linux-kernel - Re: 2.6.25-rc3: 34TB vmalloc total -- overflow in /proc/meminfo?

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Date:	Thu, 6 Mar 2008 12:14:08 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Andi Kleen <ak@...e.de>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Pavel Machek <pavel@....cz>,
	kernel list <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: 2.6.25-rc3: 34TB vmalloc total -- overflow in /proc/meminfo?

* Andi Kleen <ak@...e.de> wrote:

> Just commenting on the subject. The 34TB are not an over/underflow. 
> x86-64 simply has so much address space reserved for vmalloc. It 
> doesn't mean of course that that much could be actually allocated in 
> real memory.

btw., the exact amount of available vmalloc space on 64-bit x86 is 32 TB 
(32768 GB), or 0x0000200000000000 hexa. (this is still only 0.0002% of 
the complete 64-bit address space [25% of the 128 TB 64-bit kernel 
address space] so we've got plenty of room)

but the first fundamental limit we'll hit on 64-bit is the 32-bit offset 
limit of binaries - this affects kernel modules, the kernel image, etc. 
We wont hit that anytime soon, but we'll eventually hit it. (user-space 
will be the first i guess)

	Ingo
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