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Commit b1b0deab authored by Chen Gang's avatar Chen Gang Committed by Linus Torvalds
Browse files

mm: memcontrol: let mem_cgroup_move_account() have effect only if MMU enabled 



When !MMU, it will report warning. The related warning with allmodconfig
under c6x:

    CC      mm/memcontrol.o
  mm/memcontrol.c:2802:12: warning: 'mem_cgroup_move_account' defined but not used [-Wunused-function]
   static int mem_cgroup_move_account(struct page *page,
              ^

Signed-off-by: default avatarChen Gang <gang.chen.5i5j@gmail.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6b637835

mm/memcontrol.c

+86 −86
Original line number Diff line number Diff line
@@ -2785,92 +2785,6 @@ void mem_cgroup_split_huge_fixup(struct page *head) 
}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



/**

 * mem_cgroup_move_account - move account of the page

 * @page: the page

 * @nr_pages: number of regular pages (>1 for huge pages)

 * @from: mem_cgroup which the page is moved from.

 * @to:	mem_cgroup which the page is moved to. @from != @to.

 *

 * The caller must confirm following.

 * - page is not on LRU (isolate_page() is useful.)

 * - compound_lock is held when nr_pages > 1

 *

 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"

 * from old cgroup.

 */

static int mem_cgroup_move_account(struct page *page,

				   unsigned int nr_pages,

				   struct mem_cgroup *from,

				   struct mem_cgroup *to)

{

	unsigned long flags;

	int ret;



	VM_BUG_ON(from == to);

	VM_BUG_ON_PAGE(PageLRU(page), page);

	/*

	 * The page is isolated from LRU. So, collapse function

	 * will not handle this page. But page splitting can happen.

	 * Do this check under compound_page_lock(). The caller should

	 * hold it.

	 */

	ret = -EBUSY;

	if (nr_pages > 1 && !PageTransHuge(page))

		goto out;



	/*

	 * Prevent mem_cgroup_migrate() from looking at page->mem_cgroup

	 * of its source page while we change it: page migration takes

	 * both pages off the LRU, but page cache replacement doesn't.

	 */

	if (!trylock_page(page))

		goto out;



	ret = -EINVAL;

	if (page->mem_cgroup != from)

		goto out_unlock;



	spin_lock_irqsave(&from->move_lock, flags);



	if (!PageAnon(page) && page_mapped(page)) {

		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],

			       nr_pages);

		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],

			       nr_pages);

	}



	if (PageWriteback(page)) {

		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK],

			       nr_pages);

		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK],

			       nr_pages);

	}



	/*

	 * It is safe to change page->mem_cgroup here because the page

	 * is referenced, charged, and isolated - we can't race with

	 * uncharging, charging, migration, or LRU putback.

	 */



	/* caller should have done css_get */

	page->mem_cgroup = to;

	spin_unlock_irqrestore(&from->move_lock, flags);



	ret = 0;



	local_irq_disable();

	mem_cgroup_charge_statistics(to, page, nr_pages);

	memcg_check_events(to, page);

	mem_cgroup_charge_statistics(from, page, -nr_pages);

	memcg_check_events(from, page);

	local_irq_enable();

out_unlock:

	unlock_page(page);

out:

	return ret;

}



#ifdef CONFIG_MEMCG_SWAP

static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,

					 bool charge)
@@ -4822,6 +4736,92 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma, 
	return page;

}



/**

 * mem_cgroup_move_account - move account of the page

 * @page: the page

 * @nr_pages: number of regular pages (>1 for huge pages)

 * @from: mem_cgroup which the page is moved from.

 * @to:	mem_cgroup which the page is moved to. @from != @to.

 *

 * The caller must confirm following.

 * - page is not on LRU (isolate_page() is useful.)

 * - compound_lock is held when nr_pages > 1

 *

 * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"

 * from old cgroup.

 */

static int mem_cgroup_move_account(struct page *page,

				   unsigned int nr_pages,

				   struct mem_cgroup *from,

				   struct mem_cgroup *to)

{

	unsigned long flags;

	int ret;



	VM_BUG_ON(from == to);

	VM_BUG_ON_PAGE(PageLRU(page), page);

	/*

	 * The page is isolated from LRU. So, collapse function

	 * will not handle this page. But page splitting can happen.

	 * Do this check under compound_page_lock(). The caller should

	 * hold it.

	 */

	ret = -EBUSY;

	if (nr_pages > 1 && !PageTransHuge(page))

		goto out;



	/*

	 * Prevent mem_cgroup_migrate() from looking at page->mem_cgroup

	 * of its source page while we change it: page migration takes

	 * both pages off the LRU, but page cache replacement doesn't.

	 */

	if (!trylock_page(page))

		goto out;



	ret = -EINVAL;

	if (page->mem_cgroup != from)

		goto out_unlock;



	spin_lock_irqsave(&from->move_lock, flags);



	if (!PageAnon(page) && page_mapped(page)) {

		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],

			       nr_pages);

		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],

			       nr_pages);

	}



	if (PageWriteback(page)) {

		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK],

			       nr_pages);

		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK],

			       nr_pages);

	}



	/*

	 * It is safe to change page->mem_cgroup here because the page

	 * is referenced, charged, and isolated - we can't race with

	 * uncharging, charging, migration, or LRU putback.

	 */



	/* caller should have done css_get */

	page->mem_cgroup = to;

	spin_unlock_irqrestore(&from->move_lock, flags);



	ret = 0;



	local_irq_disable();

	mem_cgroup_charge_statistics(to, page, nr_pages);

	memcg_check_events(to, page);

	mem_cgroup_charge_statistics(from, page, -nr_pages);

	memcg_check_events(from, page);

	local_irq_enable();

out_unlock:

	unlock_page(page);

out:

	return ret;

}



static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,

		unsigned long addr, pte_t ptent, union mc_target *target)

{