memcg: helper function for relcaim from shmem.
A new call, mem_cgroup_shrink_usage() is added for shmem handling and
relacing non-standard usage of mem_cgroup_charge/uncharge.
Now, shmem calls mem_cgroup_charge() just for reclaim some pages from
mem_cgroup. In general, shmem is used by some process group and not for
global resource (like file caches). So, it's reasonable to reclaim pages
from mem_cgroup where shmem is mainly used.
[hugh@veritas.com: shmem_getpage release page sooner]
[hugh@veritas.com: mem_cgroup_shrink_usage css_put]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a617061..f46b861 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -781,6 +781,32 @@
}
/*
+ * A call to try to shrink memory usage under specified resource controller.
+ * This is typically used for page reclaiming for shmem for reducing side
+ * effect of page allocation from shmem, which is used by some mem_cgroup.
+ */
+int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
+{
+ struct mem_cgroup *mem;
+ int progress = 0;
+ int retry = MEM_CGROUP_RECLAIM_RETRIES;
+
+ rcu_read_lock();
+ mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+ css_get(&mem->css);
+ rcu_read_unlock();
+
+ do {
+ progress = try_to_free_mem_cgroup_pages(mem, gfp_mask);
+ } while (!progress && --retry);
+
+ css_put(&mem->css);
+ if (!retry)
+ return -ENOMEM;
+ return 0;
+}
+
+/*
* This routine traverse page_cgroup in given list and drop them all.
* *And* this routine doesn't reclaim page itself, just removes page_cgroup.
*/