[PATCH 6/8] Per container OOM killer

[Pavel Emelianov <xemul@sw.ru>]

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When container is completely out of memory some tasks should
die. This is unfair to kill the current task, so a task with
the largest RSS is chosen and killed. The code re-uses current
OOM killer select_bad_process() for task selection.

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diff -upr linux-2.6.20.orig/include/linux/rss_container.h linux-2.6.20-2/include/linux/rss_container.h
--- linux-2.6.20.orig/include/linux/rss_container.h	2007-04-09 11:26:12.000000000 +0400
+++ linux-2.6.20-2/include/linux/rss_container.h	2007-04-09 11:26:06.000000000 +0400
@@ -19,6 +19,7 @@
 void container_rss_add(struct page_container *);
 void container_rss_del(struct page_container *);
 void container_rss_release(struct page_container *);
+void container_out_of_memory(struct rss_container *);
 
 void mm_init_container(struct mm_struct *mm, struct task_struct *tsk);
 void mm_free_container(struct mm_struct *mm);
diff -upr linux-2.6.20.orig/mm/oom_kill.c linux-2.6.20-2/mm/oom_kill.c
--- linux-2.6.20.orig/mm/oom_kill.c	2007-03-06 19:09:50.000000000 +0300
+++ linux-2.6.20-2/mm/oom_kill.c	2007-04-09 11:26:06.000000000 +0400
@@ -24,6 +24,7 @@
 #include <linux/cpuset.h>
 #include <linux/module.h>
 #include <linux/notifier.h>
+#include <linux/rss_container.h>
 
 int sysctl_panic_on_oom;
 /* #define DEBUG */
@@ -47,7 +48,8 @@ int sysctl_panic_on_oom;
  *    of least surprise ... (be careful when you change it)
  */
 
-unsigned long badness(struct task_struct *p, unsigned long uptime)
+unsigned long badness(struct task_struct *p, unsigned long uptime,
+		struct rss_container *rss)
 {
 	unsigned long points, cpu_time, run_time, s;
 	struct mm_struct *mm;
@@ -60,6 +62,13 @@ unsigned long badness(struct task_struct
 		return 0;
 	}
 
+#ifdef CONFIG_RSS_CONTAINER
+	if (rss != NULL && mm->rss_container != rss) {
+		task_unlock(p);
+		return 0;
+	}
+#endif
+
 	/*
 	 * The memory size of the process is the basis for the badness.
 	 */
@@ -200,7 +209,8 @@ static inline int constrained_alloc(stru
  *
  * (not docbooked, we don't want this one cluttering up the manual)
  */
-static struct task_struct *select_bad_process(unsigned long *ppoints)
+static struct task_struct *select_bad_process(unsigned long *ppoints,
+		struct rss_container *rss)
 {
 	struct task_struct *g, *p;
 	struct task_struct *chosen = NULL;
@@ -254,7 +264,7 @@ static struct task_struct *select_bad_pr
 		if (p->oomkilladj == OOM_DISABLE)
 			continue;
 
-		points = badness(p, uptime.tv_sec);
+		points = badness(p, uptime.tv_sec, rss);
 		if (points > *ppoints || !chosen) {
 			chosen = p;
 			*ppoints = points;
@@ -435,7 +445,7 @@ retry:
 		 * Rambo mode: Shoot down a process and hope it solves whatever
 		 * issues we may have.
 		 */
-		p = select_bad_process(&points);
+		p = select_bad_process(&points, NULL);
 
 		if (PTR_ERR(p) == -1UL)
 			goto out;
@@ -464,3 +474,27 @@ out:
 	if (!test_thread_flag(TIF_MEMDIE))
 		schedule_timeout_uninterruptible(1);
 }
+
+#ifdef CONFIG_RSS_CONTAINER
+void container_out_of_memory(struct rss_container *rss)
+{
+	unsigned long points = 0;
+	struct task_struct *p;
+
+	container_lock();
+	read_lock(&tasklist_lock);
+retry:
+	p = select_bad_process(&points, rss);
+	if (PTR_ERR(p) == -1UL)
+		goto out;
+
+	if (!p)
+		p = current;
+
+	if (oom_kill_process(p, points, "Container out of memory"))
+		goto retry;
+out:
+	read_unlock(&tasklist_lock);
+	container_unlock();
+}
+#endif