject: sched: Fix ttwu() for __ARCH_WANT_INTERRUPTS_ON_CTXSW
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Thu May 26 14:21:33 CEST 2011
>
> Marc reported that e4a52bcb9 (sched: Remove rq->lock from the first
> half of ttwu()) broke his ARM-SMP machine. Now ARM is one of the few
> __ARCH_WANT_INTERRUPTS_ON_CTXSW users, so that exception in the ttwu()
> code was suspect.
>
> Yong found that the interrupt could hit hits after context_switch() changes
> current but before it clears p->on_cpu, if that interrupt were to
> attempt a wake-up of p we would indeed find ourselves spinning in IRQ
> context.
>
> Sort this by reverting to the old behaviour for this situation and
> perform a full remote wake-up.
>
> Cc: Frank Rowand <frank.rowand@am.sony.com>
> Cc: Yong Zhang <yong.zhang0@gmail.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Reported-by: Marc Zyngier <Marc.Zyngier@arm.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
M.
--
Reality is an implementation detail.
next prev parent reply other threads:[~2011-05-26 14:55 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-24 18:13 [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM Marc Zyngier
2011-05-24 18:13 ` Marc Zyngier
2011-05-24 21:32 ` Peter Zijlstra
2011-05-24 21:32 ` Peter Zijlstra
2011-05-24 21:39 ` Ingo Molnar
2011-05-24 21:39 ` Ingo Molnar
2011-05-25 12:23 ` Marc Zyngier
2011-05-25 12:23 ` Marc Zyngier
2011-05-25 17:08 ` Peter Zijlstra
2011-05-25 17:08 ` Peter Zijlstra
2011-05-25 21:15 ` Peter Zijlstra
2011-05-25 21:15 ` Peter Zijlstra
2011-05-26 7:29 ` Yong Zhang
2011-05-26 7:29 ` Yong Zhang
2011-05-26 10:32 ` Peter Zijlstra
2011-05-26 10:32 ` Peter Zijlstra
2011-05-26 11:02 ` Marc Zyngier
2011-05-26 11:02 ` Marc Zyngier
2011-05-26 11:32 ` Peter Zijlstra
2011-05-26 11:32 ` Peter Zijlstra
2011-05-26 12:21 ` Peter Zijlstra
2011-05-26 12:21 ` Peter Zijlstra
2011-05-26 12:26 ` Ingo Molnar
2011-05-26 12:26 ` Ingo Molnar
2011-05-26 12:31 ` Russell King - ARM Linux
2011-05-26 12:31 ` Russell King - ARM Linux
2011-05-26 12:37 ` Peter Zijlstra
2011-05-26 12:37 ` Peter Zijlstra
2011-05-26 12:50 ` Ingo Molnar
2011-05-26 12:50 ` Ingo Molnar
2011-05-26 13:36 ` Russell King - ARM Linux
2011-05-26 13:36 ` Russell King - ARM Linux
2011-05-26 14:45 ` Catalin Marinas
2011-05-26 14:45 ` Catalin Marinas
2011-05-27 12:06 ` Ingo Molnar
2011-05-27 12:06 ` Ingo Molnar
2011-05-27 17:55 ` Russell King - ARM Linux
2011-05-27 17:55 ` Russell King - ARM Linux
2011-05-27 19:41 ` Nicolas Pitre
2011-05-27 19:41 ` Nicolas Pitre
2011-05-27 20:52 ` Russell King - ARM Linux
2011-05-27 20:52 ` Russell King - ARM Linux
2011-05-28 13:13 ` Peter Zijlstra
2011-05-28 13:13 ` Peter Zijlstra
2011-05-31 11:08 ` Michal Simek
2011-05-31 11:08 ` Michal Simek
2011-05-31 13:22 ` Peter Zijlstra
2011-05-31 13:22 ` Peter Zijlstra
2011-05-31 13:37 ` Michal Simek
2011-05-31 13:37 ` Michal Simek
2011-05-31 13:52 ` Peter Zijlstra
2011-05-31 13:52 ` Peter Zijlstra
2011-05-31 14:08 ` Michal Simek
2011-05-31 14:08 ` Michal Simek
2011-05-31 14:29 ` Peter Zijlstra
2011-05-31 14:29 ` Peter Zijlstra
2011-05-29 10:21 ` Catalin Marinas
2011-05-29 10:21 ` Catalin Marinas
2011-05-29 10:26 ` Russell King - ARM Linux
2011-05-29 10:26 ` Russell King - ARM Linux
2011-05-29 12:01 ` Catalin Marinas
2011-05-29 12:01 ` Catalin Marinas
2011-05-29 13:19 ` Russell King - ARM Linux
2011-05-29 13:19 ` Russell King - ARM Linux
2011-05-29 21:21 ` Catalin Marinas
2011-05-29 21:21 ` Catalin Marinas
2011-05-29 9:51 ` Catalin Marinas
2011-05-29 9:51 ` Catalin Marinas
2011-06-06 10:29 ` Pavel Machek
2011-06-06 10:29 ` Pavel Machek
2011-05-26 14:56 ` Marc Zyngier [this message]
2011-05-26 14:56 ` Marc Zyngier
2011-05-26 15:45 ` Oleg Nesterov
2011-05-26 15:45 ` Oleg Nesterov
2011-05-26 15:59 ` Peter Zijlstra
2011-05-26 15:59 ` Peter Zijlstra
2011-05-26 16:09 ` Peter Zijlstra
2011-05-26 16:09 ` Peter Zijlstra
2011-05-26 16:20 ` Marc Zyngier
2011-05-26 16:20 ` Marc Zyngier
2011-05-26 16:32 ` Peter Zijlstra
2011-05-26 16:32 ` Peter Zijlstra
2011-05-27 8:01 ` Marc Zyngier
2011-05-27 8:01 ` Marc Zyngier
2011-05-26 16:22 ` Marc Zyngier
2011-05-26 16:22 ` Marc Zyngier
2011-05-26 17:04 ` Oleg Nesterov
2011-05-26 17:04 ` Oleg Nesterov
2011-05-26 17:17 ` Peter Zijlstra
2011-05-26 17:17 ` Peter Zijlstra
2011-05-26 17:23 ` Peter Zijlstra
2011-05-26 17:23 ` Peter Zijlstra
2011-05-26 17:49 ` Oleg Nesterov
2011-05-26 17:49 ` Oleg Nesterov
2011-05-27 7:01 ` Yong Zhang
2011-05-27 7:01 ` Yong Zhang
2011-05-27 15:23 ` Santosh Shilimkar
2011-05-27 15:23 ` Santosh Shilimkar
2011-05-27 15:29 ` Marc Zyngier
2011-05-27 15:29 ` Marc Zyngier
2011-05-27 15:30 ` Santosh Shilimkar
2011-05-27 15:30 ` Santosh Shilimkar
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