From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: paulmck@linux.vnet.ibm.com, Fengguang Wu <fengguang.wu@intel.com>,
LKP <lkp@01.org>,
linux-kernel@vger.kernel.org,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
linux-arm-kernel@lists.infradead.org,
Arnd Bergmann <arnd@arndb.de>, MarkRutland <mark.rutland@arm.com>
Subject: Re: [rcu] [ INFO: suspicious RCU usage. ]
Date: Wed, 4 Feb 2015 13:00:18 +0000 [thread overview]
Message-ID: <20150204130018.GG8656@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1423049947.19547.6.camel@AMDC1943>
On Wed, Feb 04, 2015 at 12:39:07PM +0100, Krzysztof Kozlowski wrote:
> +Cc some ARM people
I wish that people would CC this list with problems seen on ARM. I'm
minded to just ignore this message because of this in the hope that by
doing so, people will learn something...
> > Another thing I could do would be to have an arch-specific Kconfig
> > variable that made ARM responsible for informing RCU that the CPU
> > was departing, which would allow a call to as follows to be placed
> > immediately after the complete():
> >
> > rcu_cpu_notify(NULL, CPU_DYING_IDLE, (void *)(long)smp_processor_id());
> >
> > Note: This absolutely requires that the rcu_cpu_notify() -always-
> > be allowed to execute!!! This will not work if there is -any- possibility
> > of __cpu_die() powering off the outgoing CPU before the call to
> > rcu_cpu_notify() returns.
Exactly, so that's not going to be possible. The completion at that
point marks the point at which power _could_ be removed from the CPU
going down.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [rcu] [ INFO: suspicious RCU usage. ]
Date: Wed, 4 Feb 2015 13:00:18 +0000 [thread overview]
Message-ID: <20150204130018.GG8656@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1423049947.19547.6.camel@AMDC1943>
On Wed, Feb 04, 2015 at 12:39:07PM +0100, Krzysztof Kozlowski wrote:
> +Cc some ARM people
I wish that people would CC this list with problems seen on ARM. I'm
minded to just ignore this message because of this in the hope that by
doing so, people will learn something...
> > Another thing I could do would be to have an arch-specific Kconfig
> > variable that made ARM responsible for informing RCU that the CPU
> > was departing, which would allow a call to as follows to be placed
> > immediately after the complete():
> >
> > rcu_cpu_notify(NULL, CPU_DYING_IDLE, (void *)(long)smp_processor_id());
> >
> > Note: This absolutely requires that the rcu_cpu_notify() -always-
> > be allowed to execute!!! This will not work if there is -any- possibility
> > of __cpu_die() powering off the outgoing CPU before the call to
> > rcu_cpu_notify() returns.
Exactly, so that's not going to be possible. The completion at that
point marks the point at which power _could_ be removed from the CPU
going down.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: lkp@lists.01.org
Subject: Re: [rcu] [ INFO: suspicious RCU usage. ]
Date: Wed, 04 Feb 2015 13:00:18 +0000 [thread overview]
Message-ID: <20150204130018.GG8656@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <1423049947.19547.6.camel@AMDC1943>
[-- Attachment #1: Type: text/plain, Size: 1140 bytes --]
On Wed, Feb 04, 2015 at 12:39:07PM +0100, Krzysztof Kozlowski wrote:
> +Cc some ARM people
I wish that people would CC this list with problems seen on ARM. I'm
minded to just ignore this message because of this in the hope that by
doing so, people will learn something...
> > Another thing I could do would be to have an arch-specific Kconfig
> > variable that made ARM responsible for informing RCU that the CPU
> > was departing, which would allow a call to as follows to be placed
> > immediately after the complete():
> >
> > rcu_cpu_notify(NULL, CPU_DYING_IDLE, (void *)(long)smp_processor_id());
> >
> > Note: This absolutely requires that the rcu_cpu_notify() -always-
> > be allowed to execute!!! This will not work if there is -any- possibility
> > of __cpu_die() powering off the outgoing CPU before the call to
> > rcu_cpu_notify() returns.
Exactly, so that's not going to be possible. The completion at that
point marks the point at which power _could_ be removed from the CPU
going down.
--
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2015-02-04 13:00 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-01 2:59 [rcu] [ INFO: suspicious RCU usage. ] Fengguang Wu
2015-02-01 2:59 ` Fengguang Wu
2015-02-03 10:01 ` Krzysztof Kozlowski
2015-02-03 10:01 ` Krzysztof Kozlowski
2015-02-03 16:27 ` Paul E. McKenney
2015-02-03 16:27 ` Paul E. McKenney
2015-02-04 11:39 ` Krzysztof Kozlowski
2015-02-04 11:39 ` Krzysztof Kozlowski
2015-02-04 11:39 ` Krzysztof Kozlowski
2015-02-04 13:00 ` Russell King - ARM Linux [this message]
2015-02-04 13:00 ` Russell King - ARM Linux
2015-02-04 13:00 ` Russell King - ARM Linux
2015-02-04 13:14 ` Paul E. McKenney
2015-02-04 13:14 ` Paul E. McKenney
2015-02-04 13:14 ` Paul E. McKenney
2015-02-04 14:16 ` Krzysztof Kozlowski
2015-02-04 14:16 ` Krzysztof Kozlowski
2015-02-04 14:16 ` Krzysztof Kozlowski
2015-02-04 15:10 ` Paul E. McKenney
2015-02-04 15:10 ` Paul E. McKenney
2015-02-04 15:10 ` Paul E. McKenney
2015-02-04 15:16 ` Russell King - ARM Linux
2015-02-04 15:16 ` Russell King - ARM Linux
2015-02-04 15:16 ` Russell King - ARM Linux
2015-02-04 15:46 ` Paul E. McKenney
2015-02-04 15:46 ` Paul E. McKenney
2015-02-04 15:46 ` Paul E. McKenney
2015-02-04 15:22 ` Krzysztof Kozlowski
2015-02-04 15:22 ` Krzysztof Kozlowski
2015-02-04 15:22 ` Krzysztof Kozlowski
2015-02-04 15:56 ` Paul E. McKenney
2015-02-04 15:56 ` Paul E. McKenney
2015-02-04 15:56 ` Paul E. McKenney
2015-02-04 16:10 ` Krzysztof Kozlowski
2015-02-04 16:10 ` Krzysztof Kozlowski
2015-02-04 16:10 ` Krzysztof Kozlowski
2015-02-04 16:28 ` Paul E. McKenney
2015-02-04 16:28 ` Paul E. McKenney
2015-02-04 16:28 ` Paul E. McKenney
2015-02-04 16:43 ` Krzysztof Kozlowski
2015-02-04 16:43 ` Krzysztof Kozlowski
2015-02-04 16:43 ` Krzysztof Kozlowski
2015-02-04 13:13 ` Paul E. McKenney
2015-02-04 13:13 ` Paul E. McKenney
2015-02-04 13:13 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150204130018.GG8656@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=arnd@arndb.de \
--cc=b.zolnierkie@samsung.com \
--cc=fengguang.wu@intel.com \
--cc=k.kozlowski@samsung.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@01.org \
--cc=mark.rutland@arm.com \
--cc=paulmck@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.