linux-kernel - Re: Second soft lockup regression in yesterday's sched.git merge

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] [day] [month] [year] [list]

Message-Id: <1208933499.7115.324.camel@twins>
Date:	Wed, 23 Apr 2008 08:51:39 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	David Miller <davem@...emloft.net>
Cc:	mingo@...e.hu, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	guichaz@...oo.fr
Subject: Re: Second soft lockup regression in yesterday's sched.git merge

On Tue, 2008-04-22 at 23:39 -0700, David Miller wrote:
> Two changets after the buggy cpu_clock() changes, we have:
> 
> commit 15934a37324f32e0fda633dc7984a671ea81cd75
> Author: Guillaume Chazarain <guichaz@...oo.fr>
> Date:   Sat Apr 19 19:44:57 2008 +0200
> 
>     sched: fix rq->clock overflows detection with CONFIG_NO_HZ
>     
>     When using CONFIG_NO_HZ, rq->tick_timestamp is not updated every TICK_NSEC.
>     We check that the number of skipped ticks matches the clock jump seen in
>     __update_rq_clock().
>     
>     Signed-off-by: Guillaume Chazarain <guichaz@...oo.fr>
>     Signed-off-by: Ingo Molnar <mingo@...e.hu>
> 
> Which also causes softlockup warnings on my Niagara systems.
> 
> Note this is with the cpu_clock() change reverted, and the
> usual test case kernel build after a delay:
> 
> 	sleep 10m; time make -j64 >build.log 2>&1; make -j64 image

The effect of this one is that it should properly account idle time in
rq->clock when waking from nohz.

This 'extra' idle time would then propagate through cpu_clock() into the
softlockup code.

Could it be we touch the soft watchdog before we correct all these idle
times?

--
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/