linux-kernel - Re: [PATCH 00/10] perf/uprobe: Optimize uprobes

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: <CAEf4BzZp31-skJQWcv_H+iTG52dAbX+YeXkZ4d+HMaXRyXhJQA@mail.gmail.com>
Date: Tue, 9 Jul 2024 09:42:00 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: paulmck@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>, Masami Hiramatsu <mhiramat@...nel.org>, mingo@...nel.org, 
	andrii@...nel.org, linux-kernel@...r.kernel.org, rostedt@...dmis.org, 
	oleg@...hat.com, jolsa@...nel.org, clm@...a.com, bpf <bpf@...r.kernel.org>, 
	willy@...radead.org
Subject: Re: [PATCH 00/10] perf/uprobe: Optimize uprobes

On Tue, Jul 9, 2024 at 7:11 AM Paul E. McKenney <paulmck@...nel.org> wrote:
>
> On Tue, Jul 09, 2024 at 11:01:53AM +0200, Peter Zijlstra wrote:
> > On Mon, Jul 08, 2024 at 05:25:14PM -0700, Andrii Nakryiko wrote:
> >
> > > Quick profiling for the 8-threaded benchmark shows that we spend >20%
> > > in mmap_read_lock/mmap_read_unlock in find_active_uprobe. I think
> > > that's what would prevent uprobes from scaling linearly. If you have
> > > some good ideas on how to get rid of that, I think it would be
> > > extremely beneficial.
> >
> > That's find_vma() and friends. I started RCU-ifying that a *long* time
> > ago when I started the speculative page fault patches. I sorta lost
> > track of that effort, Willy where are we with that?
> >
> > Specifically, how feasible would it be to get a simple RCU based
> > find_vma() version sorted these days?
>
> Liam's and Willy's Maple Tree work, combined with Suren's per-VMA locking
> combined with some of Vlastimil's slab work is pushing in that direction.
> I believe that things are getting pretty close.

Yep, I realized that this might be a solution right after asking the
question :) I've been recently exposed to per-VMA locking, so I might
take a look at this later.

>
> As with your work in 2010 and MIT guy's work in 2013, corner-case
> correctness and corner-case performance regressions continue to provide
> quite a bit of good clean fun.
>
>                                                         Thanx, Paul