From 7bdd143c37e591c254d0991ac398a53f3f9ef1af Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 10 Dec 2014 15:43:54 -0800 Subject: [PATCH] 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 Cc: Hugh Dickins Acked-by: Michal Hocko Acked-by: Vladimir Davydov Reviewed-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8c10d4ca9c3f..266a440c89f9 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); } /**