linux-kernel - Re: sched: serial port lockdep warning when offlining CPUs

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]

Date:   Thu, 28 Sep 2017 14:05:32 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sasha Levin <levinsasha928@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...e.hu>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        "pmladek@...e.com" <pmladek@...e.com>,
        "sergey.senozhatsky@...il.com" <sergey.senozhatsky@...il.com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>
Subject: Re: sched: serial port lockdep warning when offlining CPUs

(please linewrap normal text at 72 chars)

On Thu, Sep 28, 2017 at 11:45:30AM +0000, Levin, Alexander (Sasha Levin) wrote:
> Okay, that seems to have delt with the callbacks supressed issue.
> 
> I also seem to be hitting it as a result of the scheduler triggering a
> WARN, where print_stack_trace(), for example, just uses printk().
> 
> Now I'm not sure what's your approach here, do we keep converting
> printk to printk_deferred one by one until we whacked every mole?

Nah.. WARN's _should_ not trigger. If they do we fix that.

Getting a lockdep splat after a WARN is something I can live with.

And you really don't want that deferred nonsense for WARNs, because that
means you'll risk not over getting the output.