ksm-provide-support-to-use-deferrable-timers-for-scanner-thread-fix

clean up docs, fix deferrable_timer_store() error handling

Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 11 insertions, 10 deletions

diff --git a/Documentation/vm/ksm.txt b/Documentation/vm/ksm.txt
index 0481235589cc..9735c87ca363 100644
--- a/Documentation/vm/ksm.txt
+++ b/Documentation/vm/ksm.txt
@@ -88,12 +88,12 @@ pages_unshared   - how many pages unique but repeatedly checked for merging
 pages_volatile   - how many pages changing too fast to be placed in a tree
 full_scans       - how many times all mergeable areas have been scanned
 deferrable_timer - whether to use deferrable timers or not
-                 e.g. "echo 1 > /sys/kernel/mm/ksm/deferrable_timer"
-                 Default: 0 (means, we are not using deferrable timers. Users
-		 might want to set deferrable_timer option if they donot want
-		 ksm thread to wakeup CPU to carryout ksm activities thus
-		 gaining on battery while compromising slightly on memory
-		 that could have been saved.)
+                   e.g. "echo 1 > /sys/kernel/mm/ksm/deferrable_timer"
+                   Default: 0 (means, we are not using deferrable timers. Users
+		   might want to set deferrable_timer option if they donot want
+		   ksm thread to wakeup CPU to carryout ksm activities thus
+		   gaining on battery while compromising slightly on memory
+		   that could have been saved.)
 
 A high ratio of pages_sharing to pages_shared indicates good sharing, but
 a high ratio of pages_unshared to pages_sharing indicates wasted effort.
diff --git a/mm/ksm.c b/mm/ksm.c
index 2c5d206dfb6d..87ae13995d6d 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2202,10 +2202,11 @@ static ssize_t deferrable_timer_store(struct kobject *kobj,
 	int err;
 
 	err = kstrtoul(buf, 10, &enable);
-
-	if (enable == 0 || enable == 1)
-		use_deferrable_timer = enable;
-
+	if (err < 0)
+		return err;
+	if (enable >= 1)
+		return -EINVAL;
+	use_deferrable_timer = enable;
 	return count;
 }
 KSM_ATTR(deferrable_timer);