On Fri, 14 Nov 2008 14:26:31 +0800
Li Zefan <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]>
Reviewed-by: Li Zefan <[EMAIL PROTECTED]>
Signed-off-by: KAMEZAWA Hiroyuki <[EMAIL PROTECTED]>

---
 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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