From: Sha Zhengju <handai.szj@xxxxxxxxxx>
Index current_threshold may point to threshold that just equal to
usage after last call of __mem_cgroup_threshold. But after registering
or unregistering 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@xxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
---
mm/memcontrol.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 22d94f5..34737b7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -183,7 +183,7 @@ struct mem_cgroup_threshold {
/* 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;
@@ -4193,7 +4193,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
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().
*/
@@ -4319,14 +4319,15 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
/* 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 */
@@ -4398,7 +4399,7 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
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
--
1.7.4.1
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