linux-kernel - Re: Module loading/unloading and "The Stop Machine"

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Message-ID: <p73prup8awh.fsf@bingen.suse.de>
Date:	Fri, 22 Feb 2008 12:53:50 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Max Krasnyanskiy <maxk@...lcomm.com>
Cc:	Tejun Heo <htejun@...il.com>, rusty@...tcorp.com.au,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: Module loading/unloading and "The Stop Machine"

Max Krasnyanskiy <maxk@...lcomm.com> writes:
>
> static struct module *load_module(void __user *umod,
>                                  unsigned long len,
>                                  const char __user *uargs)
> {
>      ...
>
>      /* Now sew it into the lists so we can get lockdep and oops
>         * info during argument parsing.  Noone should access us, since
>         * strong_try_module_get() will fail. */
>        stop_machine_run(__link_module, mod, NR_CPUS);
>      ...
> }

Wow you found some really bad code. I bet it wouldn't be that
difficult to fix the code to allow oops safe list insertion
without using the big stop machine overkill hammer.

-Andi
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