linux-kernel - Re: RCU lockup in the SMP idle thread, help...

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120920141052.GA2449@linux.vnet.ibm.com>
Date:	Thu, 20 Sep 2012 07:10:52 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	linux-kernel@...r.kernel.org
Subject: Re: RCU lockup in the SMP idle thread, help...

On Thu, Sep 20, 2012 at 11:07:37AM +0200, Linus Walleij wrote:
> On Thu, Sep 20, 2012 at 2:03 AM, Paul E. McKenney
> <paulmck@...ux.vnet.ibm.com> wrote:
> 
> > In the meantime, a crude fallback is for the CPU that detected the stall
> > to trace the stack of the task running on the other CPU.  See below for
> > a crude (and untested) patch.
> 
> OK now I get this:
> 
>  INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1,
> t=29508 jiffies)
> Task dump for CPU 0:
> swapper/0       R running      0     0      0 0x00000000
> [<c02da614>] (__schedule+0x238/0x52c) from [<c000f238>] (default_idle+0x28/0x30)
> [<c000f238>] (default_idle+0x28/0x30) from [<ffffffff>] (0xffffffff)
> INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1,
> t=29851 jiffies)
> Task dump for CPU 0:
> swapper/0       R running      0     0      0 0x00000000
> [<c02da614>] (__schedule+0x238/0x52c) from [<c000f238>] (default_idle+0x28/0x30)
> [<c000f238>] (default_idle+0x28/0x30) from [<ffffffff>] (0xffffffff)
> 
> So the swapper thread is the culprit?
> Hm, I'm not very smart with this no...

Can we convince ARM to dump the stack of the swapper thread in this case?
That would get us valuable information.

							Thanx, Paul

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/