linux-kernel - Re: [PATCH RFC] rcu/kfree: Do not request RCU when not needed

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: <20221103175207.GC5600@paulmck-ThinkPad-P17-Gen-1>
Date:   Thu, 3 Nov 2022 10:52:07 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Uladzislau Rezki <urezki@...il.com>
Cc:     Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] rcu/kfree: Do not request RCU when not needed

On Thu, Nov 03, 2022 at 01:44:51PM +0100, Uladzislau Rezki wrote:
> > 
> > > Though I am thinking, workqueue context is normally used to invoke
> > > code that can block, and would the issue you mentioned affect those as
> > > well, or affect RCU when those non-RCU work items block. So for
> > > example, when other things in the system that can queue things on the
> > > system_wq and block.  (I might be throwing darts in the dark).
> > > 
> > > To be safe, we can implement your suggestion which is basically a form
> > > of my initial patch.
> > > 
> > > Should we add Tejun to the thread?
> > 
> > Let's get organized first, but that would be a good thing.  Or I could
> > reach out to Tejun internally.
> > 
> > For but one thing to get organized about, maybe kfree_rcu() should be
> > using a workqueue with the WQ_MEM_RECLAIM flag set.
> > 
> It can be as an option to consider. Because such workqueue has some
> special priority for better handling of memory releasing. I can have
> a look at it closer to see how kvfree_rcu() works if it goes with WQ_MEM_RECLAIM.

Sounds good, thank you!

							Thanx, Paul