mm: memcontrol: uncharge pages on swapout (7bdd143c) · Commits · 戴 / test

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>

mm/memcontrol.c

+14 −4

Original line number	Diff line number	Diff line
		@@ -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 = 0;

		pc->flags &= ~PCG_MEMSW;
		css_get(&pc->mem_cgroup->css);
		mem_cgroup_swap_statistics(pc->mem_cgroup, true);
		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);
		}

		/**

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