From: William Lee Irwin III <wli@holomorphy.com>
To: Andrew Morton <akpm@digeo.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, rml@tech9.net
Subject: Re: 2.5.68-mm2
Date: Wed, 23 Apr 2003 02:59:26 -0700 [thread overview]
Message-ID: <20030423095926.GJ8931@holomorphy.com> (raw)
In-Reply-To: <20030423012046.0535e4fd.akpm@digeo.com>
On Wed, Apr 23, 2003 at 01:20:46AM -0700, Andrew Morton wrote:
> http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.68/2.5.68-mm2.gz
> Will appear sometime at:
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.5/2.5.68/2.5.68-mm2/
> . Zillions of new fixes.
> . I got tired of the objrmap code going BUG under stress, so it is now in
> disgrace in the experimental/ directory.
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().
Applies cleanly to 2.5.68-mm2.
-- wli
diff -urpN mm1-2.5.68-1/mm/oom_kill.c mm1-2.5.68-1A/mm/oom_kill.c
--- mm1-2.5.68-1/mm/oom_kill.c 2003-04-20 00:24:46.000000000 -0700
+++ mm1-2.5.68-1A/mm/oom_kill.c 2003-04-22 21:43:40.000000000 -0700
@@ -208,6 +208,11 @@ static void oom_kill(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;
unsigned long now, since;
@@ -217,6 +222,7 @@ void out_of_memory(void)
if (nr_swap_pages > 0)
return;
+ spin_lock(&oom_lock);
now = jiffies;
since = now - last;
last = now;
@@ -235,14 +241,14 @@ void out_of_memory(void)
*/
since = now - first;
if (since < HZ)
- return;
+ goto out_unlock;
/*
* If we have gotten only a few failures,
* we're not really oom.
*/
if (++count < 10)
- return;
+ goto out_unlock;
/*
* If we just killed a process, wait a while
@@ -251,15 +257,27 @@ void out_of_memory(void)
*/
since = now - lastkill;
if (since < HZ*5)
- return;
+ 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);
reset:
- 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;
count = 0;
+
+out_unlock:
+ spin_unlock(&oom_lock);
}
next prev parent reply other threads:[~2003-04-23 9:47 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-23 8:20 2.5.68-mm2 Andrew Morton
2003-04-23 9:59 ` William Lee Irwin III [this message]
2003-04-23 16:50 ` 2.5.68-mm2 Robert Love
2003-04-23 16:57 ` 2.5.68-mm2 Martin J. Bligh
2003-04-23 17:11 ` 2.5.68-mm2 Robert Love
2003-04-24 9:14 ` 2.5.68-mm2 William Lee Irwin III
2003-04-23 14:51 ` 2.5.68-mm2 Martin J. Bligh
2003-04-23 15:14 ` 2.5.68-mm2 Alex Tomas
2003-04-23 21:46 ` 2.5.68-mm2 Andrew Morton
2003-04-23 21:47 ` 2.5.68-mm2 Martin J. Bligh
2003-04-24 3:39 ` 2.5.68-mm2 Benjamin LaHaise
2003-04-24 21:13 ` 2.5.68-mm2 Martin J. Bligh
2003-04-24 23:13 ` objrmap (was 2.5.68-mm2) Martin J. Bligh
2003-04-24 3:36 ` 2.5.68-mm2 Benjamin LaHaise
2003-04-24 20:24 ` 2.5.68-mm2 Bill Davidsen
2003-04-24 20:33 ` 2.5.68-mm2 Benjamin LaHaise
2003-04-25 17:56 ` 2.5.68-mm2 Bill Davidsen
2003-04-25 18:20 ` 2.5.68-mm2 Randy.Dunlap
2003-04-25 18:27 ` 2.5.68-mm2 Robert Love
2003-04-25 18:49 ` 2.5.68-mm2 Martin J. Bligh
2003-04-26 10:34 ` 2.5.68-mm2 Bill Davidsen
2003-04-26 15:34 ` 2.5.68-mm2 Martin J. Bligh
2003-05-01 6:19 ` [BUG] 2.5.68-mm2 and list.h Alexander Hoogerhuis
2003-05-01 6:31 ` Andrew Morton
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