- /*
- * Make kswapd go out of the way, so "p" has a good chance of
- * killing itself before someone else gets the chance to ask
- * for more memory.
- */
- yield();
- return;
-}
-
-/**
- * out_of_memory - is the system out of memory?
- */
-void out_of_memory(void)
-{
- /*
- * oom_lock protects out_of_memory()'s static variables.
- * It's a global lock; this is not performance-critical.
- */
- static spinlock_t oom_lock = SPIN_LOCK_UNLOCKED;
- static unsigned long first, last, count, lastkill;
- unsigned long now, since;
-
- /*
- * Enough swap space left? Not OOM.
- */
- if (nr_swap_pages > 0)
- return;
-
- spin_lock(&oom_lock);
- now = jiffies;
- since = now - last;
- last = now;
-
- /*
- * If it's been a long time since last failure,
- * we're not oom.
- */
- last = now;
- if (since > 5*HZ)
- goto reset;
-
- /*
- * If we haven't tried for at least one second,
- * we're not really oom.
- */
- since = now - first;
- if (since < HZ)
- goto out_unlock;
-
- /*
- * If we have gotten only a few failures,
- * we're not really oom.
- */
- if (++count < 10)
- goto out_unlock;
-
- /*
- * If we just killed a process, wait a while
- * to give that task a chance to exit. This
- * avoids killing multiple processes needlessly.
- */
- since = now - lastkill;
- if (since < HZ*5)
- goto out_unlock;
-
- /*
- * Ok, really out of memory. Kill something.
- */
- lastkill = now;
-
- /* oom_kill() sleeps */
- spin_unlock(&oom_lock);
- oom_kill();
- spin_lock(&oom_lock);