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

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Date:	Fri, 22 Feb 2008 14:41:53 -0800
From:	Max Krasnyanskiy <maxk@...lcomm.com>
To:	Andi Kleen <andi@...stfloor.org>
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"

Hi Andi,

> 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.
Let me know if you have something in mind. When I get a chance I'll stare
some more at that code and try to come up with an alternative solution.

Thanx
Max
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