linux-kernel - Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI context

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: <20151201234437.GA8644@n2100.arm.linux.org.uk>
Date:	Tue, 1 Dec 2015 23:44:37 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Petr Mladek <pmladek@...e.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Daniel Thompson <daniel.thompson@...aro.org>,
	Jiri Kosina <jkosina@...e.com>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-arm-kernel@...ts.infradead.org,
	adi-buildroot-devel@...ts.sourceforge.net,
	linux-cris-kernel@...s.com, linux-mips@...ux-mips.org,
	linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
	linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
	Petr Mladek <pmladek@...e.cz>
Subject: Re: [PATCH v2 3/5] printk/nmi: Try hard to print Oops message in NMI
 context

On Fri, Nov 27, 2015 at 12:09:30PM +0100, Petr Mladek wrote:
> What we can do, though, is to zap all printk locks. We already do this
> when a printk recursion is detected. This should be safe because
> the system is crashing and there shouldn't be any printk caller
> that would cause the deadlock.

What about serial consoles which may call out to subsystems like the
clk subsystem to enable a clock, which would want to take their own
spinlocks in addition to the serial console driver?

I don't see bust_spinlocks() dealing with any of these locks, so IMHO
trying to make this work in NMI context strikes me as making the
existing solution more unreliable on ARM systems.

-- 
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/