netdev - Re: Softirq priority inversion from "softirq: reduce latencies"

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: <1456763063.648.78.camel@edumazet-ThinkPad-T530>
Date:	Mon, 29 Feb 2016 08:24:23 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Mike Galbraith <umgwanakikbuti@...il.com>,
	Francois Romieu <romieu@...zoreil.com>,
	Eric Dumazet <edumazet@...gle.com>,
	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
	dmaengine@...r.kernel.org, John Ogness <john.ogness@...utronix.de>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Softirq priority inversion from "softirq: reduce latencies"

On lun., 2016-02-29 at 07:58 -0800, Peter Hurley wrote:

> All that's happened is the first loop of NET_RX softirq has woken a
> process; that is sufficient to abort softirq and defer it for ksoftirqd.
> 
> That's why I'm saying this is a priority inversion, and one that
> will happen a lot.

Sure. This will happen every time ksoftirqd is launched.

Get rid of ksoftirqd or renice it so that you can easily be killed by
softirq storm.