linux-kernel - Re: [RFC] Make need_resched() return true when rcu_urgent

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: <20180719170953.GA17730@linux.vnet.ibm.com>
Date:   Thu, 19 Jul 2018 10:09:53 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Peter Zijlstra <peterz@...radead.org>, mhillenb@...zon.de,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>
Subject: Re: [RFC] Make need_resched() return true when rcu_urgent_qs
 requested

On Wed, Jul 18, 2018 at 09:37:12AM -0700, Paul E. McKenney wrote:
> On Wed, Jul 18, 2018 at 06:01:51PM +0200, David Woodhouse wrote:
> > On Wed, 2018-07-18 at 08:36 -0700, Paul E. McKenney wrote:
> > > And I finally did get some near misses from an earlier commit, so we
> > > should consider your patch to be officially off the hook.
> > 
> > Yay, I like it when it's not my fault. I'll redo it with the ifdef
> > CONFIG_NO_HZ_FULL.
> 
> Hey, I didn't say it wasn't your fault, only that it -officially- wasn't
> your fault.  ;-)

And I believe that I found my bug in this commit (lots more testing still
required, but the preponderance of evidence and all that):

2cc0c7f07143 ("rcu: Eliminate ->rcu_qs_ctr from the rcu_dynticks structure")

So it really isn't your fault.

Of course, the real reason for the lack of fault on your part will not
because I believe I found the bug elsewhere, but instead because I will
be dropping your patch (and mine as well) on Frederic's advice.  ;-)

							Thanx, Paul