mm: memcontrol: uncharge pages on swapout
This series gets rid of the remaining page_cgroup flags, thus cutting the
memcg per-page overhead down to one pointer.
This patch (of 4):
mem_cgroup_swapout() is called with exclusive access to the page at the
end of the page's lifetime. Instead of clearing the PCG_MEMSW flag and
deferring the uncharge, just do it right away. This allows follow-up
patches to simplify the uncharge code.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.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 8c10d4c..266a440 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5777,6 +5777,7 @@
*/
void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
{
+ struct mem_cgroup *memcg;
struct page_cgroup *pc;
unsigned short oldid;
@@ -5793,13 +5794,22 @@
return;
VM_BUG_ON_PAGE(!(pc->flags & PCG_MEMSW), page);
+ memcg = pc->mem_cgroup;
- oldid = swap_cgroup_record(entry, mem_cgroup_id(pc->mem_cgroup));
+ oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
VM_BUG_ON_PAGE(oldid, page);
+ mem_cgroup_swap_statistics(memcg, true);
- pc->flags &= ~PCG_MEMSW;
- css_get(&pc->mem_cgroup->css);
- mem_cgroup_swap_statistics(pc->mem_cgroup, true);
+ pc->flags = 0;
+
+ if (!mem_cgroup_is_root(memcg))
+ page_counter_uncharge(&memcg->memory, 1);
+
+ /* XXX: caller holds IRQ-safe mapping->tree_lock */
+ VM_BUG_ON(!irqs_disabled());
+
+ mem_cgroup_charge_statistics(memcg, page, -1);
+ memcg_check_events(memcg, page);
}
/**