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Commit 8186eb6a authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

mm: rmap: split out page_remove_file_rmap() 



page_remove_rmap() has too many branches on PageAnon() and is hard to
follow.  Move the file part into a separate function.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d7365e78

mm/rmap.c

+46 −32
Original line number Diff line number Diff line
@@ -1054,6 +1054,36 @@ void page_add_file_rmap(struct page *page) 
	mem_cgroup_end_page_stat(memcg, locked, flags);

}



static void page_remove_file_rmap(struct page *page)

{

	struct mem_cgroup *memcg;

	unsigned long flags;

	bool locked;



	memcg = mem_cgroup_begin_page_stat(page, &locked, &flags);



	/* page still mapped by someone else? */

	if (!atomic_add_negative(-1, &page->_mapcount))

		goto out;



	/* Hugepages are not counted in NR_FILE_MAPPED for now. */

	if (unlikely(PageHuge(page)))

		goto out;



	/*

	 * We use the irq-unsafe __{inc|mod}_zone_page_stat because

	 * these counters are not modified in interrupt context, and

	 * pte lock(a spinlock) is held, which implies preemption disabled.

	 */

	__dec_zone_page_state(page, NR_FILE_MAPPED);

	mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);



	if (unlikely(PageMlocked(page)))

		clear_page_mlock(page);

out:

	mem_cgroup_end_page_stat(memcg, locked, flags);

}



/**

 * page_remove_rmap - take down pte mapping from a page

 * @page: page to remove mapping from
@@ -1062,46 +1092,33 @@ void page_add_file_rmap(struct page *page) 
 */

void page_remove_rmap(struct page *page)

{

	struct mem_cgroup *uninitialized_var(memcg);

	bool anon = PageAnon(page);

	unsigned long flags;

	bool locked;



	/*

	 * The anon case has no mem_cgroup page_stat to update; but may

	 * uncharge_page() below, where the lock ordering can deadlock if

	 * we hold the lock against page_stat move: so avoid it on anon.

	 */

	if (!anon)

		memcg = mem_cgroup_begin_page_stat(page, &locked, &flags);

	if (!PageAnon(page)) {

		page_remove_file_rmap(page);

		return;

	}



	/* page still mapped by someone else? */

	if (!atomic_add_negative(-1, &page->_mapcount))

		goto out;

		return;



	/* Hugepages are not counted in NR_ANON_PAGES for now. */

	if (unlikely(PageHuge(page)))

		return;



	/*

	 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED

	 * and not charged by memcg for now.

	 *

	 * We use the irq-unsafe __{inc|mod}_zone_page_stat because

	 * these counters are not modified in interrupt context, and

	 * these counters are not modified in interrupt context, and

	 * pte lock(a spinlock) is held, which implies preemption disabled.

	 */

	if (unlikely(PageHuge(page)))

		goto out;

	if (anon) {

	if (PageTransHuge(page))

			__dec_zone_page_state(page,

					      NR_ANON_TRANSPARENT_HUGEPAGES);

		__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);



	__mod_zone_page_state(page_zone(page), NR_ANON_PAGES,

			      -hpage_nr_pages(page));

	} else {

		__dec_zone_page_state(page, NR_FILE_MAPPED);

		mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);

	}



	if (unlikely(PageMlocked(page)))

		clear_page_mlock(page);



	/*

	 * It would be tidy to reset the PageAnon mapping here,

	 * but that might overwrite a racing page_add_anon_rmap
@@ -1111,9 +1128,6 @@ void page_remove_rmap(struct page *page) 
	 * Leaving it set also helps swapoff to reinstate ptes

	 * faster for those pages still in swapcache.

	 */

out:

	if (!anon)

		mem_cgroup_end_page_stat(memcg, locked, flags);

}



/*