On Wed, Aug 12, 2015 at 10:52 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I get the feeling this file should be rewritten. But that's not going
> to happen. The "let's just cache the last value for one jiffy" seemed
> to be the minimal fixup to it.

Here's a totally untested patch (I'll reboot and test soon - it does
at least compile for me).

Notice the total lack of locking, which means that it's fundamentally
racy. I really can't find it inside myself to care. Introducing those
vmalloc fields was a mistake to begin with, any races here are "ok, we
get values that were valid at some point, but it might have been a
second ago".

And I also can't find it in myself to care about the "on 32-bit,
jiffies wraps in 49 days if HZ is 1000". If somebody carefully avoids
ever reading /proc/meminfo for 49 days, and then reads it in _just_
the right second, and gets a really stale value, I'm just going to do
my honey badger impression.

Because we really shouldn't have added the vmalloc information to
/proc/meminfo to begin with, and nobody ever cares about those values
anyway.

Comments?

                Linus