memcg: make threshold index in the right position
Index current_threshold may point to threshold that just equal to usage
after last call of __mem_cgroup_threshold. But after registering a new
event, it will change (pointing to threshold just below usage). So make
it consistent here.
For example:
now:
threshold array: 3 [5] 7 9 (usage = 6, [index] = 5)
next turn (after calling __mem_cgroup_threshold):
threshold array: 3 5 [7] 9 (usage = 7, [index] = 7)
after registering a new event (threshold = 10):
threshold array: 3 [5] 7 9 10 (usage = 7, [index] = 5)
Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 775b94b..a8abf91 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -181,7 +181,7 @@
/* For threshold */
struct mem_cgroup_threshold_ary {
- /* An array index points to threshold just below usage. */
+ /* An array index points to threshold just below or equal to usage. */
int current_threshold;
/* Size of entries[] */
unsigned int size;
@@ -4280,7 +4280,7 @@
usage = mem_cgroup_usage(memcg, swap);
/*
- * current_threshold points to threshold just below usage.
+ * current_threshold points to threshold just below or equal to usage.
* If it's not true, a threshold was crossed after last
* call of __mem_cgroup_threshold().
*/
@@ -4406,14 +4406,15 @@
/* Find current threshold */
new->current_threshold = -1;
for (i = 0; i < size; i++) {
- if (new->entries[i].threshold < usage) {
+ if (new->entries[i].threshold <= usage) {
/*
* new->current_threshold will not be used until
* rcu_assign_pointer(), so it's safe to increment
* it here.
*/
++new->current_threshold;
- }
+ } else
+ break;
}
/* Free old spare buffer and save old primary buffer as spare */
@@ -4482,7 +4483,7 @@
continue;
new->entries[j] = thresholds->primary->entries[i];
- if (new->entries[j].threshold < usage) {
+ if (new->entries[j].threshold <= usage) {
/*
* new->current_threshold will not be used
* until rcu_assign_pointer(), so it's safe to increment