linux-kernel - __virt_addr_valid vs virtual percpu areas

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Date:	Wed, 04 Mar 2009 14:57:33 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Tejun Heo <htejun@...il.com>, Ingo Molnar <mingo@...e.hu>
CC:	the arch/x86 maintainers <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	Jiri Slaby <jirislaby@...il.com>
Subject: __virt_addr_valid vs virtual percpu areas

On i386, __virt_addr_valid() has the test:

	if (system_state != SYSTEM_BOOTING && is_vmalloc_addr((void *) x))
		return false;

Why is the vmalloc area a valid virtual address while the system is 
booting?  This is biting me because I need to translate percpu addresses 
to pfns, but I only bother doing the full pagetable walk if 
virt_addr_valid() is false (otherwise I just use __pa()).

Removing this test doesn't seem to harm anything at first glance.  Is 
this OK to do in general (and can we quietly set fire to system_state 
while we're about it)?

Thanks,
    J

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