linux-kernel - Re: [PATCH v2 00/14] Introducing TIF_NOTIFY

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]

Date: Sat, 15 Jun 2024 03:42:56 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: K Prateek Nayak <kprateek.nayak@....com>, linux-kernel@...r.kernel.org,
	"Gautham R. Shenoy" <gautham.shenoy@....com>,
	Richard Henderson <richard.henderson@...aro.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Matt Turner <mattst88@...il.com>,
	Russell King <linux@...linux.org.uk>, Guo Ren <guoren@...nel.org>,
	Michal Simek <monstr@...str.eu>, Dinh Nguyen <dinguyen@...nel.org>,
	Jonas Bonn <jonas@...thpole.se>,
	Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
	Stafford Horne <shorne@...il.com>,
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
	Helge Deller <deller@....de>, Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>,
	Rich Felker <dalias@...c.org>,
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
	"David S. Miller" <davem@...emloft.net>,
	Andreas Larsson <andreas@...sler.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	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>,
	Andrew Donnellan <ajd@...ux.ibm.com>,
	Benjamin Gray <bgray@...ux.ibm.com>,
	Frederic Weisbecker <frederic@...nel.org>,
	Xin Li <xin3.li@...el.com>, Kees Cook <keescook@...omium.org>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Tony Battersby <tonyb@...ernetics.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Brian Gerst <brgerst@...il.com>, Leonardo Bras <leobras@...hat.com>,
	Imran Khan <imran.f.khan@...cle.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Rik van Riel <riel@...riel.com>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	David Vernet <void@...ifault.com>,
	Julia Lawall <julia.lawall@...ia.fr>, linux-alpha@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org,
	linux-openrisc@...r.kernel.org, linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-sh@...r.kernel.org,
	sparclinux@...r.kernel.org, linux-pm@...r.kernel.org,
	x86@...nel.org
Subject: Re: [PATCH v2 00/14] Introducing TIF_NOTIFY_IPI flag

On Fri, Jun 14, 2024 at 12:48:37PM +0200, Vincent Guittot wrote:

> The main problem is that need_resched becomes somewhat meaningless
> because it doesn't  only mean "I need to resched a task" and we have
> to add more tests around even for those not using polling

The converse problem is that you're adding a bunch of atomic ops that
might be avoided.

It might now need to set both the RESCHED and IPI flags -- and clear
them again.