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>
This commit is contained in:
Johannes Weiner 2014-12-10 15:43:54 -08:00 committed by Linus Torvalds
parent b9982f8d27
commit 7bdd143c37
1 changed files with 14 additions and 4 deletions

View File

@ -5777,6 +5777,7 @@ static void __init enable_swap_cgroup(void)
*/
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 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
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);
}
/**