X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=kernel%2Fpower%2Fprocess.c;h=6ff55e749197d3aaca24c806caab42d683085ce3;hb=24a92c14505e9768d206ba8133054298d64103e6;hp=1b212bee1510cb22b6e1df1c2ba00fff6b6cf4e6;hpb=5b70260e8f6bf80def50b2126e2ded2cb8e32012;p=firefly-linux-kernel-4.4.55.git

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 1b212bee1510..6ff55e749197 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -30,9 +30,10 @@ static int try_to_freeze_tasks(bool user_only)
 	unsigned int todo;
 	bool wq_busy = false;
 	struct timeval start, end;
-	u64 elapsed_csecs64;
-	unsigned int elapsed_csecs;
+	u64 elapsed_msecs64;
+	unsigned int elapsed_msecs;
 	bool wakeup = false;
+	int sleep_usecs = USEC_PER_MSEC;
 
 	do_gettimeofday(&start);
 
@@ -68,22 +69,25 @@ static int try_to_freeze_tasks(bool user_only)
 
 		/*
 		 * We need to retry, but first give the freezing tasks some
-		 * time to enter the refrigerator.
+		 * time to enter the refrigerator.  Start with an initial
+		 * 1 ms sleep followed by exponential backoff until 8 ms.
 		 */
-		msleep(10);
+		usleep_range(sleep_usecs / 2, sleep_usecs);
+		if (sleep_usecs < 8 * USEC_PER_MSEC)
+			sleep_usecs *= 2;
 	}
 
 	do_gettimeofday(&end);
-	elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
-	do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
-	elapsed_csecs = elapsed_csecs64;
+	elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
+	do_div(elapsed_msecs64, NSEC_PER_MSEC);
+	elapsed_msecs = elapsed_msecs64;
 
 	if (todo) {
 		printk("\n");
-		printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
+		printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds "
 		       "(%d tasks refusing to freeze, wq_busy=%d):\n",
 		       wakeup ? "aborted" : "failed",
-		       elapsed_csecs / 100, elapsed_csecs % 100,
+		       elapsed_msecs / 1000, elapsed_msecs % 1000,
 		       todo - wq_busy, wq_busy);
 
 		if (!wakeup) {
@@ -96,13 +100,35 @@ static int try_to_freeze_tasks(bool user_only)
 			read_unlock(&tasklist_lock);
 		}
 	} else {
-		printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
-			elapsed_csecs % 100);
+		printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
+			elapsed_msecs % 1000);
 	}
 
 	return todo ? -EBUSY : 0;
 }
 
+/*
+ * Returns true if all freezable tasks (except for current) are frozen already
+ */
+static bool check_frozen_processes(void)
+{
+	struct task_struct *g, *p;
+	bool ret = true;
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, p) {
+		if (p != current && !freezer_should_skip(p) &&
+		    !frozen(p)) {
+			ret = false;
+			goto done;
+		}
+	}
+done:
+	read_unlock(&tasklist_lock);
+
+	return ret;
+}
+
 /**
  * freeze_processes - Signal user space processes to enter the refrigerator.
  *
@@ -111,6 +137,7 @@ static int try_to_freeze_tasks(bool user_only)
 int freeze_processes(void)
 {
 	int error;
+	int oom_kills_saved;
 
 	error = __usermodehelper_disable(UMH_FREEZING);
 	if (error)
@@ -121,12 +148,27 @@ int freeze_processes(void)
 
 	printk("Freezing user space processes ... ");
 	pm_freezing = true;
+	oom_kills_saved = oom_kills_count();
 	error = try_to_freeze_tasks(true);
 	if (!error) {
-		printk("done.");
 		__usermodehelper_set_disable_depth(UMH_DISABLED);
 		oom_killer_disable();
+
+		/*
+		 * There might have been an OOM kill while we were
+		 * freezing tasks and the killed task might be still
+		 * on the way out so we have to double check for race.
+		 */
+		if (oom_kills_count() != oom_kills_saved &&
+				!check_frozen_processes()) {
+			__usermodehelper_set_disable_depth(UMH_ENABLED);
+			printk("OOM in progress.");
+			error = -EBUSY;
+			goto done;
+		}
+		printk("done.");
 	}
+done:
 	printk("\n");
 	BUG_ON(in_atomic());