Messages in this thread Patch in this message | | | Date | Wed, 3 Dec 2008 14:08:28 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | [PATCH 17/21] memcg_prev_priority_protect.patch |
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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Currently, mem_cgroup doesn't have own lock and almost its member doesn't need. (e.g. mem_cgroup->info is protected by zone lock, mem_cgroup->stat is per cpu variable)
However, there is one explict exception. mem_cgroup->prev_priorit need lock, but doesn't protect. Luckly, this is NOT bug because prev_priority isn't used for current reclaim code.
However, we plan to use prev_priority future again. Therefore, fixing is better.
In addision, we plan to reuse this lock for another member. Then "reclaim_param_lock" name is better than "prev_priority_lock".
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> mm/memcontrol.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)
Index: mmotm-2.6.28-Dec02/mm/memcontrol.c =================================================================== --- mmotm-2.6.28-Dec02.orig/mm/memcontrol.c +++ mmotm-2.6.28-Dec02/mm/memcontrol.c @@ -144,6 +144,11 @@ struct mem_cgroup { */ struct mem_cgroup_lru_info info; + /* + protect against reclaim related member. + */ + spinlock_t reclaim_param_lock; + int prev_priority; /* for recording reclaim priority */ /* @@ -400,18 +405,28 @@ int mem_cgroup_calc_mapped_ratio(struct */ int mem_cgroup_get_reclaim_priority(struct mem_cgroup *mem) { - return mem->prev_priority; + int prev_priority; + + spin_lock(&mem->reclaim_param_lock); + prev_priority = mem->prev_priority; + spin_unlock(&mem->reclaim_param_lock); + + return prev_priority; } void mem_cgroup_note_reclaim_priority(struct mem_cgroup *mem, int priority) { + spin_lock(&mem->reclaim_param_lock); if (priority < mem->prev_priority) mem->prev_priority = priority; + spin_unlock(&mem->reclaim_param_lock); } void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority) { + spin_lock(&mem->reclaim_param_lock); mem->prev_priority = priority; + spin_unlock(&mem->reclaim_param_lock); } int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone) @@ -2070,6 +2085,7 @@ mem_cgroup_create(struct cgroup_subsys * } mem_cgroup_set_inactive_ratio(mem); mem->last_scanned_child = NULL; + spin_lock_init(&mem->reclaim_param_lock); return &mem->css; free_out:
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