linux-kernel - Re: [RESEND PATCH] sched: restore the behavior of put_task

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: <20250811110501.nTDNkPnM@linutronix.de>
Date: Mon, 11 Aug 2025 13:05:01 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Oleg Nesterov <oleg@...hat.com>
Cc: "Luis Claudio R. Goncalves" <lgoncalv@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Clark Williams <clrkwllms@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>, Tejun Heo <tj@...nel.org>,
	David Vernet <dvernet@...a.com>, Barret Rhoden <brho@...gle.com>,
	Josh Don <joshdon@...gle.com>, Crystal Wood <crwood@...hat.com>,
	linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev,
	Juri Lelli <juri.lelli@...hat.com>, Ben Segall <bsegall@...gle.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Ingo Molnar <mingo@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Wander Lairson Costa <wander@...hat.com>
Subject: Re: [RESEND PATCH] sched: restore the behavior of put_task_struct()
 for non-rt

On 2025-08-11 12:40:34 [+0200], Oleg Nesterov wrote:
> On 08/11, Sebastian Andrzej Siewior wrote:
> >
> > I don't want to drag this but this comment is obvious for anyone who is
> > fluent in C. It is just a statement with no explanation.
> > An important note would be that the atomic context restriction only
> > apply to PREEMPT_RT and therefore we have this context override for
> > lockdep below. The other question would be why don't we do this
> > unconditionally regardless of PREEMPT_RT. The only reason I could find
> > is that releasing the task here from the "exit path" makes the vmap
> > stack "earlier" available for reuse.
> 
> Sorry, could you clarify your "other" question?
> 
> What exactly do you think we could do regardless of PREEMPT_RT?

Do what we do now and have one free path for task_struct regardless if
PREEMPT_RT is enabled or not. The one via RCU which delays the freeing
until after the grace period.

> Oleg.

Sebastian