Commit 748dad36 authored by Sha Zhengju's avatar Sha Zhengju Committed by Linus Torvalds

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: default avatarSha Zhengju <handai.szj@taobao.com>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a0db00fc
...@@ -181,7 +181,7 @@ struct mem_cgroup_threshold { ...@@ -181,7 +181,7 @@ struct mem_cgroup_threshold {
/* For threshold */ /* For threshold */
struct mem_cgroup_threshold_ary { 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; int current_threshold;
/* Size of entries[] */ /* Size of entries[] */
unsigned int size; unsigned int size;
...@@ -4280,7 +4280,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) ...@@ -4280,7 +4280,7 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
usage = mem_cgroup_usage(memcg, 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 * If it's not true, a threshold was crossed after last
* call of __mem_cgroup_threshold(). * call of __mem_cgroup_threshold().
*/ */
...@@ -4406,14 +4406,15 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp, ...@@ -4406,14 +4406,15 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
/* Find current threshold */ /* Find current threshold */
new->current_threshold = -1; new->current_threshold = -1;
for (i = 0; i < size; i++) { 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 * new->current_threshold will not be used until
* rcu_assign_pointer(), so it's safe to increment * rcu_assign_pointer(), so it's safe to increment
* it here. * it here.
*/ */
++new->current_threshold; ++new->current_threshold;
} } else
break;
} }
/* Free old spare buffer and save old primary buffer as spare */ /* Free old spare buffer and save old primary buffer as spare */
...@@ -4482,7 +4483,7 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp, ...@@ -4482,7 +4483,7 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
continue; continue;
new->entries[j] = thresholds->primary->entries[i]; 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 * new->current_threshold will not be used
* until rcu_assign_pointer(), so it's safe to increment * until rcu_assign_pointer(), so it's safe to increment
......
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