linux-kernel - Re: [regression] Latest git has WARN

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Message-ID: <alpine.LFD.2.00.0810030901170.3185@nehalem.linux-foundation.org>
Date:	Fri, 3 Oct 2008 09:05:27 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Christian Borntraeger <borntraeger@...ibm.com>
cc:	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [regression] Latest git has WARN_ON storm with e1000e driver



On Fri, 3 Oct 2008, Christian Borntraeger wrote:
> 
> kernel_init does lock_kernel (which does preempt_disable).
> The kernel_unlock is done in init_post. As far as I can see, this happens 
> after the driver init calls.

Yes. I just came to the same conclusion: preempt_count is 1 already in 
do_one_initcall().

So this whole bug is actually because that debug test is just _broken_. It 
shouldn't be WARN_ON(preempt_count()), it should be 'might_sleep()', which 
does it right.

The right thing to check is "in_atomic() || irqs_disabled()".

Duh. That was wasted effort for a buggy test.

		Linus
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