[PATCH 1/4] memcg: simplify page cache charging.

KAMEZAWA Hiroyuki
2011-12-14T07:50:37Z

From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

This patch is a clean up. No functional/logical changes.

Because of commit ef6a3c6311, FUSE uses replace_page_cache() instead
of add_to_page_cache(). Then, mem_cgroup_cache_charge() is not
called against FUSE's pages from splice.

So, Now, mem_cgroup_cache_charge() doesn't receive a page on LRU
unless it's not SwapCache.
For checking, WARN_ON_ONCE(PageLRU(page)) is added.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
mm/memcontrol.c | 31 +++++++++----------------------
1 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a9e92a6..947c62c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2710,6 +2710,7 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask)
{
struct mem_cgroup *memcg = NULL;
+ enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
int ret;

if (mem_cgroup_disabled())
@@ -2719,31 +2720,17 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,

if (unlikely(!mm))
mm = &init_mm;
+ if (!page_is_file_cache(page))
+ type = MEM_CGROUP_CHARGE_TYPE_SHMEM;

- if (page_is_file_cache(page)) {
- ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, &memcg, true);
- if (ret || !memcg)
- return ret;
-
- /*
- * FUSE reuses pages without going through the final
- * put that would remove them from the LRU list, make
- * sure that they get relinked properly.
- */
- __mem_cgroup_commit_charge_lrucare(page, memcg,
- MEM_CGROUP_CHARGE_TYPE_CACHE);
- return ret;
- }
- /* shmem */
- if (PageSwapCache(page)) {
+ if (!PageSwapCache(page)) {
+ ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);
+ WARN_ON_ONCE(PageLRU(page));
+ } else { /* page is swapcache/shmem */
ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &memcg);
if (!ret)
- __mem_cgroup_commit_charge_swapin(page, memcg,
- MEM_CGROUP_CHARGE_TYPE_SHMEM);
- } else
- ret = mem_cgroup_charge_common(page, mm, gfp_mask,
- MEM_CGROUP_CHARGE_TYPE_SHMEM);
-
+ __mem_cgroup_commit_charge_swapin(page, memcg, type);
+ }
return ret;
}

--
1.7.4.1