Re: [PATCH 1/9] exec: add a global execve counter

[Linus Torvalds]

On Sun, Mar 11, 2012 at 10:25 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
>
> It should be per-process, signal_struct makes more sense. Or may be
> mm_struct.

I do wonder if we shouldn't just consider the "struct mm_struct"
pointer to *be* the unique exec ID. It's what /proc/pid/mem does, and
it works fine, and allows us to just use a normal pointer as the
unique ID.

Just increment the mm_count for the thing, and hold a reference to it,
and now you're all done.

By definition an execve() will change the mm struct, and if you have a
refcount to the old one, it won't be re-used. And it's not a huge
allocation, although it would definitely be good to put that thing on
a diet.

And as long as we use 'mm_count', not 'mm_users', it won't pin
anything else in memory. That's part of the whole point of the
doubly-refcounted thing.

                      Linus
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