X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=mm%2Foom_kill.c;h=f9c115a6291d7dc6cc2e7cadd5a627515992e8ff;hb=43bc926fffd92024b46cafaf7350d669ba9ca884;hp=ed0cee4e6c80a09efd3fc9f5d0e7bb05287fa992;hpb=5273a3df6485dc2ad6aa7ddd441b9a21970f003b;p=linux-2.6.git

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index ed0cee4e6..f9c115a62 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -6,8 +6,8 @@
  *	for goading me into coding this file...
  *
  *  The routines in this file are used to kill a process when
- *  we're seriously out of memory. This gets called from kswapd()
- *  in linux/mm/vmscan.c when we really run out of memory.
+ *  we're seriously out of memory. This gets called from __alloc_pages()
+ *  in mm/page_alloc.c when we really run out of memory.
  *
  *  Since we won't call these routines often (on a well-configured
  *  machine) this file will double as a 'coding guide' and a signpost
@@ -20,12 +20,14 @@
 #include <linux/swap.h>
 #include <linux/timex.h>
 #include <linux/jiffies.h>
+#include <linux/cpuset.h>
 
 /* #define DEBUG */
 
 /**
  * oom_badness - calculate a numeric value for how bad this task has been
  * @p: task struct of which task we should calculate
+ * @uptime: current uptime in seconds
  *
  * The formula used is relatively simple and documented inline in the
  * function. The main rationale is that we want to select a good task
@@ -41,27 +43,58 @@
  *    of least surprise ... (be careful when you change it)
  */
 
-static int badness(struct task_struct *p)
+unsigned long badness(struct task_struct *p, unsigned long uptime)
 {
-	int points, cpu_time, run_time, s;
+	unsigned long points, cpu_time, run_time, s;
+	struct mm_struct *mm;
+	struct task_struct *child;
 
-	if (!p->mm)
+	task_lock(p);
+	mm = p->mm;
+	if (!mm) {
+		task_unlock(p);
 		return 0;
+	}
 
-	if (p->flags & PF_MEMDIE)
-		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);
+
+	/* FIXME: add vserver badness ;) */
+
+	/*
+	 * Processes which fork a lot of child processes are likely
+	 * a good choice. We add half the vmsize of the children if they
+	 * have an own mm. This prevents forking servers to flood the
+	 * machine with an endless amount of children. In case a single
+	 * 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_entry(child, &p->children, sibling) {
+		task_lock(child);
+		if (child->mm != mm && child->mm)
+			points += child->mm->total_vm/2 + 1;
+		task_unlock(child);
+	}
 
 	/*
-	 * CPU time is in seconds and run time is in minutes. There is no
-	 * particular reason for this other than that it turned out to work
-	 * very well in practice.
+	 * CPU time is in tens of seconds and run time is in thousands
+         * of seconds. There is no particular reason for this other than
+         * that it turned out to work very well in practice.
 	 */
-	cpu_time = (p->utime + p->stime) >> (SHIFT_HZ + 3);
-	run_time = (get_jiffies_64() - p->start_time) >> (SHIFT_HZ + 10);
+	cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
+		>> (SHIFT_HZ + 3);
+
+	if (uptime >= p->start_time.tv_sec)
+		run_time = (uptime - p->start_time.tv_sec) >> 10;
+	else
+		run_time = 0;
 
 	s = int_sqrt(cpu_time);
 	if (s)
@@ -93,6 +126,17 @@ static int badness(struct task_struct *p)
 	 */
 	if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO))
 		points /= 4;
+
+	/*
+	 * Adjust the score by oomkilladj.
+	 */
+	if (p->oomkilladj) {
+		if (p->oomkilladj > 0)
+			points <<= p->oomkilladj;
+		else
+			points >>= -(p->oomkilladj);
+	}
+
 #ifdef DEBUG
 	printk(KERN_DEBUG "OOMkill: task %d (%s) got %d points\n",
 	p->pid, p->comm, points);
@@ -100,29 +144,80 @@ static int badness(struct task_struct *p)
 	return points;
 }
 
