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Subject[PATCH] memcg: reduce size of per-cpu-stat to be appropriate size.(v2)
On Fri, 14 Nov 2008 14:26:31 +0800
Li Zefan <lizf@cn.fujitsu.com> wrote:
> free_out:
> for_each_node_state(node, N_POSSIBLE)
> free_mem_cgroup_per_zone_info(mem, node);
> if (cont->parent != NULL) <---- this check should be removed
> mem_cgroup_free(mem);
>
>
Exactrly. fixed one is here.
-Kame
==
As Jan Blunck <jblunck@suse.de> pointed out, allocating
per-cpu stat for memcg to the size of NR_CPUS is not good.

This patch changes mem_cgroup's cpustat allocation not based
on NR_CPUS but based on nr_cpu_ids.

Changelog:
- fixed lack of logic in error path.

From: Jan Blunck <jblunck@suse.de>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
mm/memcontrol.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
Index: mmotm-2.6.28-Nov10/mm/memcontrol.c
===================================================================
--- mmotm-2.6.28-Nov10.orig/mm/memcontrol.c
+++ mmotm-2.6.28-Nov10/mm/memcontrol.c
@@ -60,7 +60,7 @@ struct mem_cgroup_stat_cpu {
} ____cacheline_aligned_in_smp;

struct mem_cgroup_stat {
- struct mem_cgroup_stat_cpu cpustat[NR_CPUS];
+ struct mem_cgroup_stat_cpu cpustat[0];
};

/*
@@ -129,11 +129,10 @@ struct mem_cgroup {

int prev_priority; /* for recording reclaim priority */
/*
- * statistics.
+ * statistics. This must be placed at the end of memcg.
*/
struct mem_cgroup_stat stat;
};
-static struct mem_cgroup init_mem_cgroup;

enum charge_type {
MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
@@ -1292,23 +1291,30 @@ static void free_mem_cgroup_per_zone_inf
kfree(mem->info.nodeinfo[node]);
}

+static int mem_cgroup_size(void)
+{
+ int cpustat_size = nr_cpu_ids * sizeof(struct mem_cgroup_stat_cpu);
+ return sizeof(struct mem_cgroup) + cpustat_size;
+}
+
static struct mem_cgroup *mem_cgroup_alloc(void)
{
struct mem_cgroup *mem;
+ int size = mem_cgroup_size();

- if (sizeof(*mem) < PAGE_SIZE)
- mem = kmalloc(sizeof(*mem), GFP_KERNEL);
+ if (size < PAGE_SIZE)
+ mem = kmalloc(size, GFP_KERNEL);
else
- mem = vmalloc(sizeof(*mem));
+ mem = vmalloc(size);

if (mem)
- memset(mem, 0, sizeof(*mem));
+ memset(mem, 0, size);
return mem;
}

static void mem_cgroup_free(struct mem_cgroup *mem)
{
- if (sizeof(*mem) < PAGE_SIZE)
+ if (mem_cgroup_size() < PAGE_SIZE)
kfree(mem);
else
vfree(mem);
@@ -1321,13 +1327,9 @@ mem_cgroup_create(struct cgroup_subsys *
struct mem_cgroup *mem;
int node;

- if (unlikely((cont->parent) == NULL)) {
- mem = &init_mem_cgroup;
- } else {
- mem = mem_cgroup_alloc();
- if (!mem)
- return ERR_PTR(-ENOMEM);
- }
+ mem = mem_cgroup_alloc();
+ if (!mem)
+ return ERR_PTR(-ENOMEM);

res_counter_init(&mem->res);

@@ -1339,8 +1341,7 @@ mem_cgroup_create(struct cgroup_subsys *
free_out:
for_each_node_state(node, N_POSSIBLE)
free_mem_cgroup_per_zone_info(mem, node);
- if (cont->parent != NULL)
- mem_cgroup_free(mem);
+ mem_cgroup_free(mem);
return ERR_PTR(-ENOMEM);
}




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