linux-kernel - Re: [PATCH v6 3/5] sched: Enforce user requested affinity

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: <Yw8n/Ef1NWnwmHYW@hirez.programming.kicks-ass.net>
Date:   Wed, 31 Aug 2022 11:21:00 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Lai Jiangshan <jiangshanlai@...il.com>
Subject: Re: [PATCH v6 3/5] sched: Enforce user requested affinity

On Wed, Aug 31, 2022 at 11:18:22AM +0200, Peter Zijlstra wrote:
> On Thu, Aug 25, 2022 at 09:01:17PM -0400, Waiman Long wrote:
> 
> > @@ -9352,6 +9381,11 @@ int sched_cpu_activate(unsigned int cpu)
> >  		sched_update_numa(cpu, true);
> >  		sched_domains_numa_masks_set(cpu);
> >  		cpuset_cpu_active();
> > +		/*
> > +		 * Preallocated scratch cpumask
> > +		 */
> > +		if (!rq->scratch_mask)
> > +			rq->scratch_mask = kmalloc(cpumask_size(), GFP_KERNEL);
> >  	}
> 
> this is too late; I think you'll have to add a sched_cpu_prepare() and
> simply fail the cpu-up when the allocation fails.

Alternatively, waste some more memory and add yet another per-cpu
cpumask.