linux-kernel - Re: [PATCH 2/2] sched: mark PRINTK_DEFERRED_CONTEXT_MASK in _

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: <20200928080022.GD2611@hirez.programming.kicks-ass.net>
Date:   Mon, 28 Sep 2020 10:00:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Chengming Zhou <zhouchengming@...edance.com>,
        linux-kernel@...r.kernel.org, pmladek@...e.com,
        sergey.senozhatsky@...il.com, rostedt@...dmis.org,
        mingo@...hat.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        bsegall@...gle.com, mgorman@...e.de, songmuchun@...edance.com
Subject: Re: [PATCH 2/2] sched: mark PRINTK_DEFERRED_CONTEXT_MASK in
 __schedule()

On Mon, Sep 28, 2020 at 12:52:44AM -0700, Joe Perches wrote:
> On Mon, 2020-09-28 at 09:32 +0200, Peter Zijlstra wrote:
> > On Mon, Sep 28, 2020 at 12:11:30AM +0800, Chengming Zhou wrote:
> > > The WARN_ON/WARN_ON_ONCE with rq lock held in __schedule() should be
> > > deferred by marking the PRINTK_DEFERRED_CONTEXT_MASK, or will cause
> > > deadlock on rq lock in the printk path.
> []
> > NAK printk_deferred is an abomination, kill that.
> 
> Didn't you introduce it?
> Should you be complaining to yourself?

Yeah. I should've hacked around it then I suppose. Still, no reason to
proliferate that crap. Afaik the new printk should be able to deal with
this at some point.

The thing we're not going to do it add a cache-miss to schedule just
because.