+/*
+ * Types of limitations to the nodes from which allocations may occur
+ */
+#define CONSTRAINT_NONE 1
+#define CONSTRAINT_MEMORY_POLICY 2
+#define CONSTRAINT_CPUSET 3
+
+/*
+ * Determine the type of allocation constraint.
+ */
+static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask)
+{
+#ifdef CONFIG_NUMA
+	struct zone **z;
+	nodemask_t nodes = node_online_map;
+
+	for (z = zonelist->zones; *z; z++)
+		if (cpuset_zone_allowed(*z, gfp_mask))
+			node_clear((*z)->zone_pgdat->node_id,
+					nodes);
+		else
+			return CONSTRAINT_CPUSET;
+
+	if (!nodes_empty(nodes))
+		return CONSTRAINT_MEMORY_POLICY;
+#endif
+
+	return CONSTRAINT_NONE;
+}
+
 /*
  * Simple selection loop. We chose the process with the highest
  * number of 'points'. We expect the caller will lock the tasklist.
  *
  * (not docbooked, we don't want this one cluttering up the manual)
  */
-static struct task_struct * select_bad_process(void)
+static struct task_struct *select_bad_process(unsigned long *ppoints)
 {
-	int maxpoints = 0;
 	struct task_struct *g, *p;
 	struct task_struct *chosen = NULL;
-
-	do_each_thread(g, p)
-		if (p->pid) {
-			int points = badness(p);
-			if (points > maxpoints) {
-				chosen = p;
-				maxpoints = points;
-			}
-			if (p->flags & PF_SWAPOFF)
-				return p;
+	struct timespec uptime;
+	*ppoints = 0;
+
+	do_posix_clock_monotonic_gettime(&uptime);
+	do_each_thread(g, p) {
+		unsigned long points;
+		int releasing;
+
+		/* skip the init task with pid == 1 */
+		if (p->pid == 1)
+			continue;
+		if (p->oomkilladj == OOM_DISABLE)
+			continue;
+		/* If p's nodes don't overlap ours, it won't help to kill p. */
+		if (!cpuset_excl_nodes_overlap(p))
+			continue;
+
+		/*
+		 * This is in the process of releasing memory so for wait it
+		 * to finish before killing some other task by mistake.
+		 */
+		releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
+						p->flags & PF_EXITING;
+		if (releasing && !(p->flags & PF_DEAD))
+			return ERR_PTR(-1UL);
+		if (p->flags & PF_SWAPOFF)
+			return p;
+
+		points = badness(p, uptime.tv_sec);
+		if (points > *ppoints || !chosen) {
+			chosen = p;
+			*ppoints = points;
 		}
-	while_each_thread(g, p);
+	} while_each_thread(g, p);
 	return chosen;
 }
 
@@ -131,8 +226,14 @@ static struct task_struct * select_bad_process(void)
  * CAP_SYS_RAW_IO set, send SIGTERM instead (but it's unlikely that
  * we select a process with CAP_SYS_RAW_IO set).
  */
-static void __oom_kill_task(task_t *p)
+static void __oom_kill_task(task_t *p, const char *message)
 {
+	if (p->pid == 1) {
+		WARN_ON(1);
+		printk(KERN_WARNING "tried to kill init!\n");
+		return;
+	}
+
 	task_lock(p);
 	if (!p->mm || p->mm == &init_mm) {
 		WARN_ON(1);
@@ -141,7 +242,8 @@ static void __oom_kill_task(task_t *p)
 		return;
 	}
 	task_unlock(p);
-	printk(KERN_ERR "Out of Memory: Killed process %d (%s).\n", p->pid, p->comm);
+	printk(KERN_ERR "%s: Killed process %d (%s).\n",
+				message, p->pid, p->comm);
 
 	/*
 	 * We give our sacrificial lamb high priority and access to
@@ -149,149 +251,132 @@ static void __oom_kill_task(task_t *p)
 	 * exit() and clear out its resources quickly...
 	 */
 	p->time_slice = HZ;
-	p->flags |= PF_MEMALLOC | PF_MEMDIE;
+	set_tsk_thread_flag(p, TIF_MEMDIE);
 
-	/* This process has hardware access, be more careful. */
-	if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO)) {
-		force_sig(SIGTERM, p);
-	} else {
-		force_sig(SIGKILL, p);
-	}
+	force_sig(SIGKILL, p);
 }
 
-static struct mm_struct *oom_kill_task(task_t *p)
+static int oom_kill_task(task_t *p, const char *message)
 {
-	struct mm_struct *mm = get_task_mm(p);
-	if (!mm || mm == &init_mm)
-		return NULL;
-	__oom_kill_task(p);
-	return mm;
-}
+	struct mm_struct *mm;
+	task_t * g, * q;
 
+	mm = p->mm;
 
-/**
- * oom_kill - kill the "best" process when we run out of memory
- *
- * If we run out of memory, we have the choice between either
- * killing a random task (bad), letting the system crash (worse)
- * OR try to be smart about which process to kill. Note that we
- * don't have to be perfect here, we just have to be good.
- */
-static void oom_kill(void)
-{
-	struct mm_struct *mm;
-	struct task_struct *g, *p, *q;
-	
-	read_lock(&tasklist_lock);
-retry:
-	p = select_bad_process();
+	/* WARNING: mm may not be dereferenced since we did not obtain its
+	 * value from get_task_mm(p).  This is OK since all we need to do is
+	 * compare mm to q->mm below.
+	 *
+	 * Furthermore, even if mm contains a non-NULL value, p->mm may
+	 * change to NULL at any time since we do not hold task_lock(p).
+	 * However, this is of no concern to us.
+	 */
 
