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

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

mm/memcontrol.c

+6 −5
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ 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;
@@ -4280,7 +4280,7 @@ 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().

	 */
@@ -4406,14 +4406,15 @@ 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 */
@@ -4482,7 +4483,7 @@ 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

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