linux-kernel - Re: [PATCH v14 09/12] unwind deferred: Use SRCU unwind_deferred_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] [day] [month] [year] [list]

Message-ID: <3eec6c5d-2e4c-41c0-ac43-6df51faeb670@paulmck-laptop>
Date: Thu, 17 Jul 2025 09:54:36 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Steven Rostedt <rostedt@...nel.org>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org, bpf@...r.kernel.org,
	x86@...nel.org, Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrii Nakryiko <andrii@...nel.org>,
	Indu Bhagat <indu.bhagat@...cle.com>,
	"Jose E. Marchesi" <jemarch@....org>,
	Beau Belgrave <beaub@...ux.microsoft.com>,
	Jens Remus <jremus@...ux.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jens Axboe <axboe@...nel.dk>, Florian Weimer <fweimer@...hat.com>,
	Sam James <sam@...too.org>
Subject: Re: [PATCH v14 09/12] unwind deferred: Use SRCU
 unwind_deferred_task_work()

On Thu, Jul 17, 2025 at 12:38:35PM -0400, Steven Rostedt wrote:
> On Thu, 17 Jul 2025 09:27:34 -0700
> "Paul E. McKenney" <paulmck@...nel.org> wrote:
> 
> > > Two, I'm still grasping at the concept of srcu_fast (and srcu_lite for
> > > that matter), where I rather be slow and safe than optimize and be
> > > unsafe. The code where this is used may be faulting in user space
> > > memory, so it doesn't need the micro-optimizations now.  
> > 
> > Straight-up SRCU and guard(srcu), then?  Both are already in mainline.
> > 
> > Or are those read-side smp_mb() calls a no-go for this code?
> 
> As I stated, the read-side is likely going to be faulting in user space
> memory. I don't think one or two smp_mb() will really make much of a
> difference ;-)
> 
> It's not urgent. If it can be switched to srcu_fast, we can do it later.

Very good, we will continue with our removal of SRCU-lite, and I might
as well add guard(srcu_fast) in my current series.

							Thanx, Paul