linux-kernel - Re: [RFC PATCH 09/16] sched/fair: core wide cfs task priority comparison(Internet mail)

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: <CAPJCdBk6gWwEkPGTr3=kCZ9QXboUfPFDPCA1oRgSg1cD_kHUrQ@mail.gmail.com>
Date:   Fri, 24 Jul 2020 20:08:43 +0800
From:   Jiang Biao <benbjiang@...il.com>
To:     Aaron Lu <aaron.lwe@...il.com>
Cc:     benbjiang(蒋彪) <benbjiang@...cent.com>,
        Vineeth Remanan Pillai <vpillai@...italocean.com>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "pjt@...gle.com" <pjt@...gle.com>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "subhra.mazumdar@...cle.com" <subhra.mazumdar@...cle.com>,
        "fweisbec@...il.com" <fweisbec@...il.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "kerrnel@...gle.com" <kerrnel@...gle.com>,
        Phil Auld <pauld@...hat.com>,
        Aubrey Li <aubrey.intel@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joel Fernandes <joelaf@...gle.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "vineethrp@...il.com" <vineethrp@...il.com>,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Aaron Lu <ziqian.lzq@...fin.com>
Subject: Re: [RFC PATCH 09/16] sched/fair: core wide cfs task priority
 comparison(Internet mail)

On Fri, 24 Jul 2020 at 15:17, Aaron Lu <aaron.lwe@...il.com> wrote:
>
> On Wed, Jul 22, 2020 at 12:23:44AM +0000, benbjiang(蒋彪) wrote:
> >
> >
> > > +/*
> > > + * This function takes care of adjusting the min_vruntime of siblings of
> > > + * a core during coresched enable/disable.
> > > + * This is called in stop machine context so no need to take the rq lock.
> > Hi,
> >
> > IMHO, it seems that stop machine context cannot guarantee race free. The param *cpu* maybe not *this_cpu*, rq lock should be taken even in stop machine context, and irq should be disabled too, to avoid potential races with other contexts.
> >
>
> In stop machine context, all CPUs except the active ones are spinning
> with irq disabled and in this invocation of stop_machine(), only one
> CPU is active so I don't think race is possible.
You're right, stop_machine provides much more protection than stop_*_cpu.
Thanks for the explanation.

Regards,
Jiang