linux-kernel - Re: [PATCH 00/11] rcu: Make rcu_core() safe in PREEMPT

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: <87fstkmybc.mognet@arm.com>
Date:   Fri, 01 Oct 2021 18:47:51 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     Frederic Weisbecker <frederic@...nel.org>,
        "Paul E . McKenney" <paulmck@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Boqun Feng <boqun.feng@...il.com>,
        Neeraj Upadhyay <neeraju@...eaurora.org>,
        Josh Triplett <josh@...htriplett.org>,
        Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org
Subject: Re: [PATCH 00/11] rcu: Make rcu_core() safe in PREEMPT_RT with NOCB + a few other fixes

On 30/09/21 00:10, Frederic Weisbecker wrote:
> PREEMPT_RT has made rcu_core() preemptible, making it unsafe against
> concurrent NOCB (de-)offloading.
>
> Thomas suggested to drop the local_lock() based solution and simply
> check the offloaded state while context looks safe but that's not
> enough. Here is a bit of rework.
>
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
>       rcu/rt
>
> HEAD: aac1c58961446c731f2e989bd822ca1fd2659bad
>
> Thanks,
>       Frederic

FWIW I've had RCU torture with NOCB toggling running for half a day on my
Arm Juno and nothing to report. I still need to rebase this on an -rt tree
and give it a spin with CONFIG_PREEMPT_RT.