X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=mm%2Foom_kill.c;h=223d9ccb7d64b6b28f5642ba3ab12629a170419a;hb=acc9252a36dcefbcdae12f88566300a80d925e11;hp=bada3d03119ff01381d6d47c1b828b59c3867106;hpb=fecf3404f4aba6d0edeba31eeb018cbb6326dff2;p=karo-tx-linux.git

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index bada3d03119f..223d9ccb7d64 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -15,6 +15,7 @@
  *  kernel subsystems and hints as to where to find out what things do.
  */
 
+#include <linux/oom.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/swap.h>
@@ -204,15 +205,29 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
 	do_posix_clock_monotonic_gettime(&uptime);
 	do_each_thread(g, p) {
 		unsigned long points;
-		int releasing;
 
-		/* skip kernel threads */
+		/*
+		 * skip kernel threads and tasks which have already released
+		 * their mm.
+		 */
 		if (!p->mm)
 			continue;
-		/* skip the init task with pid == 1 */
-		if (p->pid == 1)
+		/* skip the init task */
+		if (is_init(p))
 			continue;
 
+		/*
+		 * This task already has access to memory reserves and is
+		 * being killed. Don't allow any other task access to the
+		 * memory reserve.
+		 *
+		 * Note: this may have a chance of deadlock if it gets
+		 * blocked waiting for another task which itself is waiting
+		 * for memory. Is there a better alternative?
+		 */
+		if (test_tsk_thread_flag(p, TIF_MEMDIE))
+			return ERR_PTR(-1UL);
+
 		/*
 		 * This is in the process of releasing memory so wait for it
 		 * to finish before killing some other task by mistake.
@@ -221,21 +236,16 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
 		 * 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.
+		 * Otherwise we could get an easy OOM deadlock.
 		 */
-		releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
-						p->flags & PF_EXITING;
-		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_EXITING) {
+			if (p != current)
+				return ERR_PTR(-1UL);
+
+			chosen = p;
+			*ppoints = ULONG_MAX;
 		}
+
 		if (p->oomkilladj == OOM_DISABLE)
 			continue;
 
@@ -245,6 +255,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
 			*ppoints = points;
 		}
 	} while_each_thread(g, p);
+
 	return chosen;
 }
 
@@ -253,27 +264,22 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
  * 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)
+static void __oom_kill_task(struct task_struct *p, int verbose)
 {
-	if (p->pid == 1) {
+	if (is_init(p)) {
 		WARN_ON(1);
 		printk(KERN_WARNING "tried to kill init!\n");
 		return;
 	}
 
-	task_lock(p);
-	if (!p->mm || p->mm == &init_mm) {
+	if (!p->mm) {
 		WARN_ON(1);
 		printk(KERN_WARNING "tried to kill an mm-less task!\n");
-		task_unlock(p);
 		return;
 	}
-	task_unlock(p);
 
-	if (message) {
-		printk(KERN_ERR "%s: Killed process %d (%s).\n",
-				message, p->pid, p->comm);
-	}
+	if (verbose)
+		printk(KERN_ERR "Killed process %d (%s)\n", p->pid, p->comm);
 
 	/*
 	 * We give our sacrificial lamb high priority and access to
@@ -286,7 +292,7 @@ static void __oom_kill_task(struct task_struct *p, const char *message)
 	force_sig(SIGKILL, p);
 }
 
-static int oom_kill_task(struct task_struct *p, const char *message)
+static int oom_kill_task(struct task_struct *p)
 {
 	struct mm_struct *mm;
 	struct task_struct *g, *q;
@@ -302,18 +308,28 @@ static int oom_kill_task(struct task_struct *p, const char *message)
 	 * However, this is of no concern to us.
 	 */
 
-	if (mm == NULL || mm == &init_mm)
+	if (mm == NULL)
 		return 1;
 
-	__oom_kill_task(p, message);
+	/*
+	 * Don't kill the process if any threads are set to OOM_DISABLE
+	 */
+	do_each_thread(g, q) {
+		if (q->mm == mm && p->oomkilladj == OOM_DISABLE)
+			return 1;
+	} while_each_thread(g, q);
+
+	__oom_kill_task(p, 1);
+
 	/*
 	 * kill all processes that share the ->mm (i.e. all threads),
-	 * but are in a different thread group
+	 * but are in a different thread group. Don't let them have access
+	 * to memory reserves though, otherwise we might deplete all memory.
 	 */
-	do_each_thread(g, q)
+	do_each_thread(g, q) {
 		if (q->mm == mm && q->tgid != p->tgid)
-			__oom_kill_task(q, message);
-	while_each_thread(g, q);
+			force_sig(SIGKILL, p);
+	} while_each_thread(g, q);
 
 	return 0;
 }
@@ -329,21 +345,22 @@ static int oom_kill_process(struct task_struct *p, unsigned long points,
 	 * its children or threads, just set TIF_MEMDIE so it can die quickly
 	 */
 	if (p->flags & PF_EXITING) {
-		__oom_kill_task(p, NULL);
+		__oom_kill_task(p, 0);
 		return 0;
 	}
 
-	printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li"
-			" and children.\n", p->pid, p->comm, points);
+	printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
+					message, 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))
+		if (!oom_kill_task(c))
 			return 0;
 	}
-	return oom_kill_task(p, message);
+	return oom_kill_task(p);
 }
 
 static BLOCKING_NOTIFIER_HEAD(oom_notify_list);