On 12/08/2011 11:21 PM, KAMEZAWA Hiroyuki wrote:
On Mon,  5 Dec 2011 19:34:55 -0200
Glauber Costa<glom...@parallels.com>  wrote:

This patch lays down the foundation for the kernel memory component
of the Memory Controller.

As of today, I am only laying down the following files:

  * memory.independent_kmem_limit
  * memory.kmem.limit_in_bytes (currently ignored)
  * memory.kmem.usage_in_bytes (always zero)

Signed-off-by: Glauber Costa<glom...@parallels.com>
Reviewed-by: Kirill A. Shutemov<kir...@shutemov.name>
CC: Paul Menage<p...@paulmenage.org>
CC: Greg Thelen<gthe...@google.com>

As I wrote, please CC Johannes and  Michal Hocko for memcg related parts.

I forgot to add them to the patch itself, but they are in the CC list of the messages.

So they did get the mail.

A few questions.
==
+       val = !!val;
+
+       if (parent&&  parent->use_hierarchy&&
+          (val != parent->kmem_independent_accounting))
+               return -EINVAL;
==
Hm, why you check val != parent->kmem_independent_accounting ?

        if (parent&&  parent->use_hierarchy)
                return -EINVAL;
?

Because I thought that making sure that everybody in the chain is consistent, it will make things simpler for us. But I am happy to change that if you prefer.

BTW, you didn't check this cgroup has children or not.
I think

        if (this_cgroup->use_hierarchy&&
              !list_empty(this_cgroup->childlen))
                return -EINVAL;

Noted.

==
+       /*
+        * TODO: We need to handle the case in which we are doing
+        * independent kmem accounting as authorized by our parent,
+        * but then our parent changes its parameter.
+        */
+       cgroup_lock();
+       memcg->kmem_independent_accounting = val;
+       cgroup_unlock();

Do we need cgroup_lock() here ?

Well, I removed almost all instances of it from previous patches, so I guess this one can go as well.

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