1 files changed, 79 insertions, 18 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index b9af136e5cfa..bada3d03119f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -21,6 +21,8 @@
 #include <linux/timex.h>
 #include <linux/jiffies.h>
 #include <linux/cpuset.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
 
 int sysctl_panic_on_oom;
 /* #define DEBUG */
@@ -58,6 +60,12 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
         }
 
         /*
+         * swapoff can easily use up all memory, so kill those first.
+         */
+        if (p->flags & PF_SWAPOFF)
+                return ULONG_MAX;
+
+        /*
          * The memory size of the process is the basis for the badness.
          */
         points = mm->total_vm;
@@ -127,6 +135,14 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
                 points /= 4;
 
         /*
+         * If p's nodes don't overlap ours, it may still help to kill p
+         * because p may have allocated or otherwise mapped memory on
+         * this node before. However it will be less likely.
+         */
+        if (!cpuset_excl_nodes_overlap(p))
+                points /= 8;
+
+        /*
          * Adjust the score by oomkilladj.
          */
         if (p->oomkilladj) {
@@ -161,8 +177,7 @@ static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask)
 
         for (z = zonelist->zones; *z; z++)
                 if (cpuset_zone_allowed(*z, gfp_mask))
-                        node_clear((*z)->zone_pgdat->node_id,
-                                        nodes);
+                        node_clear(zone_to_nid(*z), nodes);
                 else
                         return CONSTRAINT_CPUSET;
 
@@ -191,25 +206,38 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
                 unsigned long points;
                 int releasing;
 
+                /* skip kernel threads */
+                if (!p->mm)
+                        continue;
                 /* 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 wait for it
                  * to finish before killing some other task by mistake.
+                 *
+                 * However, if p is the current task, we allow the 'kill' to
+                 * go ahead if it is exiting: this will simply set TIF_MEMDIE,
+                 * which will allow it to gain access to memory reserves in
+                 * the process of exiting and releasing its resources.
+                 * Otherwise we could get an OOM deadlock.
                  */
                 releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
                                                 p->flags & PF_EXITING;
-                if (releasing && !(p->flags & PF_DEAD))
+                if (releasing) {
+                        /* PF_DEAD tasks have already released their mm */
+                        if (p->flags & PF_DEAD)
+                                continue;
+                        if (p->flags & PF_EXITING && p == current) {
+                                chosen = p;
+                                *ppoints = ULONG_MAX;
+                                break;
+                        }
                         return ERR_PTR(-1UL);
-                if (p->flags & PF_SWAPOFF)
-                        return p;
+                }
+                if (p->oomkilladj == OOM_DISABLE)
+                        continue;
 
                 points = badness(p, uptime.tv_sec);
                 if (points > *ppoints || !chosen) {
@@ -221,9 +249,9 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
 }
 
 /**
- * We must be careful though to never send SIGKILL a process with
- * CAP_SYS_RAW_IO set, send SIGTERM instead (but it's unlikely that
- * we select a process with CAP_SYS_RAW_IO set).
+ * Send SIGKILL to the selected  process irrespective of  CAP_SYS_RAW_IO
+ * flag though it's unlikely that  we select a process with CAP_SYS_RAW_IO
+ * set.
  */
 static void __oom_kill_task(struct task_struct *p, const char *message)
 {
@@ -241,8 +269,11 @@ static void __oom_kill_task(struct task_struct *p, const char *message)
                 return;
         }
         task_unlock(p);
-        printk(KERN_ERR "%s: Killed process %d (%s).\n",
+
+        if (message) {
+                printk(KERN_ERR "%s: Killed process %d (%s).\n",
                                 message, p->pid, p->comm);
+        }
 
         /*
          * We give our sacrificial lamb high priority and access to
@@ -293,8 +324,17 @@ static int oom_kill_process(struct task_struct *p, unsigned long points,
         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);
+        /*
+         * If the task is already exiting, don't alarm the sysadmin or kill
+         * its children or threads, just set TIF_MEMDIE so it can die quickly
+         */
+        if (p->flags & PF_EXITING) {
+                __oom_kill_task(p, NULL);
+                return 0;
+        }
+
+        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);
@@ -306,6 +346,20 @@ static int oom_kill_process(struct task_struct *p, unsigned long points,
         return oom_kill_task(p, message);
 }
 
+static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
+
+int register_oom_notifier(struct notifier_block *nb)
+{
+        return blocking_notifier_chain_register(&oom_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(register_oom_notifier);
+
+int unregister_oom_notifier(struct notifier_block *nb)
+{
+        return blocking_notifier_chain_unregister(&oom_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_oom_notifier);
+
 /**
  * out_of_memory - kill the "best" process when we run out of memory
  *
@@ -318,10 +372,17 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
 {
         struct task_struct *p;
         unsigned long points = 0;
+        unsigned long freed = 0;
+
+        blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
+        if (freed > 0)
+                /* Got some memory back in the last second. */
+                return;
 
         if (printk_ratelimit()) {
-                printk("oom-killer: gfp_mask=0x%x, order=%d\n",
-                        gfp_mask, order);
+                printk(KERN_WARNING "%s invoked oom-killer: "
+                        "gfp_mask=0x%x, order=%d, oomkilladj=%d\n",
+                        current->comm, gfp_mask, order, current->oomkilladj);
                 dump_stack();
                 show_mem();
         }