From 16d200a58f939178eb955a478bc6af0c7e6bbab6 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@osdl.org>
Date: Tue, 18 Apr 2006 22:20:38 -0700
Subject: [PATCH] --- yaml --- r: 25978 b: refs/heads/master c:
 97c2c9b84d0c1edf4926b13661d5af3f0edccbce h: refs/heads/master v: v3

---
 [refs]              |  2 +-
 trunk/mm/oom_kill.c | 26 ++++++++++++++++++--------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/[refs] b/[refs]
index 9db411d5c00b..f38e18cc8881 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 75129e297e861e6c61038aa4cdbf604b022de4ff
+refs/heads/master: 97c2c9b84d0c1edf4926b13661d5af3f0edccbce
diff --git a/trunk/mm/oom_kill.c b/trunk/mm/oom_kill.c
index 78747afad6b0..9a643c4bf77c 100644
--- a/trunk/mm/oom_kill.c
+++ b/trunk/mm/oom_kill.c
@@ -46,15 +46,25 @@
 unsigned long badness(struct task_struct *p, unsigned long uptime)
 {
 	unsigned long points, cpu_time, run_time, s;
-	struct list_head *tsk;
+	struct mm_struct *mm;
+	struct task_struct *child;
 
-	if (!p->mm)
+	task_lock(p);
+	mm = p->mm;
+	if (!mm) {
+		task_unlock(p);
 		return 0;
+	}
 
 	/*
 	 * The memory size of the process is the basis for the badness.
 	 */
-	points = p->mm->total_vm;
+	points = mm->total_vm;
+
+	/*
+	 * After this unlock we can no longer dereference local variable `mm'
+	 */
+	task_unlock(p);
 
 	/*
 	 * Processes which fork a lot of child processes are likely
@@ -64,11 +74,11 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
 	 * child is eating the vast majority of memory, adding only half
 	 * to the parents will make the child our kill candidate of choice.
 	 */
-	list_for_each(tsk, &p->children) {
-		struct task_struct *chld;
-		chld = list_entry(tsk, struct task_struct, sibling);
-		if (chld->mm != p->mm && chld->mm)
-			points += chld->mm->total_vm/2 + 1;
+	list_for_each_entry(child, &p->children, sibling) {
+		task_lock(child);
+		if (child->mm != mm && child->mm)
+			points += child->mm->total_vm/2 + 1;
+		task_unlock(child);
 	}
 
 	/*