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 12:02:39 +0100 [thread overview]
Message-ID: <1306407759.27474.207.camel@e102391-lin.cambridge.arm.com> (raw)
In-Reply-To: <1306405979.1200.63.camel@twins>
On Thu, 2011-05-26 at 12:32 +0200, Peter Zijlstra wrote:
> On Thu, 2011-05-26 at 15:29 +0800, Yong Zhang wrote:
> > > Figuring out why the existing condition failed
> >
> > Seems 'current' will change before/after switch_to since it's derived from
> > sp register.
> > So that means if interrupt come before we switch sp, 'p == current' will
> > catch it, but if interrupt comes after we switch sp, we will lose a wake up.
>
> Well, loosing a wakeup isn't the problem here (although it would be a
> problem), the immediate problem is that we're getting stuck
> (life-locked) in that while (p->on_cpu) loop.
>
> But yes, I think that explains it, if the interrupts hits
> context_switch() after current was changed but before clearing
> p->on_cpu, we would life-lock in interrupt context.
>
> Now we could of course go add in_interrupt() checks there, but that
> would make this already fragile path more interesting, so I think I'll
> stick with the proposed patch -- again provided it actually works.
>
> Marc, any word on that?
The box is currently building kernels in a loop (using -j64...). So far,
so good. Oh, and that fixed the load-average thing as well.
Oh wait (my turn...):
INFO: task gcc:10030 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
One of my ssh sessions is locking up periodically, and it generally
feels a bit sluggish.
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 12:02:39 +0100 [thread overview]
Message-ID: <1306407759.27474.207.camel@e102391-lin.cambridge.arm.com> (raw)
In-Reply-To: <1306405979.1200.63.camel@twins>
On Thu, 2011-05-26 at 12:32 +0200, Peter Zijlstra wrote:
> On Thu, 2011-05-26 at 15:29 +0800, Yong Zhang wrote:
> > > Figuring out why the existing condition failed
> >
> > Seems 'current' will change before/after switch_to since it's derived from
> > sp register.
> > So that means if interrupt come before we switch sp, 'p == current' will
> > catch it, but if interrupt comes after we switch sp, we will lose a wake up.
>
> Well, loosing a wakeup isn't the problem here (although it would be a
> problem), the immediate problem is that we're getting stuck
> (life-locked) in that while (p->on_cpu) loop.
>
> But yes, I think that explains it, if the interrupts hits
> context_switch() after current was changed but before clearing
> p->on_cpu, we would life-lock in interrupt context.
>
> Now we could of course go add in_interrupt() checks there, but that
> would make this already fragile path more interesting, so I think I'll
> stick with the proposed patch -- again provided it actually works.
>
> Marc, any word on that?
The box is currently building kernels in a loop (using -j64...). So far,
so good. Oh, and that fixed the load-average thing as well.
Oh wait (my turn...):
INFO: task gcc:10030 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
One of my ssh sessions is locking up periodically, and it generally
feels a bit sluggish.
M.
--
Reality is an implementation detail.
next prev parent reply other threads:[~2011-05-26 11:02 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 [this message]
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
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
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=1306407759.27474.207.camel@e102391-lin.cambridge.arm.com \
--to=marc.zyngier@arm.com \
--cc=frank.rowand@am.sony.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=yong.zhang0@gmail.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.