From: Janne Huttunen janne.huttunen@nokia.com
[ Upstream commit 13c9aaf7fa01cc7600c61981609feadeef3354ec ]
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.
The bug here is that we wouldn't sync per-cpu counters into global ones if there was an update of numa_stats for higher cpus. Highly theoretical one though because it is much more probable that zone_stats are updated so we would refresh anyway. So I wouldn't bother to mark this for stable, yet something nice to fix.
[mhocko@suse.com: changelog enhancement] Link: http://lkml.kernel.org/r/1541601517-17282-1-git-send-email-janne.huttunen@no... Fixes: 1d90ca897cb0 ("mm: update NUMA counter threshold size") Signed-off-by: Janne Huttunen janne.huttunen@nokia.com Acked-by: Michal Hocko mhocko@suse.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/vmstat.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/vmstat.c b/mm/vmstat.c index ba91683264134..e2197b03da574 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1805,12 +1805,13 @@ 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 }