Re: 2.5.68-mm2

[Robert Love <rml@tech9.net>]

On Wed, 2003-04-23 at 05:59, William Lee Irwin III wrote:

> rml and I coordinated to put together a small patch (combining both
> our own) for properly locking the static variables in out_of_memory().
> There's not any evidence things are going wrong here now, but it at
> least addresses the visible lack of locking in out_of_memory().

Thank you for posting this, wli.

> -	first = now;
> +	/*
> +	 * We dropped the lock above, so check to be sure the variable
> +	 * first only ever increases to prevent false OOM's.
> +	 */
> +	if (time_after(now, first))
> +		first = now;

Just thinking... this little bit is actually a bug even on UP sans
kernel preemption, too, since oom_kill() can sleep.  If it sleeps, and
another process enters out_of_memory(), 'now' and 'first' will be out of
sync.

So I think this patch is a Good Thing in more ways than the obvious SMP
or kernel preemption issue.

	Robert Love