-	/* Found nothing?!?! Either we hang forever, or we panic. */
-	if (!p) {
-		show_free_areas();
-		panic("Out of memory and no killable processes...\n");
-	}
+	if (mm == NULL || mm == &init_mm)
+		return 1;
 
-	mm = oom_kill_task(p);
-	if (!mm)
-		goto retry;
+	__oom_kill_task(p, message);
 	/*
 	 * kill all processes that share the ->mm (i.e. all threads),
 	 * but are in a different thread group
 	 */
 	do_each_thread(g, q)
 		if (q->mm == mm && q->tgid != p->tgid)
-			__oom_kill_task(q);
+			__oom_kill_task(q, message);
 	while_each_thread(g, q);
-	if (!p->mm)
-		printk(KERN_INFO "Fixed up OOM kill of mm-less task\n");
-	read_unlock(&tasklist_lock);
-	mmput(mm);
 
-	/*
-	 * 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;
+	return 0;
+}
+
+static int oom_kill_process(struct task_struct *p, unsigned long points,
+		const char *message)
+{
+	struct task_struct *c;
+	struct list_head *tsk;
+
+	printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li and "
+		"children.\n", p->pid, p->comm, points);
+	/* Try to kill a child first */
+	list_for_each(tsk, &p->children) {
+		c = list_entry(tsk, struct task_struct, sibling);
+		if (c->mm == p->mm)
+			continue;
+		if (!oom_kill_task(c, message))
+			return 0;
+	}
+	return oom_kill_task(p, message);
 }
 
 /**
- * out_of_memory - is the system out of memory?
+ * oom_kill - kill the "best" process when we run out of memory
+ *
+ * If we run out of memory, we have the choice between either
+ * killing a random task (bad), letting the system crash (worse)
+ * OR try to be smart about which process to kill. Note that we
+ * don't have to be perfect here, we just have to be good.
  */
-void out_of_memory(void)
+void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
 {
-	/*
-	 * 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;
+	task_t *p;
+	unsigned long points = 0;
+
+	if (printk_ratelimit()) {
+		printk("oom-killer: gfp_mask=0x%x, order=%d\n",
+			gfp_mask, order);
+		dump_stack();
+		show_mem();
+	}
 
-	/*
-	 * If we haven't tried for at least one second,
-	 * we're not really oom.
-	 */
-	since = now - first;
-	if (since < HZ)
-		goto out_unlock;
+	cpuset_lock();
+	read_lock(&tasklist_lock);
 
 	/*
-	 * If we have gotten only a few failures,
-	 * we're not really oom. 
+	 * Check if there were limitations on the allocation (only relevant for
+	 * NUMA) that may require different handling.
 	 */
-	if (++count < 10)
-		goto out_unlock;
+	switch (constrained_alloc(zonelist, gfp_mask)) {
+	case CONSTRAINT_MEMORY_POLICY:
+		oom_kill_process(current, points,
+				"No available memory (MPOL_BIND)");
+		break;
+
+	case CONSTRAINT_CPUSET:
+		oom_kill_process(current, points,
+				"No available memory in cpuset");
+		break;
+
+	case CONSTRAINT_NONE:
+retry:
+		/*
+		 * Rambo mode: Shoot down a process and hope it solves whatever
+		 * issues we may have.
+		 */
+		p = select_bad_process(&points);
+
+		if (PTR_ERR(p) == -1UL)
+			goto out;
+
+		/* Found nothing?!?! Either we hang forever, or we panic. */
+		if (!p) {
+			read_unlock(&tasklist_lock);
+			cpuset_unlock();
+			panic("Out of memory and no killable processes...\n");
+		}
 
-	/*
-	 * 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;
+		if (oom_kill_process(p, points, "Out of memory"))
+			goto retry;
 
-	/*
-	 * Ok, really out of memory. Kill something.
-	 */
-	lastkill = now;
+		break;
+	}
 
-	/* oom_kill() sleeps */
-	spin_unlock(&oom_lock);
-	oom_kill();
-	spin_lock(&oom_lock);
+out:
+	read_unlock(&tasklist_lock);
+	cpuset_unlock();
 
-reset:
 	/*
-	 * We dropped the lock above, so check to be sure the variable
-	 * first only ever increases to prevent false OOM's.
+	 * Give "p" a good chance of killing itself before we
+	 * retry to allocate memory unless "p" is current
 	 */
-	if (time_after(now, first))
-		first = now;
-	count = 0;
-
-out_unlock:
-	spin_unlock(&oom_lock);
+	if (!test_thread_flag(TIF_MEMDIE))
+		schedule_timeout_uninterruptible(1);
 }