linux-kernel - Re: rcu_sched stall while waiting in csd_lock

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: <20170803083205.x4v3ubk4jalff3tu@hirez.programming.kicks-ass.net>
Date:   Thu, 3 Aug 2017 10:32:05 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Pratyush Anand <panand@...hat.com>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Will Deacon <will.deacon@....com>,
        open list <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: rcu_sched stall while waiting in csd_lock_wait()

On Thu, Aug 03, 2017 at 09:26:06AM +0530, Pratyush Anand wrote:
> Hi Peter,
> 
> On Wednesday 02 August 2017 01:44 PM, Peter Zijlstra wrote:
> > On Wed, Aug 02, 2017 at 09:01:19AM +0530, Pratyush Anand wrote:
> > > Hi,
> > > 
> > > I am observing following rcu_sched stall while executing `perf record -a  --
> > > sleep 1` with one of the arm64 platform. It looks like that stalled cpu was
> > > waiting in csd_lock_wait() from where it never came out,and so the stall.
> > > Any help/pointer for further debugging would be very helpful. Problem also
> > > reproduced with 4.13.0-rc3.
> > 
> > I'm sitting on this patch:
> > 
> >    https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?h=locking/core&id=15377ef4fe0c86eb7fa1099575b2e86357d99e42
> > 
> > please give that a spin.
> 
> Thanks for the pointer.

Seems like my brain misfired in any case. That's the OSQ lock not the
CSD one ;-) Let me go stare at your traces with hopefully more
wakefulness.