Re: 2.5.68-mm2

Robert Love (rml@tech9.net)
23 Apr 2003 12:50:46 -0400


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

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