linux-kernel - Re: [PATCH v2 7/9] sched: define TIF_ALLOW

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <63d6ddfa-16ca-4c19-b542-a95f27d72f96@paulmck-laptop>
Date:   Wed, 18 Oct 2023 16:25:56 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ankur Arora <ankur.a.arora@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        akpm@...ux-foundation.org, luto@...nel.org, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        willy@...radead.org, mgorman@...e.de, rostedt@...dmis.org,
        jon.grimm@....com, bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        jgross@...e.com, andrew.cooper3@...rix.com,
        Frederic Weisbecker <fweisbec@...il.com>, urezki@...il.com
Subject: Re: [PATCH v2 7/9] sched: define TIF_ALLOW_RESCHED

On Thu, Oct 19, 2023 at 12:53:05AM +0200, Thomas Gleixner wrote:
> On Wed, Oct 18 2023 at 10:51, Paul E. McKenney wrote:
> > On Wed, Oct 18, 2023 at 05:09:46AM -0700, Ankur Arora wrote:
> 
> Can you folks please trim your replies. It's annoying to scroll
> through hundreds of quoted lines to figure out that nothing is there.
> 
> >>  This probably allows for more configuration flexibility across archs?
> >>  Would allow for TREE_RCU=y, for instance. That said, so far I've only
> >>  been working with PREEMPT_RCU=y.)
> >
> > Then this is a bug that needs to be fixed.  We need a way to make
> > RCU readers non-preemptible.
> 
> Why?

So that we don't get tail latencies from preempted RCU readers that
result in memory-usage spikes on systems that have good and sufficient
quantities of memory, but which do not have enough memory to tolerate
readers being preempted.

							Thanx, Paul