[PATCH] mm: fix NUMA statistics updates

[Janne Huttunen <janne.huttunen@nokia.com>]

Scan through the whole array to see if an update is needed. While we're
at it, use sizeof() to be safe against any possible type changes in the
future.

Fixes: 1d90ca897cb0 ("mm: update NUMA counter threshold size")
Signed-off-by: Janne Huttunen <janne.huttunen@nokia.com>
---
Compile tested only! I don't know what error (if any) only scanning
half of the array causes, so I cannot verify that this patch actually
fixes it.

 mm/vmstat.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 7878da7..eca984d 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1827,12 +1827,13 @@ static bool need_update(int cpu)
 
 		/*
 		 * The fast way of checking if there are any vmstat diffs.
-		 * This works because the diffs are byte sized items.
 		 */
-		if (memchr_inv(p->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS))
+		if (memchr_inv(p->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
+			       sizeof(p->vm_stat_diff[0])))
 			return true;
 #ifdef CONFIG_NUMA
-		if (memchr_inv(p->vm_numa_stat_diff, 0, NR_VM_NUMA_STAT_ITEMS))
+		if (memchr_inv(p->vm_numa_stat_diff, 0, NR_VM_NUMA_STAT_ITEMS *
+			       sizeof(p->vm_numa_stat_diff[0])))
 			return true;
 #endif
 	}
-- 
2.5.5