(2012/10/16 19:16), Glauber Costa wrote:

This patch introduces infrastructure for tracking kernel memory pages to
a given memcg. This will happen whenever the caller includes the flag
__GFP_KMEMCG flag, and the task belong to a memcg other than the root.

In memcontrol.h those functions are wrapped in inline acessors.  The
idea is to later on, patch those with static branches, so we don't incur
any overhead when no mem cgroups with limited kmem are being used.

Users of this functionality shall interact with the memcg core code
through the following functions:

memcg_kmem_newpage_charge: will return true if the group can handle the
                            allocation. At this point, struct page is not
                            yet allocated.

memcg_kmem_commit_charge: will either revert the charge, if struct page
                           allocation failed, or embed memcg information
                           into page_cgroup.

memcg_kmem_uncharge_page: called at free time, will revert the charge.

[ v2: improved comments and standardized function names ]
[ v3: handle no longer opaque, functions not exported,
   even more comments ]
[ v4: reworked Used bit handling and surroundings for more clarity ]
[ v5: simplified code for kmemcg compiled out and core functions in
   memcontrol.c, moved kmem code to the middle to avoid forward decls ]

Signed-off-by: Glauber Costa <redacted>
Acked-by: Michal Hocko <redacted>
CC: Christoph Lameter <redacted>
CC: Pekka Enberg <redacted>
CC: Kamezawa Hiroyuki <redacted>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Tejun Heo <tj@kernel.org>

Acked-by: KAMEZAWA Hiroyuki <redacted>



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