On Wed, Dec 07, 2011 at 06:30:46PM +0800, Bob Liu wrote:
> uncharge will happen only when !page_mapped(page) no matter MEM_CGROUP_CHARGE_TYPE_DROP
> or MEM_CGROUP_CHARGE_TYPE_SWAPOUT when called from mem_cgroup_uncharge_swapcache().
> i think it's no difference, so drop it.
>
> Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
> ---
> mm/memcontrol.c | 5 -----
> 1 files changed, 0 insertions(+), 5 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6aff93c..02a2988 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -339,7 +339,6 @@ enum charge_type {
> MEM_CGROUP_CHARGE_TYPE_SHMEM, /* used by page migration of shmem */
> MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */
> MEM_CGROUP_CHARGE_TYPE_SWAPOUT, /* for accounting swapcache */
> - MEM_CGROUP_CHARGE_TYPE_DROP, /* a page was unused swap cache */
> NR_CHARGE_TYPE,
> };
>
> @@ -3000,7 +2999,6 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
>
> switch (ctype) {
> case MEM_CGROUP_CHARGE_TYPE_MAPPED:
> - case MEM_CGROUP_CHARGE_TYPE_DROP:
> /* See mem_cgroup_prepare_migration() */
> if (page_mapped(page) || PageCgroupMigration(pc))
> goto unlock_out;
> @@ -3121,9 +3119,6 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
> struct mem_cgroup *memcg;
> int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
>
> - if (!swapout) /* this was a swap cache but the swap is unused ! */
> - ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
> -
Pages are in swap cache for swapping in as well as for swapping out.
When a page is removed from swap cache and memory, the accounting
needs to know about the direction. See the other checks against
TYPE_SWAPOUT.
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