linux-kernel - lockdep: access percpu variable too early

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-next>] [day] [month] [year] [list]

Message-ID: <CACVXFVNzN721wGm96SroK6cm4E08gs+tJtELsHvxVTCXZtX95g@mail.gmail.com>
Date:	Thu, 28 Feb 2013 23:48:00 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: lockdep: access percpu variable too early

Hi,

The percpu variables of 'lockdep_stats' and 'cpu_lock_stat'
may be accessed before percpu area is brought up in case of
CONFIG_DEBUG_LOCKDEP/CONFIG_LOCK_STAT, so these variables
in non-boot CPUs will be initialized incorrectly.

As far as I think of, there are several solutions for the
problem:

	1, just enable 'debug_locks' until percpu area is built
	2, define the two percpu variables in a simple/stupid
	percpu way inside lockdep
	3, clear these two percpu variables of non-boot CPUs
	just after percpu area is built.
	4, ignore the problem

Looks each approache have its own disadvantage, so what
is your opinion on the problem? or better approach?

Thanks,
--
Ming Lei
--
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/