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mm: rmap: split out page_remove_file_rmap()

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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: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.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 2014-10-29 14:50:51 -07:00 committed by Linus Torvalds
parent d7365e783e
commit 8186eb6a79
1 changed files with 46 additions and 32 deletions
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78
mm/rmap.c
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@ -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);
__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 (PageTransHuge(page))
__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
__mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
-hpage_nr_pages(page));
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);
}
/*