Commit 5650a43b authored by Andrew Morton's avatar Andrew Morton Committed by Christoph Hellwig

[PATCH] oom-killer locking fix

From: William Lee Irwin III <wli@holomorphy.com>, Robert Love

Add some spinlock protection around the oom-killer state.
parent 565b4425
...@@ -208,6 +208,11 @@ static void oom_kill(void) ...@@ -208,6 +208,11 @@ static void oom_kill(void)
*/ */
void out_of_memory(void) 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; static unsigned long first, last, count, lastkill;
unsigned long now, since; unsigned long now, since;
...@@ -217,6 +222,7 @@ void out_of_memory(void) ...@@ -217,6 +222,7 @@ void out_of_memory(void)
if (nr_swap_pages > 0) if (nr_swap_pages > 0)
return; return;
spin_lock(&oom_lock);
now = jiffies; now = jiffies;
since = now - last; since = now - last;
last = now; last = now;
...@@ -235,14 +241,14 @@ void out_of_memory(void) ...@@ -235,14 +241,14 @@ void out_of_memory(void)
*/ */
since = now - first; since = now - first;
if (since < HZ) if (since < HZ)
return; goto out_unlock;
/* /*
* If we have gotten only a few failures, * If we have gotten only a few failures,
* we're not really oom. * we're not really oom.
*/ */
if (++count < 10) if (++count < 10)
return; goto out_unlock;
/* /*
* If we just killed a process, wait a while * If we just killed a process, wait a while
...@@ -251,15 +257,27 @@ void out_of_memory(void) ...@@ -251,15 +257,27 @@ void out_of_memory(void)
*/ */
since = now - lastkill; since = now - lastkill;
if (since < HZ*5) if (since < HZ*5)
return; goto out_unlock;
/* /*
* Ok, really out of memory. Kill something. * Ok, really out of memory. Kill something.
*/ */
lastkill = now; lastkill = now;
/* oom_kill() sleeps */
spin_unlock(&oom_lock);
oom_kill(); oom_kill();
spin_lock(&oom_lock);
reset: reset:
/*
* 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; first = now;
count = 0; count = 0;
out_unlock:
spin_unlock(&oom_lock);
} }
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