Re: [RFC] ps command race fix

[Andrew Morton]

On Tue, 25 Jul 2006 11:08:35 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:

> > Then the seek and read and such semantics are nice and stable and
> > simple.
> > 
> yes...
> I think snapshot at open() is okay.

We cannot do a single kmalloc() like cpuset does.

The kernel presently kind-of guarantees that a 32k kmalloc() will work,
although the VM might have to do very large amounts of work to achieve it.

But 32k is only 8192 processes, so a snapshot will need multiple
allocations and a list and trouble dropping and retaking tasklist_lock to
allocate memory and keeping things stable while doing that.  I suspect
it'll end up ugly.

And it permits userspace to pin rather a lot of memory.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/