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

From: Ingo Molnar
Date: Thu Mar 06 2008 - 06:14:36 EST



* Andi Kleen <ak@xxxxxxx> 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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